\\n\\n
Dr. Pletser’s experience includes 30 years of working with the European Space Agency as a Senior Physicist/Engineer and coordinating their parabolic flight campaigns, and he is the Guinness World Record holder for the most number of aircraft flown (12) in parabolas, personally logging more than 7,300 parabolas.
\\n\\nSeeing the 5,000th book published makes us at the same time proud, happy, humble, and grateful. This is a great opportunity to stop and celebrate what we have done so far, but is also an opportunity to engage even more, grow, and succeed. It wouldn't be possible to get here without the synergy of team members’ hard work and authors and editors who devote time and their expertise into Open Access book publishing with us.
\\n\\nOver these years, we have gone from pioneering the scientific Open Access book publishing field to being the world’s largest Open Access book publisher. Nonetheless, our vision has remained the same: to meet the challenges of making relevant knowledge available to the worldwide community under the Open Access model.
\\n\\nWe are excited about the present, and we look forward to sharing many more successes in the future.
\\n\\nThank you all for being part of the journey. 5,000 times thank you!
\\n\\nNow with 5,000 titles available Open Access, which one will you read next?
\\n\\nRead, share and download for free: https://www.intechopen.com/books
\\n\\n\\n\\n
\\n"}]',published:!0,mainMedia:null},components:[{type:"htmlEditorComponent",content:'
Preparation of Space Experiments edited by international leading expert Dr. Vladimir Pletser, Director of Space Training Operations at Blue Abyss is the 5,000th Open Access book published by IntechOpen and our milestone publication!
\n\n"This book presents some of the current trends in space microgravity research. The eleven chapters introduce various facets of space research in physical sciences, human physiology and technology developed using the microgravity environment not only to improve our fundamental understanding in these domains but also to adapt this new knowledge for application on earth." says the editor. Listen what else Dr. Pletser has to say...
\n\n\n\nDr. Pletser’s experience includes 30 years of working with the European Space Agency as a Senior Physicist/Engineer and coordinating their parabolic flight campaigns, and he is the Guinness World Record holder for the most number of aircraft flown (12) in parabolas, personally logging more than 7,300 parabolas.
\n\nSeeing the 5,000th book published makes us at the same time proud, happy, humble, and grateful. This is a great opportunity to stop and celebrate what we have done so far, but is also an opportunity to engage even more, grow, and succeed. It wouldn't be possible to get here without the synergy of team members’ hard work and authors and editors who devote time and their expertise into Open Access book publishing with us.
\n\nOver these years, we have gone from pioneering the scientific Open Access book publishing field to being the world’s largest Open Access book publisher. Nonetheless, our vision has remained the same: to meet the challenges of making relevant knowledge available to the worldwide community under the Open Access model.
\n\nWe are excited about the present, and we look forward to sharing many more successes in the future.
\n\nThank you all for being part of the journey. 5,000 times thank you!
\n\nNow with 5,000 titles available Open Access, which one will you read next?
\n\nRead, share and download for free: https://www.intechopen.com/books
\n\n\n\n
\n'}],latestNews:[{slug:"stanford-university-identifies-top-2-scientists-over-1-000-are-intechopen-authors-and-editors-20210122",title:"Stanford University Identifies Top 2% Scientists, Over 1,000 are IntechOpen Authors and Editors"},{slug:"intechopen-authors-included-in-the-highly-cited-researchers-list-for-2020-20210121",title:"IntechOpen Authors Included in the Highly Cited Researchers List for 2020"},{slug:"intechopen-maintains-position-as-the-world-s-largest-oa-book-publisher-20201218",title:"IntechOpen Maintains Position as the World’s Largest OA Book Publisher"},{slug:"all-intechopen-books-available-on-perlego-20201215",title:"All IntechOpen Books Available on Perlego"},{slug:"oiv-awards-recognizes-intechopen-s-editors-20201127",title:"OIV Awards Recognizes IntechOpen's Editors"},{slug:"intechopen-joins-crossref-s-initiative-for-open-abstracts-i4oa-to-boost-the-discovery-of-research-20201005",title:"IntechOpen joins Crossref's Initiative for Open Abstracts (I4OA) to Boost the Discovery of Research"},{slug:"intechopen-hits-milestone-5-000-open-access-books-published-20200908",title:"IntechOpen hits milestone: 5,000 Open Access books published!"},{slug:"intechopen-books-hosted-on-the-mathworks-book-program-20200819",title:"IntechOpen Books Hosted on the MathWorks Book Program"}]},book:{item:{type:"book",id:"3111",leadTitle:null,fullTitle:"Hydraulic Conductivity",title:"Hydraulic Conductivity",subtitle:null,reviewType:"peer-reviewed",abstract:"This book is a research publication that covers original research on developments within the Hydraulic Conductivity field of study. The book is a collection of reviewed scholarly contributions written by different authors. Each scholarly contribution represents a chapter and each chapter is complete in itself but related to the major topics and objectives.",isbn:null,printIsbn:"978-953-51-1208-2",pdfIsbn:"978-953-51-6357-2",doi:"10.5772/3410",price:119,priceEur:129,priceUsd:155,slug:"hydraulic-conductivity",numberOfPages:220,isOpenForSubmission:!1,isInWos:1,hash:"9058b2c13f96f32e88d1040e331f03b0",bookSignature:"Vanderlei Rodrigues da Silva",publishedDate:"December 4th 2013",coverURL:"https://cdn.intechopen.com/books/images_new/3111.jpg",numberOfDownloads:11443,numberOfWosCitations:6,numberOfCrossrefCitations:4,numberOfDimensionsCitations:6,hasAltmetrics:0,numberOfTotalCitations:16,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"March 13th 2012",dateEndSecondStepPublish:"April 3rd 2012",dateEndThirdStepPublish:"September 1st 2012",dateEndFourthStepPublish:"October 1st 2012",dateEndFifthStepPublish:"January 1st 2013",currentStepOfPublishingProcess:5,indexedIn:"1,2,3,4,5,6,7",editedByType:"Edited by",kuFlag:!1,editors:[{id:"153109",title:"Dr.",name:"Vanderlei Rodrigues Da",middleName:null,surname:"Silva",slug:"vanderlei-rodrigues-da-silva",fullName:"Vanderlei Rodrigues Da Silva",profilePictureURL:"https://mts.intechopen.com/storage/users/153109/images/system/153109.jpg",biography:"Prof. Vanderlei Rodrigues da Silva graduated in Agronomy from the Federal University of Santa Maria (1996). He received his MSc degree in Agronomy from the Federal University of Santa Maria (1999) and Ph.D. in Agronomy from the Federal University of Santa Maria (2003). Prof. Vanderlei Rodrigues da Silva is currently assistant professor at the Federal University of Santa Maria, Tutor Group PET Agronomy, Frederick and coordinator of the Agronomy, UFSM-FW. He has experience in Agronomy with emphasis on Soil Physics, acting on the following topics: soil compaction, tillage, soil density, soil management and soil mechanical parameters.",institutionString:null,position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"0",totalChapterViews:"0",totalEditedBooks:"1",institution:{name:"Universidade Federal de Santa Maria",institutionURL:null,country:{name:"Brazil"}}}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"780",title:"Ecological Engineering",slug:"ecological-engineering"}],chapters:[{id:"45346",title:"Hydraulic Efficiency and Safety of Xylem Sap Flow in Relation to Water Stress in Woody Plants",doi:"10.5772/56656",slug:"hydraulic-efficiency-and-safety-of-xylem-sap-flow-in-relation-to-water-stress-in-woody-plants",totalDownloads:2322,totalCrossrefCites:1,totalDimensionsCites:1,signatures:"Katarzyna Marciszewska and Mirela Tulik",downloadPdfUrl:"/chapter/pdf-download/45346",previewPdfUrl:"/chapter/pdf-preview/45346",authors:[{id:"30291",title:"Dr.",name:"Mirela",surname:"Tulik",slug:"mirela-tulik",fullName:"Mirela Tulik"},{id:"35790",title:"Dr.",name:"Katarzyna",surname:"Marciszewska",slug:"katarzyna-marciszewska",fullName:"Katarzyna Marciszewska"}],corrections:null},{id:"45592",title:"Role of Hydraulic Conductivity Uncertainties in Modeling Water Flow through Forest Watersheds",doi:"10.5772/56900",slug:"role-of-hydraulic-conductivity-uncertainties-in-modeling-water-flow-through-forest-watersheds",totalDownloads:1706,totalCrossrefCites:2,totalDimensionsCites:2,signatures:"Marie-France Jutras and Paul A. Arp",downloadPdfUrl:"/chapter/pdf-download/45592",previewPdfUrl:"/chapter/pdf-preview/45592",authors:[{id:"38345",title:"Prof.",name:"Paul",surname:"Arp",slug:"paul-arp",fullName:"Paul Arp"},{id:"46711",title:"Ms.",name:"Marie-France",surname:"Jutras",slug:"marie-france-jutras",fullName:"Marie-France Jutras"}],corrections:null},{id:"45544",title:"Eveluation of the Quality of the Soil From Soil Physical-Hydrical Indicators",doi:"10.5772/56875",slug:"eveluation-of-the-quality-of-the-soil-from-soil-physical-hydrical-indicators",totalDownloads:1154,totalCrossrefCites:0,totalDimensionsCites:0,signatures:"Paulo Leonel Libardi and Flávia Carvalho Silva",downloadPdfUrl:"/chapter/pdf-download/45544",previewPdfUrl:"/chapter/pdf-preview/45544",authors:[{id:"29167",title:"Dr.",name:"Flavia",surname:"Silva",slug:"flavia-silva",fullName:"Flavia Silva"},{id:"169028",title:"Dr.",name:"Paulo",surname:"Libardi",slug:"paulo-libardi",fullName:"Paulo Libardi"}],corrections:null},{id:"45447",title:"Unsaturated Hydraulic Conductivity of Fractal-Textured Soils",doi:"10.5772/56716",slug:"unsaturated-hydraulic-conductivity-of-fractal-textured-soils",totalDownloads:1783,totalCrossrefCites:1,totalDimensionsCites:1,signatures:"Yongfu Xu",downloadPdfUrl:"/chapter/pdf-download/45447",previewPdfUrl:"/chapter/pdf-preview/45447",authors:[{id:"153990",title:"Dr",name:null,surname:"Xu",slug:"xu",fullName:"Xu"}],corrections:null},{id:"45474",title:"Calibration of a New Device to Measure Water Content of Rocks",doi:"10.5772/56699",slug:"calibration-of-a-new-device-to-measure-water-content-of-rocks",totalDownloads:1490,totalCrossrefCites:0,totalDimensionsCites:0,signatures:"Maria Clementina Caputo and Rita Masciale",downloadPdfUrl:"/chapter/pdf-download/45474",previewPdfUrl:"/chapter/pdf-preview/45474",authors:[{id:"28905",title:"Prof.",name:"Maria Clementina",surname:"Caputo",slug:"maria-clementina-caputo",fullName:"Maria Clementina Caputo"},{id:"154310",title:"Dr.",name:"Rita",surname:"Masciale",slug:"rita-masciale",fullName:"Rita Masciale"}],corrections:null},{id:"45375",title:"Data Assimilation Application to the Subsurface Flow and Solute Transport",doi:"10.5772/56705",slug:"data-assimilation-application-to-the-subsurface-flow-and-solute-transport",totalDownloads:1173,totalCrossrefCites:0,totalDimensionsCites:2,signatures:"Bill X. Hu and Juxiu Tong",downloadPdfUrl:"/chapter/pdf-download/45375",previewPdfUrl:"/chapter/pdf-preview/45375",authors:[{id:"154048",title:"Prof.",name:"Bill",surname:"Hu",slug:"bill-hu",fullName:"Bill Hu"}],corrections:null},{id:"45399",title:"Detection of Permeable Bodies: From Laboratory Measurements to Seismic Measurements",doi:"10.5772/56698",slug:"detection-of-permeable-bodies-from-laboratory-measurements-to-seismic-measurements",totalDownloads:1824,totalCrossrefCites:0,totalDimensionsCites:0,signatures:"Jean Luc Mari and Béatrice Yven",downloadPdfUrl:"/chapter/pdf-download/45399",previewPdfUrl:"/chapter/pdf-preview/45399",authors:[{id:"154090",title:"Prof.",name:"Jean Luc",surname:"Mari",slug:"jean-luc-mari",fullName:"Jean Luc Mari"}],corrections:null}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},relatedBooks:[{type:"book",id:"3569",title:"Biodegradation",subtitle:"Life of Science",isOpenForSubmission:!1,hash:"bb737eb528a53e5106c7e218d5f12ec6",slug:"biodegradation-life-of-science",bookSignature:"Rolando Chamy and Francisca Rosenkranz",coverURL:"https://cdn.intechopen.com/books/images_new/3569.jpg",editedByType:"Edited by",editors:[{id:"165784",title:"Dr.",name:"Rolando",surname:"Chamy",slug:"rolando-chamy",fullName:"Rolando Chamy"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2190",title:"Biomass Now",subtitle:"Sustainable Growth and Use",isOpenForSubmission:!1,hash:"f8a1a12b5516a184685e6421805ff25d",slug:"biomass-now-sustainable-growth-and-use",bookSignature:"Miodrag Darko Matovic",coverURL:"https://cdn.intechopen.com/books/images_new/2190.jpg",editedByType:"Edited by",editors:[{id:"27708",title:"Dr.",name:"Miodrag Darko",surname:"Matovic",slug:"miodrag-darko-matovic",fullName:"Miodrag Darko Matovic"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3138",title:"Biomass Now",subtitle:"Cultivation and Utilization",isOpenForSubmission:!1,hash:"14aa4b6c2eb974aad5a2839688220b04",slug:"biomass-now-cultivation-and-utilization",bookSignature:"Miodrag Darko Matovic",coverURL:"https://cdn.intechopen.com/books/images_new/3138.jpg",editedByType:"Edited by",editors:[{id:"27708",title:"Dr.",name:"Miodrag Darko",surname:"Matovic",slug:"miodrag-darko-matovic",fullName:"Miodrag Darko Matovic"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2311",title:"Climate Change and Variability",subtitle:null,isOpenForSubmission:!1,hash:"2fb02ff1e1671367663032ec44d0cb85",slug:"climate-change-and-variability",bookSignature:"Suzanne Simard",coverURL:"https://cdn.intechopen.com/books/images_new/2311.jpg",editedByType:"Edited by",editors:[{id:"11062",title:"Prof.",name:"Suzanne",surname:"Simard",slug:"suzanne-simard",fullName:"Suzanne Simard"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1327",title:"Greenhouse Gases",subtitle:"Emission, Measurement and Management",isOpenForSubmission:!1,hash:"f810749db3ab5479aa80cd81c0509033",slug:"greenhouse-gases-emission-measurement-and-management",bookSignature:"Guoxiang Liu",coverURL:"https://cdn.intechopen.com/books/images_new/1327.jpg",editedByType:"Edited by",editors:[{id:"92642",title:"Dr.",name:"Guoxiang",surname:"Liu",slug:"guoxiang-liu",fullName:"Guoxiang Liu"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3540",title:"Biodegradation",subtitle:"Engineering and Technology",isOpenForSubmission:!1,hash:"0ee069d311f4d412f6bbf7180e3a8ea4",slug:"biodegradation-engineering-and-technology",bookSignature:"Rolando Chamy and Francisca Rosenkranz",coverURL:"https://cdn.intechopen.com/books/images_new/3540.jpg",editedByType:"Edited by",editors:[{id:"165784",title:"Dr.",name:"Rolando",surname:"Chamy",slug:"rolando-chamy",fullName:"Rolando Chamy"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2117",title:"Greenhouse Gases",subtitle:"Capturing, Utilization and Reduction",isOpenForSubmission:!1,hash:"8cf4593468574b6d25cf38dea36729b5",slug:"greenhouse-gases-capturing-utilization-and-reduction",bookSignature:"Guoxiang Liu",coverURL:"https://cdn.intechopen.com/books/images_new/2117.jpg",editedByType:"Edited by",editors:[{id:"92642",title:"Dr.",name:"Guoxiang",surname:"Liu",slug:"guoxiang-liu",fullName:"Guoxiang Liu"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3570",title:"Biodegradation of Hazardous and Special Products",subtitle:null,isOpenForSubmission:!1,hash:"29ce0f4a059cb02b060a2b4082ca81e0",slug:"biodegradation-of-hazardous-and-special-products",bookSignature:"Rolando Chamy and Francisca Rosenkranz",coverURL:"https://cdn.intechopen.com/books/images_new/3570.jpg",editedByType:"Edited by",editors:[{id:"165784",title:"Dr.",name:"Rolando",surname:"Chamy",slug:"rolando-chamy",fullName:"Rolando Chamy"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"449",title:"Environmental Impact of Biofuels",subtitle:null,isOpenForSubmission:!1,hash:"faa4e85fdce130eae4d51d73d23c4816",slug:"environmental-impact-of-biofuels",bookSignature:"Marco Aurélio dos Santos Bernardes",coverURL:"https://cdn.intechopen.com/books/images_new/449.jpg",editedByType:"Edited by",editors:[{id:"6625",title:"Dr.",name:"Marco Aurelio",surname:"Dos Santos Bernardes",slug:"marco-aurelio-dos-santos-bernardes",fullName:"Marco Aurelio Dos Santos Bernardes"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"2151",title:"Novel Approaches and Their Applications in Risk Assessment",subtitle:null,isOpenForSubmission:!1,hash:"b37b8b1a2ebbcf1d218f6d570c65f247",slug:"novel-approaches-and-their-applications-in-risk-assessment",bookSignature:"Yuzhou Luo",coverURL:"https://cdn.intechopen.com/books/images_new/2151.jpg",editedByType:"Edited by",editors:[{id:"117189",title:"Dr.",name:"Yuzhou",surname:"Luo",slug:"yuzhou-luo",fullName:"Yuzhou Luo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],ofsBooks:[]},correction:{item:{id:"65669",slug:"corrigendum-to-aedes-what-do-we-know-about-them-and-what-can-they-transmit",title:"Corrigendum to: Aedes: What Do We Know about Them and What Can They Transmit?",doi:null,correctionPDFUrl:"https://cdn.intechopen.com/pdfs/65669.pdf",downloadPdfUrl:"/chapter/pdf-download/65669",previewPdfUrl:"/chapter/pdf-preview/65669",totalDownloads:null,totalCrossrefCites:null,bibtexUrl:"/chapter/bibtex/65669",risUrl:"/chapter/ris/65669",chapter:{id:"63773",slug:"aedes-what-do-we-know-about-them-and-what-can-they-transmit-",signatures:"Biswadeep Das, Sayam Ghosal and Swabhiman Mohanty",dateSubmitted:"May 16th 2018",dateReviewed:"September 7th 2018",datePrePublished:"November 5th 2018",datePublished:null,book:{id:"8122",title:"Vectors and Vector-Borne Zoonotic Diseases",subtitle:null,fullTitle:"Vectors and Vector-Borne Zoonotic Diseases",slug:"vectors-and-vector-borne-zoonotic-diseases",publishedDate:"February 20th 2019",bookSignature:"Sara Savić",coverURL:"https://cdn.intechopen.com/books/images_new/8122.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"92185",title:"Dr.",name:"Sara",middleName:null,surname:"Savic",slug:"sara-savic",fullName:"Sara Savic"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:null}},chapter:{id:"63773",slug:"aedes-what-do-we-know-about-them-and-what-can-they-transmit-",signatures:"Biswadeep Das, Sayam Ghosal and Swabhiman Mohanty",dateSubmitted:"May 16th 2018",dateReviewed:"September 7th 2018",datePrePublished:"November 5th 2018",datePublished:null,book:{id:"8122",title:"Vectors and Vector-Borne Zoonotic Diseases",subtitle:null,fullTitle:"Vectors and Vector-Borne Zoonotic Diseases",slug:"vectors-and-vector-borne-zoonotic-diseases",publishedDate:"February 20th 2019",bookSignature:"Sara Savić",coverURL:"https://cdn.intechopen.com/books/images_new/8122.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"92185",title:"Dr.",name:"Sara",middleName:null,surname:"Savic",slug:"sara-savic",fullName:"Sara Savic"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:null},book:{id:"8122",title:"Vectors and Vector-Borne Zoonotic Diseases",subtitle:null,fullTitle:"Vectors and Vector-Borne Zoonotic Diseases",slug:"vectors-and-vector-borne-zoonotic-diseases",publishedDate:"February 20th 2019",bookSignature:"Sara Savić",coverURL:"https://cdn.intechopen.com/books/images_new/8122.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"92185",title:"Dr.",name:"Sara",middleName:null,surname:"Savic",slug:"sara-savic",fullName:"Sara Savic"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}}},ofsBook:{item:{type:"book",id:"8935",leadTitle:null,title:"Mineral Deficiencies - Electrolyte Disturbances, Genes, Diet and Disease Interface",subtitle:null,reviewType:"peer-reviewed",abstract:"
\r\n\tMinerals are one of the four groups of essential nutrients, beside vitamins, essential fatty acids, and essential amino acids.
\r\n\tThis book intends to cover major mineral deficiency problems such as calcium, iron, magnesium, sodium, potassium and zinc. These minerals have very important task either on intracellular or extracellular level as well as regulatory functions in maintaining body homeostasis.
\r\n\t
\r\n\tBoth macrominerals and trace minerals (microminerals) are equally important, but trace minerals are needed in smaller amounts than major minerals. The measurements of these minerals quite differ. Mineral levels depend on their uptake, metabolism, consumption, absorption, lifestyle, medical drug therapies, physical activities etc.
\r\n\tAs a self-contained collection of scholarly papers, the book will target an audience of practicing researchers, academics, PhD students and other scientists. Since it will be published as an Open Access publication, it will allow unrestricted online access to chapters with no reading or subscription fees.
",isbn:"978-1-83881-085-6",printIsbn:"978-1-83881-081-8",pdfIsbn:"978-1-83881-086-3",doi:null,price:0,priceEur:0,priceUsd:0,slug:null,numberOfPages:0,isOpenForSubmission:!1,hash:"8bc7bd085801296d26c5ea58a7154de3",bookSignature:"Dr. Gyula Mozsik and Dr. Gonzalo Díaz-Soto",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/8935.jpg",keywords:"Calcium, Iron, Magnesium, Potassium, Sodium, Zinc, Diagnostic tools, Treatments, Food Fortification, Malnutrition, Metabolic Disorders, Lifestyle",numberOfDownloads:736,numberOfWosCitations:0,numberOfCrossrefCitations:0,numberOfDimensionsCitations:0,numberOfTotalCitations:0,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"May 26th 2020",dateEndSecondStepPublish:"June 16th 2020",dateEndThirdStepPublish:"August 15th 2020",dateEndFourthStepPublish:"November 3rd 2020",dateEndFifthStepPublish:"January 2nd 2021",remainingDaysToSecondStep:"8 months",secondStepPassed:!0,currentStepOfPublishingProcess:5,editedByType:null,kuFlag:!1,biosketch:"Professor Emeritus of Medicine at Univesity of Pecs, Hungary, and recipient of Andre Roberts award from the International Union of Pharmacology in 2014. He published 360 peer-reviewed papers, 196 book chapters, 692 abstracts, 19 monographs, and edited 32 books.",coeditorOneBiosketch:null,coeditorTwoBiosketch:null,coeditorThreeBiosketch:null,coeditorFourBiosketch:null,coeditorFiveBiosketch:null,editors:[{id:"58390",title:"Dr.",name:"Gyula",middleName:null,surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik",profilePictureURL:"https://mts.intechopen.com/storage/users/58390/images/system/58390.jpg",biography:"Gyula Mózsik, MD,PhD, ScD(med) is a professor emeritus of medicine at First Department of Medicine, Univesity of Pécs, Hungary. He was head of the Department from 1993 to 2003. His specializations are medicine, gastroenterology, clinical pharmacology, clinical nutrition. His research fields are biochemical and molecular pharmacological studies in gastrointestinal tract, clinical pharmacological and clinical nutritional studies, clinical genetic studies, and innovative pharmacological and nutritional (dietetical) research in new drug production and food production. He published around 360 peer-reviewed papers, 196 book chapters, 692 abstracts, 19 monographs, 32 edited books. He organized 38 national and international (in Croatia ,France, Romania, Italy, U.S.A., Japan) congresses /Symposia. He received the Andre Robert’s award from the International Union of Pharmacology, Gastrointestinal Section (2014). Fourteen of his students were appointed as full professors in Cuba, Egypt and Hungary.",institutionString:"University of Pécs",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"22",totalChapterViews:"0",totalEditedBooks:"9",institution:{name:"University of Pecs",institutionURL:null,country:{name:"Hungary"}}}],coeditorOne:{id:"92633",title:"Dr.",name:"Gonzalo",middleName:null,surname:"Díaz-Soto",slug:"gonzalo-diaz-soto",fullName:"Gonzalo Díaz-Soto",profilePictureURL:"https://mts.intechopen.com/storage/users/92633/images/3485_n.jpg",biography:"Dr. Gonzalo Díaz-Soto is Associate Professor of Endocrinology and Nutrition in Medical School of Valladolid University and researcher at the Endocrinology and Nutrition Institute (IEN) at the same University. He received his MD and Master in Bioscience in experimental Endocrinology and Calcium Sensing Receptor from the Medical School of Valladolid. He finished his specialisation on Endocrinology and Nutrition Hospital Clinic of Barcelona. He currently works at the Clinical University Hospital of Valladolid in the Endocrinology, Diabetes and Nutrition Department.",institutionString:"University of Valladolid",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"1",totalChapterViews:"0",totalEditedBooks:"2",institution:{name:"Hospital Clínico Universitario de Valladolid",institutionURL:null,country:{name:"Spain"}}},coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"6",title:"Biochemistry, Genetics and Molecular Biology",slug:"biochemistry-genetics-and-molecular-biology"}],chapters:[{id:"72450",title:"Parathyroid Glands and Hyperparathyroidism: A General Overview",slug:"parathyroid-glands-and-hyperparathyroidism-a-general-overview",totalDownloads:108,totalCrossrefCites:0,authors:[null]},{id:"73735",title:"Mineral Deficiencies a Root Cause for Reduced Longevity in Mammals",slug:"mineral-deficiencies-a-root-cause-for-reduced-longevity-in-mammals",totalDownloads:83,totalCrossrefCites:0,authors:[null]},{id:"73026",title:"Calcium and Metabolic Bone Disorders",slug:"calcium-and-metabolic-bone-disorders",totalDownloads:114,totalCrossrefCites:0,authors:[null]},{id:"72852",title:"Severe Hypocalcemia after Total Parathyroidectomy Plus Autotransplantation for Secondary Hyperthyroidism-Risk Factors and a Clinical Algorithm",slug:"severe-hypocalcemia-after-total-parathyroidectomy-plus-autotransplantation-for-secondary-hyperthyroi",totalDownloads:83,totalCrossrefCites:0,authors:[null]},{id:"72573",title:"Familial Syndromes of Primary Hyperparathyroidism",slug:"familial-syndromes-of-primary-hyperparathyroidism",totalDownloads:85,totalCrossrefCites:0,authors:[null]},{id:"73976",title:"Nutrigenomics: An Interface of Gene-Diet-Disease Interaction",slug:"nutrigenomics-an-interface-of-gene-diet-disease-interaction",totalDownloads:222,totalCrossrefCites:0,authors:[null]},{id:"74772",title:"Organoleptic, Sensory and Biochemical Traits of Arabica Coffee and their Arabusta Hybrids",slug:"organoleptic-sensory-and-biochemical-traits-of-arabica-coffee-and-their-arabusta-hybrids",totalDownloads:41,totalCrossrefCites:0,authors:[null]}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"184402",firstName:"Romina",lastName:"Rovan",middleName:null,title:"Ms.",imageUrl:"https://mts.intechopen.com/storage/users/184402/images/4747_n.jpg",email:"romina.r@intechopen.com",biography:"As an Author Service Manager my responsibilities include monitoring and facilitating all publishing activities for authors and editors. From chapter submission and review, to approval and revision, copyediting and design, until final publication, I work closely with authors and editors to ensure a simple and easy publishing process. I maintain constant and effective communication with authors, editors and reviewers, which allows for a level of personal support that enables contributors to fully commit and concentrate on the chapters they are writing, editing, or reviewing. I assist authors in the preparation of their full chapter submissions and track important deadlines and ensure they are met. I help to coordinate internal processes such as linguistic review, and monitor the technical aspects of the process. As an ASM I am also involved in the acquisition of editors. Whether that be identifying an exceptional author and proposing an editorship collaboration, or contacting researchers who would like the opportunity to work with IntechOpen, I establish and help manage author and editor acquisition and contact."}},relatedBooks:[{type:"book",id:"3317",title:"Current Topics in Gastritis",subtitle:"2012",isOpenForSubmission:!1,hash:"f771281e35f030a6438b269e736f910d",slug:"current-topics-in-gastritis-2012",bookSignature:"Gyula Mozsik",coverURL:"https://cdn.intechopen.com/books/images_new/3317.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3860",title:"Capsaicin - Sensitive Neural Afferentation and the Gastrointestinal Tract",subtitle:"from Bench to Bedside",isOpenForSubmission:!1,hash:"62e71e4f81c52b92224c231016a34231",slug:"capsaicin-sensitive-neural-afferentation-and-the-gastrointestinal-tract-from-bench-to-bedside",bookSignature:"Gyula Mozsik, Omar M. E. Abdel- Salam and Koji Takeuchi",coverURL:"https://cdn.intechopen.com/books/images_new/3860.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"5881",title:"Gastric Cancer",subtitle:null,isOpenForSubmission:!1,hash:"228701f521d44d2fff6d81063740d974",slug:"gastric-cancer",bookSignature:"Gyula Mózsik and Oszkár Karádi",coverURL:"https://cdn.intechopen.com/books/images_new/5881.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6810",title:"Capsaicin and its Human Therapeutic Development",subtitle:null,isOpenForSubmission:!1,hash:"9b0d5832824ac89f96d0557555448206",slug:"capsaicin-and-its-human-therapeutic-development",bookSignature:"Gyula Mozsik",coverURL:"https://cdn.intechopen.com/books/images_new/6810.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7103",title:"Constipation",subtitle:null,isOpenForSubmission:!1,hash:"0f5c714417d2c8a2e536ff6f78302cea",slug:"constipation",bookSignature:"Gyula Mózsik",coverURL:"https://cdn.intechopen.com/books/images_new/7103.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4817",title:"Membrane-bound Atp-dependent Energy Systems and the Gastrointestinal Mucosal Damage and Protection",subtitle:null,isOpenForSubmission:!1,hash:"33b0ab37b6c96db36130daafb1cd9701",slug:"membrane-bound-atp-dependent-energy-systems-and-the-gastrointestinal-mucosal-damage-and-protection",bookSignature:"Gyula Mozsik and Imre Szabo",coverURL:"https://cdn.intechopen.com/books/images_new/4817.jpg",editedByType:"Authored by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"3",chapterContentType:"chapter",authoredCaption:"Authored by"}},{type:"book",id:"7943",title:"Nutrition in Health and Disease",subtitle:"Our Challenges Now and Forthcoming Time",isOpenForSubmission:!1,hash:"bf9135b4940c5e9bf0f7de103e543946",slug:"nutrition-in-health-and-disease-our-challenges-now-and-forthcoming-time",bookSignature:"Gyula Mózsik and Mária Figler",coverURL:"https://cdn.intechopen.com/books/images_new/7943.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6924",title:"Adenosine Triphosphate in Health and Disease",subtitle:null,isOpenForSubmission:!1,hash:"04106c232a3c68fec07ba7cf00d2522d",slug:"adenosine-triphosphate-in-health-and-disease",bookSignature:"Gyula Mozsik",coverURL:"https://cdn.intechopen.com/books/images_new/6924.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"5162",title:"The Gut Microbiome",subtitle:"Implications for Human Disease",isOpenForSubmission:!1,hash:"f21c4722be61a42e7e6ed30cb898b9ad",slug:"the-gut-microbiome-implications-for-human-disease",bookSignature:"Gyula Mozsik",coverURL:"https://cdn.intechopen.com/books/images_new/5162.jpg",editedByType:"Edited by",editors:[{id:"58390",title:"Dr.",name:"Gyula",surname:"Mozsik",slug:"gyula-mozsik",fullName:"Gyula Mozsik"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6694",title:"New Trends in Ion Exchange Studies",subtitle:null,isOpenForSubmission:!1,hash:"3de8c8b090fd8faa7c11ec5b387c486a",slug:"new-trends-in-ion-exchange-studies",bookSignature:"Selcan Karakuş",coverURL:"https://cdn.intechopen.com/books/images_new/6694.jpg",editedByType:"Edited by",editors:[{id:"206110",title:"Dr.",name:"Selcan",surname:"Karakuş",slug:"selcan-karakus",fullName:"Selcan Karakuş"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"49179",title:"New Approaches to Preparation of SnO2-Based Varistors — Chemical Synthesis, Dopants, and Microwave Sintering",doi:"10.5772/61206",slug:"new-approaches-to-preparation-of-sno2-based-varistors-chemical-synthesis-dopants-and-microwave-sinte",body:'Varistor is an electrical device based on semiconductor materials used for protection against voltage spikes in the electric network, against overvoltage in electronic circuits of low voltage and electrical power systems [1,2].
Due to the high energy absorption, the ceramic varistors become many helpful in protecting electrical circuits, and their electrical properties are highly dependent on their microstructure. The development of devices ever more technological and brings the need for electrical protection due to the sensitivity equipment. The use of varistors as voltage protectors in electronic equipment is very simple: the varistor is directly connected in parallel to the power line of equipment, and in case of an increase in the electrical current on energy network, the varistor rapidly increases the conductivity, allowing the current flow toward the ground. For electrical appliances operating with few voltages, the varistors ceramics are called low-voltage varistors [1–3].
The first varistor ceramics were developed in 1930. They were constituted from compact silicon carbide (SiC) partially sintered and were designed by the System Bell Labs to replace selenium rectifiers that were used in the protection of telephone systems [4]. Over time, the processing of varistors has undergone successive improvements, and in 1968, Matsuoka [3] developed varistors based on zinc oxide with manganese and cobalt as a dopant to improve the electrical properties. One of the disadvantages of using ZnO-based varistors are the large amount of dopant added to ceramic matrix for its electric modification and consequently to its high chemical instability that leads to degradation of the varistor. Castro et al. [5] reported that the trapping of electrons, ion migration and oxygen adsorption are included as ZnO varistor degradation mechanisms. The exposure of ZnO varistors to high temperatures and oxidizing atmospheres leads to excess interstitial ions
The SnO2-based varistors were introduced by Pianaro et al. [7] as an alternative to the ZnO varistors commercial, presenting nonlinear electrical characteristics similar to ZnO varistors. The SnO2-based system shows more advantages, for example, their simpler microstructure and no formation of secondary phases require a lower concentration of agents modifiers to promote the varistor characteristics and densification and higher chemical and thermal resistances. The use of M2+ ion as dopant improved significantly the densification of the varistor, the addition of M5+ ion promoted electrical conductivity, and the M3+ ion influenced on nonlinearity coefficient.
The electrical properties of varistor ceramics are governed by potential barriers located in the grain boundaries. Potential barriers were formed by the addition of dopants elements to generate defects on crystal network, which segregate to the grain boundary region by diffusion during sintering. The presence of these barriers promotes the large-capacity power absorption and its flow when subjected to electrical overvoltage [4,8].
In denominated “smart ceramics,” the ceramic varistor acts as variable resistors, with resistive behavior at low voltages and conductive behavior starting from a specific voltage value, known as the breakdown voltage (VR) or breakdown electric field (ER) [9,10].
These electrical responses featuring the varistor ceramics as main elements in the manufacture of devices for electrical protection equipment subjected to both low and medium voltages apply directly as of the electro-electronics components (telephony system, computers, medical devices, automotive electronics, industrial automation systems, alarms, transformers, etc.) and for the high voltages used as part of lightning protection devices installed in the terminals of the power substations [11].
The varistor characteristic associated to quality is the nonlinear coefficient (α). The higher their value, the greater the varistor efficiency. This coefficient can be obtained through empirical relationships current × voltage (Eq. 1) or current density versus electric field (Eq. 2) and expresses how much the material deviates from ohmic response when required, and it can be explained by a graphic representation (Figure 1) with distinct regions [12–15].
where C is a constant related to the microstructure.
Electric field (E) versus current density (J) curves of a varistor [16].
The pre rupture region is also named as linear region and has an ohmic behavior when the material is under operation normal tension. The varistor acts as a resistor in this case with a small amount of current (known as leakage current) passing through the material due to the action of the potential barrier formed at grain boundary and preventing the electronic conduction between the grains. The conductivity in this region is of thermionic emission type, i.e., the electrical conduction is strongly dependent of temperature, thus being possible to retrieve information about the resistivity of the material [8,16,17].
The rupture region showed nonlinear behavior, i.e., non-ohmic behavior between the applied voltage and the current that the material is submitted. The conductivity of the material increases with a small variation in the applied voltage, indicating the varistor efficiency that starts to act as a conductor from a specific breakdown electric field (ER). Recombination of electron-hole pair at grain boundary interfaces, thermionic emission, and electron tunneling are suggested as electric conduction mechanisms of this region [8,16].
In the post rupture region, the ohmic behavior between the current and the applied voltage is observed once again and is characterized by high current density. The electric conduction in this region is controlled by the impedance of the grains [2,8].
The VR value provides the varistor voltage application, and it is a function of a grain size of sintered material. If the composition is fixed, the microstructure becomes strongly dependent on the processing conditions [12,15].
The varistor efficiency determined by the breakdown region can be evaluated by the α nonlinear coefficient of the curve in Figure 1, which is used in Eq. 6, derived from Eq. 3, which allows the calculation of the value of α by the field data electric (E) and current density (J) [18,19]:
The electric field and the current density are obtained from the measurements of the electric current (I) generated when the sample is submitted to a potential difference (V), according to Eqs. 4 and 5 [18,19]:
d is the thickness of the sample and A is the electrode area deposited on the film surface. For α calculation, the interval of 1 and 10 mA/cm2 of current density was used, i.e., J1 = 1 and J2 = 10 [18,19]:
The potential barrier is the determining factor on the electrical properties of varistors. Several models have been proposed to better understand the potential barrier formed in the grain boundary region [20,21].
Gupta et al. [22] proposed the first potential barrier model for ZnO-based varistor of the Schottky-type with an intergranular layer acting as insulator between the grains. In this model, negative charge densities (formed by Zn vacancies) were trapped between the grain boundary being balanced by two depletion layers that are positively charged. Leite et al. [23] proposed the accumulation of oxygen species adsorbed as new origin of negative defects [22,23].
Based on the ZnO potential barriers model, Bueno et al. [14] suggested a modification for formation of potential barrier in SnO2 varistors systems, whereas the sides of the barrier are in contact since there is no precipitated phase in the grain boundary, as observed Figure 2. In this model, the oxygen adsorbed species in the grain boundary region generate the negative charges defects, counterbalanced by the positive defects in the depletion layer. Pianaro et al. [1] proposed a potential barrier model, which has a large presence of negative charges on the SnO2 surface generated by tin vacancies (
Potential barrier model to ZnO varistors proposed by Gutpa et al. [22] and Leite et al. [23] and to SnO2 varistors base proposed by Bueno et al. [14] and Pianaro et al. [1].
In this model, the electrons are emitted and pass through the potential barriers particularly due to the action of temperature distorting the energy band diagram, near the interface. This distortion modifies the potential barrier favoring the thermal emission. The equation that describes this behavior is [24,25]
where A* is the Richardson constant, φb is the potential barrier height, E represents the electric field, T is the ambient temperature in Kelvin, and β is a constant related to the width of the potential barrier in accordance with the following equation [25]:
where n is the grain number per unit length and ω is the width of the barrier.
The emission of the Poole–Frenkel type assumes the formation of coulombian centers in the grain–intergranular layer interface region. The relationship that describes this type of emission is on Equation 9, where the external electric field variations are more relevant than for issue of Schottky type [26]:
where c is a constant of the material, T is the room temperature, E is the electric field, k is the Boltzmann constant, and φb is the height of the potential barrier. The thermionic emission cannot explain the high nonlinear coefficients observed in varistors. In the post rupture zone with the presence of high electric fields, the possibility that distortion of the energy levels and, therefore, the possibility that electrons pass through the potential barrier by tunneling must be considered [27].
The processing by mixing oxides is widely used at the industrial scale for the production of varistor ceramics mainly due to its low cost, consisting basically of an initial powder mix and wet milling followed by drying, deagglomeration of powder, forming pellets/bulks, and sintering. The varistor synthesis with large amounts of chemical additives and/or impurities resulting from the process can lead to non-densifying sintering mechanisms. This mean that impurities may accumulate on the material surface and increase the mass flow on the surface or forming more unstable compounds that can evaporate and condense on the surface, favoring grain growth without decreasing pore size. The advancement in ceramic materials process technology aims to find low-cost methods and the viability of the process on an industrial scale. Among the processes available in the literature for the production of ceramics, techniques can be cited as coprecipitation, sol-gel, dehydration by rapid cooling (freeze drying), combustion method, and polymeric precursor method known as the Pechini method [28–31].
Schematic representation of reactions developed in the polymeric precursor method (Pechini method) [31].
The polymeric precursor method involves a complexation reaction of metal ions by an organic complexing agent as carboxylic acid. The metal ions are complexed into carboxylic sites forming a metal carboxylate, which is sequentially polymerized with ethylene glycol, as shown in Figure 3, citric acid is often used as the complexing agent. This process shows advantages such as low temperature of synthesis and high control of stoichiometry, and allows the obtention of powder with nanometric particles. The immobilization of metal ion in organic matrix reduces the segregation of the metal during the decomposition of the polymer at high temperatures, thus ensuring a homogeneous composition [31]. The ceramic powders are obtained by controlled calcination of the resin until total oxide formation.
Another method widely used for controlled synthesis of multifunctional ceramics is the sol-gel, that is used for the synthesis of a colloidal suspension where the dispersed phase is a solid and the dispersion medium is liquid, and is called sol. Therefore, there is the formation of a dual phase material: a solid body that is occupied by a solvent, i.e., moist gel. The initiator compounds, commonly called precursors, consist of a metal surrounded by many connections and typically are inorganic salts or organic compounds. The two precursors undergo two chemical reactions at sol preparation: hydrolysis and condensation, which resulted from the addition of an acid or base catalyst to form small solid particles or clusters in a liquid (aqueous solvent) [32,33]. The sol-gel method provides homogenous mixtures of cations on an atomic scale and also allows the preparation of ceramic powders with high surface area and films or gels fibers, which have high technological importance. The method has advantages over other conventional methods such as high purity, resin calcination at low temperatures, and synthesis of oxides with defined and controlled properties [32–34].
Also, the controlled precipitation method (CPM) can be used to prepare precursor powders. In this case, the solution containing the cation of interest is added to another solution containing a precipitating agent that can be a base or anion (ammonia, urea, and oxalic acid). In this way, the final product precipitate is separated by filtration, washed, dried, and calcined to obtain the oxide. The precipitation process has a complex mechanism, which is dependent on the degree of saturation of the ion to be used. The process starts by formation of cluster from chemical species in the solution, known as nucleation process. Reaching the ion solubility limits the growth stage of formed centers and finally the formation of precipitates [35].
To check the influence of the chemical synthesis route the electrical properties of the SnO2-based varistors, Mosquera et al. [36] carried out the synthesis of tin oxide by controlled precipitation and polymeric precursor (Pechini) methods that’s offering the strict control of the chemical purity and the particle size of the raw material. The system SnO2.Co3O4.Nb2O5.TiO.Al2O3, with 1 mol% Co3O4, 0.05 mol% Nb2O5, and 1 mol% TiO2 and variations of 0.05 (named SCNT05A), 0.1 (named SCNT1A), and 0.2 mol% (named SCNT2A) of Al2O3 were prepared. Following synthesis, the materials were submitted to heat treatment at 600°C/1 h (controlled precipitation method, CPM) and 600°C/2 h (Pechini method, PCH) to eliminate organic matter and obtain the full formation of the oxide. The use of dopants in both methods resulted in no change in the SnO2-crystal structure or formation of secondary phases due to have been added small amounts of dopants (Figure 4). The SEM micrographs indicated the influence of the addition of the aluminum grain growth control. The Pechini method showed smaller grains and more porous samples.
SEM for sintered samples at 1350°C, obtained by CPM and PCH (a) 0.05% Al2O3 and (b) 0.1% Al2O3. XRD for varistor system whit 0.2% Al2O3 synthesized by CPM and PCH [36].
The aluminum concentration also influenced on the electrical properties, as shown in Figure 5, mainly in the breakdown electric field variation that had been related to decreasing of grain size. The samples showed nonlinear coefficient (α) of similar values, but the sample prepared by Pechini method and with 0.2% Al2O3 had the highest value for α (21.7) and the breakdown electric field (due to the smaller grain size).
log J versus log E curves of samples synthesized by (a) CPM and (b) PCH, sintered at 1350°C [36].
Sintering is the processing step that aims to confer mechanical strength to ceramic or metal powders, shaped by pressing or deposited as films. The process occurs by coalescence of the particles in solid or liquid phase to form a more dense mass. The sintering is an irreversible process and results in decrease of the total free energy of the system. Mathematically, the equation related to total energy of the system is
where ΔG is the total free energy, ΔGs is the surface free energy, and ΔGi is the energy of each particular system [37].
For the decrease of free energy of the system, there is a force that induces microstructural changes, replacing the contact points between the particles by grain boundaries, closing the pores, densifying, and making the material a hard solid. In addition to the system power source, the sintering mechanisms are also a contributing factor induced by driving forces. Figure 6 shows the possible forces involved in the sintering process: surface free energy, applied external pressure, and chemical reaction [38].
The three main drivers for solid densification: surface free energy, applied pressure, and chemical reaction [38].
Diagram flow of vacancies on the surface. The atoms flow is opposite to the vacancy [38].
The surface energy is related to the surfaces curve and characterized by vacancies and gaps. The surfaces energy is the main force that sinters the material by mass flow through the region of higher concentration to a lower concentration region where vacancies and gaps, as shown in Figure 7.
The variation of free energy during sintering is represented by Eq. 11:
where the free energy variation depends on the variation on interfacial energy as a function of the surface area. The surface tension solid–solid (γS/S) is smaller than the surface tension between vapor-solid (γS/V), and the interfacial energy is higher when there are many vacancies in the material, so there is a mass transfer gradient that favors the formation of necks between the particles and the resulting in joint, reducing the solid–vapor area (pore) [37].
In polycrystalline materials, the mass transport ways that are responsible for sintering are diffusion via crystal lattice, surface diffusion, volume diffusion, plastic flow, and evaporation–condensation. Figure 8 shows all mass transport paths arrive at the point of contact between two particles [38].
Mass transport mechanism solid and viscous sintering [38].
In Figure 8, the first three mechanisms do not lead to an alignment of the mass centers of the particles and therefore are non-densifying mechanisms. Thus, the mechanisms that start on the volume of material to the neck that increase in the neck and decrease the distance between the particles are densifying mechanisms [39].
The sintering mechanisms occur by three successive or simultaneously stages divided into initial, intermediate, and final stages. In some cases, there is the zero stage, which corresponds to particle rearrangement stage for subsequent joining by spot contact called necks [40]. The initial stage consists of particles rounding, formation of necks with low grain growth, and significant reduction in surface area and porosity. This stage progresses until the point where the necks interfere with each other. This stage corresponds to the point where the dihedral angle of equilibrium is reached. For the system with the green density of ~60%, this corresponds to a linear shrinkage of 3% to 5% [36]. It is possible to develop a general equation of the sintering kinetics for the initial stage. The geometric model for the development of this mathematical relationship is illustrated in Figure 9:
Frenkel’s model for early-stage sintering viscous flow [41].
The two spheres of the Frenkel’s model use the concept of viscous flow of atoms that relates the vacancy diffusion coefficient Dv, the volume of the atom or vacancy Ω, and vacancy concentration gradient per unit area of the material (dCv/dx), as shown in the following equation [41]:
Thus, the transported mass volume as a function of time can be given by [41]
were
Assuming that the decrease in surface energy of the system is equivalent to the energy dissipated through the material flow, then it is possible to derive several equations relating the radius of the neck and ball as a function of sintering time [38,42]:
where m and n are the sintering mechanisms, H is a function that varies with parameters such as diffusion rate, surface tension, atom or vacancy size, and a is the radius of the sphere.
Many aspects can be studied from the kinetic equations, as densification rate, determination of sintering mechanisms, and activation energy. The equation developed by Coble allows to estimate the sintering mechanisms for the initial stage, based on the two spheres Frenkel’s model, as indicated in the Eq. 15 [43]:
where n = 1, 2, 3, or 4, indicating the predominant mechanism of viscous flow, surface diffusion, and diffusion via grain boundary diffusion and via crystal lattice, and Y is the linear shrinkage of the sample, Q is the activation energy, R is the gas constant real, T is the temperature, and t is time.
The intermediate stage initiates densifying mechanisms as volumetric diffusion by crystal lattice in which there is rapid grain growth, shrinkage pore and increased in the density of the material up to ~90% of the theoretical density. Whereas there is grain growth, the model for the initial stage does not fit this stage. The final stage is characterized by the elimination of residual pores with little or no densification, but grain growth is observed. For the determination of sintering mechanisms, intermediate and final stages are used in the model-based grain growth [44]:
where G is the average grain size, Eab is the activation energy for moving contour or grain growth, n is the sintering mechanism when valley 3 is spread via reticulum and 4 is broadcast via grain boundary, and k0 is a constant that depends on temperature and sintering mechanisms [41,43,44].
Most of the kinetic studies of SnO2-based ceramic are developed to oxide mixed synthesis compressed into pellets, where significant amounts of mass are used. However, the appearance of thick and thin films makes possible the integration of smaller electric devices, and thus new techniques for the synthesis and deposition of powders on conductive and insulating rigid substrates have been studied.
The sintering of films has been increasingly used for applications in sensors, fuel cells, or photo catalysis that requires porous films [45,46]. This application is based on the fact that sintering occurs on rigid substrates such as viscous flow, wherein the voltage-limiting densification of the material is the force of attraction between the substrate and the deposited material particles [47,48]. The model used for understanding the sintering of thin films is based on Scherer and Garino’s studies where the rate of densification of the film is delayed by the substrate, as in Eq. 17 [38,41]:
The sintering mechanisms remain the same; however, the densification rate is retarded by tension caused by the substrate, like as the system would be sintered followed viscous sintering mechanism, as with glass.
One of the ceramic materials that have been very exploited for its great technological and industrial interest is the SnO2. Its applications are widely focused on sensors, solar cells, and catalysts, i.e., requiring high porosity, since its sintering process is limited to nondensifying mechanisms such as surface diffusion at low temperatures and evaporation–condensation at high temperatures [49–51]. Accordingly, what has been done to induce densifying sintering mechanisms is to cause solid substitution reactions that decrease the free energy by the formation of substitutional defects and vacancies that facilitate material transport during sintering [52].
It is possible to increase the densification of SnO2 by the addition of small amounts of lower valence densifying agents that generate substitutional defects and oxygen vacancies, such as ZnO, CoO, and MnO2, that promote the mass diffusion by solid solution, according to Eqs. 18, 19, and 20 [52,53]:
Also, there is the densification by CuO, Fe2O3, and MnO doping that promotes liquid solution formation [51]. Another way to improve the densification of SnO2-based varistors is to use the microwave as a source of power in the sintering process. According to Hao et al. [53], while conventional sintering occurs as a consequence of surface energy reduction, microwave sintering not only reduces the surface energy but also creates vacancies in the neck [53]. As a consequence of the increase in vacancies in grain necks, the mass flow also enhances in this region, promoting densification. In the case of dielectric materials, the oscillation of the electric field is the only external factor that will cause the internal heating of the material. Thus, the response of the oscillating electric field to the dielectric is determined by ε = ε ′ + i ε ″, where ε ′ is a dielectric constant that depends on the medium, and ε″ is the dielectric loss factor; when the material exhibits high dielectric loss, i.e., a high value ε″, the microwave energy is absorbed and converted into heat within the material [54]. When a material has high dielectric loss, the microwave can be directly applied to it; however, a susceptor material must be used. The susceptor absorbs microwave radiation and heats up the first piece so that it reaches its critical temperature, which consists of 40% to 50% of the melting temperature of the material above which has high dielectric losses.
Sintering mechanisms at Coble initial stage were adjusted to SnO2-based ceramic inserts with 0.95 mol% of ZnO sintered in a microwave oven and compared with results obtained in a conventional oven. The results showed that samples were sintered in a microwave oven to reach 87% after 30 min of sintering at 1050°C and grain size, while in a conventional oven, the density is 67%. It can be seen in Figure 10 by which the sample (a) is in the initial stage of sintering grain size, while in (b) indicating the morphology of the grains is already in intermediate sintering mechanism.
SEM of sintered samples in (a) conventional oven and (b) microwave oven, at 1050°C/30 min (by authors).
The sample sintered in a conventional oven showed a linear shrinkage of 5% and had an activation energy of 325 kJ/mol with predominant mechanisms at this early stage: structural rearrangement of particles, diffusion via crystal lattice, and surface diffusion, while samples sintered in microwave oven showed an activation energy of 111 kJ/mol and mechanisms as broadcast via crystalline reticulum. Figure 11 shows that there was a change sintering mechanisms for conventional sintering since there is a rate change in linear shrinkage rate of the material, whereas for microwave sintering the heating rate was rapid and lower temperature which does not inhibit sintering mechanisms densifying.
Curves of Ln(Y) versus Ln(t) with temperature as a parameter for obtaining the coefficients of sintering at initial stage, for SnO2 samples (doped with 0.95 mol% of ZnO) sintered in (a) oven conventional and (b) microwave oven (by authors).
The direct relationship between the grain growth and the increasing density for the samples subjected to microwave and conventional heating are shown in Figure 12. With their respective error bars, it may be said that for about the same density of 88% of the samples, the mean grain size for the sintered sample in a microwave oven at 1050°C for 30 min is 1.2 μm, while that for the samples sintered in a conventional oven at 1300°C/30 min is 1.8 μm, and this difference increases even more because it enters the final sintering stage, which is when the grains grow more sharply, so the grain size is increased to about 3 μm. The reduced grain samples sintered in a microwave oven results in more grain boundaries to increase the mechanical strength and modifying the electrical properties of the material.
Evolution of grain size as a function of the calculated density of the samples sintered in a conventional oven and a microwave oven at a temperature of 800 °C to 1050 °C [by authors].
Lustosa et al. [55] conducted a study on thick films of SnO2-based nanoparticles and their electrical properties. The ceramic powder with composition 98.95 mol% SnO2 + 1 mol% ZnO + 0.05 mol% Nb2O5 was synthesized by Pechini method, calcined in a muffle furnace, submitted to milling in the Attritor mill and to the separation of particles by gravimetry. After separation for use of the smaller particles, one ethylic aliquot containing SnO2 powder was taken to an electrophoretic deposition system (Figure 13) for obtain the films. In sequence, the films were submitted to sintering in a microwave oven at 1000°C/40 min. In order to improve the varistor property, a Cr3+ ion deposition was carried out (also by electrophoresis) on films surface, and then the samples were submitted to different heat treatment for the diffusion of cations in grain boundary region. Figure 14 shows the sintered film, which had a low porosity, homogeneous thickness to the full extent of the film. The chromium addition is known to improve the properties of a varistor system by acting on defect formation at grain boundary region and increase the potential barrier parameter.
Electrophoretic system for deposition of SnO2-based particles (by authors).
SEM of the film deposited by electrophoresis and sintered at 1000 °C/40 min: (a) top vision; (b) and (c) different magnifications of cross-sectional vision [55].
After the heat treatment for Cr3+ diffusion, the films were taken to the electrical characterization. From the varistor responses, shown in Figure 15, it was observed that the heat treatment used after the chromium deposition influenced the improvement of the nonlinear coefficient of the samples. All films had lower rupture voltage less than 65 V and a low leakage current.
Graphs of current density versus electric field: (a) for films without Cr3+ and films thermally treated at 900 °C and (b) films thermally treated at 1000 °C after the Cr3+ deposition [55].
The addition of crystal lattice modifiers to SnO2 matrix is required because in the SnO2 sintering process, there is a predominance of mass transport mechanisms (evaporation and condensation), which leads to coalescence and grain growth, which hinder densification. Densification is a precondition to obtain the varistor properties since the phenomena involved in the formulation of non-ohmic properties occur in the grain boundary region. Thus, the studies are carried out to understand the doping effect on the sintering and densification, electrical conductivity, and non-ohmic properties of SnO2-varistor. The defects generated by modifying agents are of Frenkel type (generators of interstitial ion) and Schottky type (generators of vacancies) and are responsible for the formation and modification of the potential barrier in the grain boundaries [1,56,57].
The addition of bivalent metals such as CoO [58], ZnO [59], and CuO [60,61] is made to enhance the densification because these cations act as acceptors of electrons and replace the tin ions in crystal lattice, creating oxygen vacancy defects that promote mass diffusion in the network and promoting densification, according to Eq. 21 [58]:
The
The electrical conductivity of the varistor system can be improved with the addition of pentavalent ions as Sb2O5 [62], Nb2O5 [1], and V2O5 [63], which act as electron donors to the crystal lattice, resulting in electron concentration and tin vacancies, as demonstrated in Eq. 22 [1,62]:
Trivalent cations that act as acceptors of electrons are added to SnO2 crystal lattice, such as chromium [63–65], ytterbium [67], and scandium [68], which were used to improve the varistor properties of the system. The segregation of these ions in the grain boundary potential barrier increases the resistivity values and causes the improvement of nonlinear coefficient due to the higher adsorption of electron acceptor species on the grain boundary surface, increasing the barrier height potential and decreasing the conductivity, as demonstrated in Eq. 23 [57,58,67]:
There are many papers available in the literature [56–58,61–63,66–70], which studied the influence of doping agent into the tin oxide matrix ceramic. The possible microstructural, morphological, and varistor property changes that may occur with the addition of certain elements are searched.
Aguilar-Martínez et al. [69] investigated the effect of calcium (sample named SCa), barium (sample named SBa), and strontium (sample named Sr) additions on the microstructure and electrical properties of SnO2-Co3O4-Sb2O5 ceramic varistors.
By XRD analysis, it should be noted that the concentrations of dopants added (SbO, CaO, Ba, and SrO) were too small to be detected by the X-ray equipment. The microstructure of the samples was characterized by scanning electron microscopy. As shown Figure 16, it was found that the addition of strontium and calcium promotes densification and grain growth. The addition of BaO leads to a significant alteration of microstructure, changing the grain size and the morphology of grains from a nearly round shape to smaller and elongated grains. Barium addition causes increase of porosity, reduction of grain size, and changes in the grain morphology (from approximately equiaxed to elongated grains) [69].
SEM images of the as-sintered surfaces of SnO2-based varistors: (a) S, (b) SCa, (c) SSr, and (d) SBa [69].
Since electrical conduction in SnO2-based varistor ceramics is controlled by the grain-boundary barriers, the observed fact (the significant grain growth in a SnO2-system with SrO and CaO added) suggests that Sr and Ca materials are more suitable for low-voltage varistor preparation. The current–voltage curves of all prepared ceramic samples are nonlinear behavior. Figure 17 shows graphs of current density versus electric field for ceramics with and without additions sintered at 1350 °C [69].
J versus E characteristic plots for all samples [69].
Ceramics with calcium addition exhibit the lowest electric field at a fixed current density (10–3 A cm–2). The addition of strontium shows a similar effect on microstructure and current–voltage characteristics. However, the BaO addition showed that low-field conductivity is slightly lower with respect to the reference material, but the high-field part remains unchanged. This behavior may be attributed to the resulting microstructure. Despite the grain morphology and porosity, the samples S (only Co an Sb as dopants), SCa, and SBa showed nonlinear coefficients of 5.7, 5.0, and 4.9, respectively, higher than the value for sample SSr (nonlinear coefficient of 2.7) [69].
The addition of Er2O3(Co, Nb)-doped SnO2 was studied by Qi et al. [70] at different concentrations (0.1, 0.5, 1, and 2 mol%) and different temperatures of sintering (1250 °C, 1300 °C, and 1350 °C for 1 h).The XRD analysis carried out by the authors did not show evidence of the second phase formation into the SnO2-rutile crystalline phase. The SEM micrographs of the varistors prepared are in Figure 18, showing the decreases of grain size associated with the increase of Er2O3 concentration into ceramic matrix. Also, the decreases of grain size occur with lower temperature of sintering. With the addition of 2.0 mol% of Er2O3 modifier agent, the SnO2 grain size was reduced from 12.9 μm to 6.5 μm when the sample sintered at 1350°C for1 h, from 9.7 μm to 3.7 μm when sample was sintered at 1300°C for 1 h, and from 6.8 μm to 2.4 μm when samples were sintered at 1250°C for 1 h.
Microstructure variation of the SnO2-based varistor system sintered at 1350 °C, 1300 °C, and 1250 °C during 1 h with the composition (all in mol%): 100SnO2 + 0.75Co2O3 + 0.1Nb2O5 + xEr2O3: (from top to bottom) x = 0.0, x = 0.1, x = 0.5, x = 1.0, x = 2.0 [70].
Figure 19 shows the plots of applied electric field versus current density for different concentrations of Er2O3 sintered at 1350 °C, 1300 °C, and 1250 °C during 1 h. It was observed from Figure 19 that the threshold voltage of the SnO2-based varistors increased significantly from 305 V mm−1 to 1083 V mm−1 with increasing Er2O3 concentrations over the range of 0–2.0 mol% sintered at 1350°C during 1 h and from 1083 V mm−1 to 2270 V mm−1 with decreasing sintered temperatures from 1350°C to 1250°C during1 h. Only the samples sintered at 1300 °C have decrease on nonlinear coefficient with Er2O3 addition. There is no observed significant change on height of the potential barrier for samples sintered ate 1250°C and 1300 °C.
E versus J curves for the SnO2-based varistor system sintered at different temperatures during 1 h with the composition (all in mol%) 100SnO2 + 0.75Co2O3 + 0.1Nb2O5 + xEr2O3 (x ranging from 0.0 to 2.0) [70].
The study of SnO2-based varistor systems is recent, so a huge amount of published papers do not exist. Research involving the material is mostly related to the understanding of the influence of dopants on densification materials prepared by mixing oxide and the change in the parameters of the potential barrier formed at grain boundary region, which is directly related to the nonlinear coefficient and determines the quality of varistor ceramics. The bivalent metals (Ba2+, Ca2+, Co2+, Zn2+, and others) have proven action as a densifying agent since the defects generated by their addition to the ceramic matrix assist in mass diffusion. The addition of trivalent ions (Cr3+, Er3+, and others) causes the increase of nonlinearity coefficient due to the higher adsorption electron acceptor species on the surface of the grain boundary and thus causing a reduction in conductivity of the material. The new methodologies for the chemical synthesis of ceramic powder promote the homogeneous distribution of dopants into the ceramic matrix and reduce segregation and the formation of secondary phases, confirmed by XRD analysis, which are harmful factors on the electrical properties of the varistor and facilitate the integration of the material in today’s electronic devices electrical protection. The use of microwave oven is a new processing step aimed to reduce the time and temperature of sintering step and can be considered a promising procedure for the varistors production. The preparation of varistors as film emerges as a new possibility in order to facilitate integration of this material in electronic circuits.
The authors thank the LMA-IQ and the financial support by the Brazilian research funding agencies CNPq and FAPESP (CEPID/CDMF- 2013/07296-2and process n°.
This chapter discusses the need for a dynamic strategy in turbulent business environment. The chapter starts by giving definitions to key terms like strategy and turbulent business environment. Tools that have been traditionally used to cope with environmental uncertainty have been looked at and how they can be complemented to yield better strategies and improve performance in a turbulent business environment.
\nIn this chapter the methodology employed was the qualitative systematic review of literature on the various aspects of the topic addressed which include strategy, dynamic strategy, turbulent business environment and dynamic capabilities among others. Basic ideas on how to conduct such a systematic review were borrowed from prominent scholars in the area [1]. Both integrative and interpretative techniques were used to uncover new understanding in the area of strategy. Using this methodology, various studies on dynamic strategy and turbulent business environment were brought together from various primary qualitative studies conducted and some in depth study on the subject matter was done resulting in conclusions being drawn. Thus qualitative synthesis of literature review was used as a basis for the arguments discussed in this chapter.
\nStrategy can be described as a plan of action that is designed to achieve a particular goal. Thus strategy is concerned with the setting and achieving of objectives and the process also involves the allocation of resources, which requires some consistency and cohesiveness of actions and decisions [2]. From its conception as a discipline, soon after the second world war, strategy has been greatly associated with systematic and detailed planning which distinguished it from other forms of planning. However this conception has been greatly challenged in the past few years as the business environment has become more dynamic and turbulent. Some strategic tools to cope with uncertainty in a turbulent business environment have been rendered ineffective, hence the need to seriously consider the phenomenon of strategy in a turbulent business environment. Thus there has been great emphasis on the need to shift from regarding strategy as a detailed and systematic plan to considering them as mere guidelines for action in a dynamic business environment. However research has proven that strategy is an indispensable aspect even in a turbulent environment though there is need to move away from traditional approaches to strategy and embrace more reactive approaches centred on strategic agility and organisational flexibility.
\nTurbulence can be best described as ‘unpredictable uncertainty for strategic planning purposes’ [3]. Environmental uncertainty is believed to arise when managers are not ‘confident that they understand the major changes and events in their industries’ [4]. Such an environment has also been regarded by some scholars as ‘hypercompetitive’ and it was taken to refer to ‘an environment of fierce competition leading to unsustainable advantage or the decline in the sustainability of advantage’ [5]. Earlier work on turbulence can be traced back to the work on capitalism and creative destruction [6]. However a hypercompetitive environment is regarded as surpassing the earlier ‘creative destruction’ of the 1930s which was mainly as a result of technological innovation and revolution [5]. Environmental turbulence can be taken to have been necessitated by several aspects which include rapid product innovation, changes in customer tastes and preferences, increased rates of technology transfer, employee and talent mobility, new internet capabilities, rapid technological changes and globalisation. Earlier studies attributed such changes to aspects like the emergence of trading blocks, excess capacity, structural changes, environmental concerns, reduced protectionism and technological discontinuities among others [7]. Failure to anticipate and embrace changes brought by these forces has been greatly attributed to the changing fortunes of the former leading and largest companies like General Motors, IBM and Xerox [7].
\nThus, research has shown that a turbulent business environment defies the key assumptions of traditional strategic planning which are regarded as mostly applicable in identifiable and stable industry structures [5, 7, 8]. This therefore necessitated the re-evaluation of most strategic management tools and concepts. For instance, sustainable competitive advantage, which was regarded as a key component of a good strategy, was regarded as non-existent and instead organisational flexibility and dynamic capabilities were considered as sources of sustainable advantage [5, 8]. Furthermore, arguments around Porter’s Five Forces model and the Resource Based View (RBV) of the firm were challenged since they were taken to be based on a stable business environment. This was due to the difficulties associated with measuring and assessing buyer, supplier and rivalry power as industries’ boundaries become blurred and hard to define in turbulent environments. Under such conditions the major underlying assumptions of the RBV were also defied as factor markets were considered as moving towards constant disruption and perfection as a result of rivalry and innovation.
\nThus under hypercompetitive conditions, temporary rather than sustainable advantages have been identified as existing and new theories like ‘entrepreneurial action’ [9] were formulated to replace some traditional strategic models. Changes in the business environment can either be incremental (also termed evolutionary or continuous) or discontinuous (revolutionary). Under these types of change different strategic approaches are called for to enable firms to cope with the growing uncertainty.
\nVarious tools have been traditionally used by firms to cope with strategic planning in fast paced business environments. These tools include environmental scanning, scenario analysis, real options analysis and technology and product road mapping. These tools and techniques have been used to identify drivers of change in the external business environment of companies. These tools will be looked at below, but it should not go unmentioned that these tools have been criticised on the grounds that most drivers of change interact in ways that are novel and unforeseeable to be easily detected by these tools.
\nEnvironmental scanning has been regarded as a process of acquiring and using information about trends, events and relationships in an organisation’s external environment which assists management in planning the future course of action [10]. It is believed that environmental scanning is well defined, systematically planned and executed and that it is directed at systematic and comprehensive data. This process is also taken to rely on regular, casual and informal information sources from all stakeholders [11] and it involves both information searching and viewing [10]. Organisations carry out environmental scanning so that they understand the external forces at work and develop effective responses to improve or secure their position in the future. They also scan the environment in order to identify opportunities and threats, avoid surprises, gain competitive advantage and enhance their short and long term planning.
\nThe ability of an organisation to adapt to its external environment depends heavily on its knowledge and interpretation of external changes at work. The quality of the information gathered from the scanning process or of the environmental scanning process itself is determined by the cognitive abilities of management. Furthermore, the organisation’s ability to survive depends on its ability to align its internal activities with the external constituents. Thus the scanning process should provide good quality (anticipatory) information that enables it to respond to the future developments in the environment by creating innovative entrepreneurial behaviour [11].
\nResearch has shown a positive correlation between environmental scanning and improved organisational performance [10]. However scanning alone has been regarded as insufficient to assure performance, but it should be aligned with strategy and the information obtained must be effectively utilised in the strategic planning process. It has been recommended that scanning should enhance and increase discussion and communication about future oriented planning in organisations and should induce strategic and organisational learning.
\nScenario analysis is one technique used to measure operational risk in organisations. Operational risk is defined as ‘the risk of loss resulting from inadequate or failed internal processes, people or systems or from external events’ [12]. Scenario analysis is a quantitative tool used to assess the impact of extreme events based on hypothesis or historical scenarios. It can be identified as a stress testing tool that allows institutions to obtain useful results from examining scenarios that cover infrequent but selective risks that can have a great impact on institutional operations.
\nIn scenario analysis estimations are based on ‘what-if’ scenarios that are generated on the basis of catastrophic events that occurred in other organisations, external data, expert opinion or extremely imagined events [11]. It is meant to investigate whether an organisation would be able to undergo exceptional risk losses. Basically there are two groups of scenarios whose classification is determined by the event type they define. The first category makes use of historical events like the September 2011 terrorist attacks or a strike and management investigates the potential impact of these events on the organisation. The second group uses hypothetical scenarios like some plausible risk events that have not yet happened but have some probability to occur.
\nHowever great care must be taken in using scenario analysis since it is very subjective and depends heavily on the choice of the scenarios used. Thus the use of irrelevant scenarios or bad assumptions can result in irrelevant losses.
\nA real option is regarded as the ‘right but not the obligation to acquire, expand, contract, abandon or switch some or all of an economic asset on fixed terms on or before the time the opportunity ceases to be available’ [13]. As suggested in the definition, some examples of real options include:
Option to switch resources
Option to expand
Option to delay
Option to wait and see
Option for future growth
Real options use options theory to evaluate physical or real assets and they give certain reactive plasticity on decision makers like the options to divest, wait or invest in in the face of new information. Traditionally, real options have been used to analyse troubled firms and firms involved in research and development with considerable amounts managerial flexibility under significant amounts of uncertainty.
\nThe real options approach is highly regarded since it ponders upon numerous decision pathways in the face of high uncertainty. It also gives management room for flexibility in selecting the optimal strategies or options along the way when new information becomes available. This approach is credited for assuming a multidimensionality series of decisions that give management room to adapt in the face of changes in the business environment. This helps management to hedge themselves against negative risks. Thus management has room to make strategy adjustments in the case of future uncertainty. Furthermore, as information becomes available and uncertainty clears, management can choose the best strategies to implement.
\nThis is a technology forecasting tool that aims at improving the ‘strategic technology planning process by linking the acquisition of technology to strategic objectives and the associated business and market drivers, enabling soundly-based technology investment to be taken’ [14]. Technology and product road mapping is used by companies to determine the future technological evolutions and appropriate actions that would enable companies to compete and survive in such a future.
\nIt is believed that technology road mapping has gone through two generations and that a third generation stage is still at its infantry stage [14]. The first generation is believed to have emerged from the 1970s to the mid-1980s. This generation is believed to have been centred on methodologies aimed at forecasting technology more accurately and clearly. The second generation was centred on methodologies aimed at improving strategic technology planning decisions and it span from the mid-1980s to the end of 1990s. The third generation with methodologies aimed at producing integrated technology management activities is believed to have emerged from the end of the 1990s to date. However it is believed that very few companies have adopted the third generation due to lack of supporting software that enable them to integrate it into their business processes.
\nThe above tools have been commonly used by businesses to enhance decision making at business and corporate level strategies. Since most of the techniques are future oriented, the terms ‘strategic foresight’ and ‘corporate foresight’ have been used to encompass these practices [4]. Strategic foresight is defined as a ‘future-intelligence gathering and medium to long-term vision-building process that aids present day decisions and mobilises joint actions in a systematic and participatory way’ [4].
\nIt is also defined as a set of technologies, tools, methods and actions that are used to provide an accurate description of both the present-day and future business environment of an entity [15]. It is considered as combining both expert analysis and technology to determine the most influential factors in the business environment that will have considerable effect on business development. Strategic foresight is also considered to happen ‘when any planner uses scanned inputs, forecasts, alternative future exploration analysis and feedback to produce or alter plans and actions of the organization’ [16].
\nStrategic foresight has been criticised due to its failure to make reliable predictions [4]. It is argued that although the predictions of strategic foresight are relatively accurate in the short run, forecasting accuracy is likely to diminish in the medium and long run due to the unpredictability nature of technological, economic, political and social drivers of change that work together in unusual and unanticipated ways. Therefore, reactive methodologies based on strategic agility and organisational flexibility have been encouraged under turbulent environments instead of planning.
\nHowever research has shown that there are certain circumstances under which foresight based approaches and planning are useful in helping the alignment of strategic decisions with changing environments. Furthermore, there are also circumstances under which flexible approaches are useful. For instance, in a study conducted on strategic planning and organisational flexibility in turbulent environments, it was found that in the case of continuous drivers of change that do not result in boundary uncertainty, strategic foresight tools are useful. Organisations operating under such circumstances are therefore encouraged to invest heavily in predicting changes and new events and align them with their goals. However the same study above also found that in the case of discontinuous change, which results in boundary uncertainty, managers should emphasise agility and stay flexible so that they adapt to environmental changes as they develop. The study also found that in the case of discontinuous change, foresight techniques and practices like product and technology road mapping can become sources of indolence which may lock managers ‘into the (wrong) future they predicted and thus distracting them from the real future’ [4].
\nThe above was the case of Nokia which was locked in its Symbian operating systems that it had invested so heavily in. Nokia had used environmental scanning, product and technology roadmaps to define its competitive position and developing its product portfolio in the mobile communication industry. However, Nokia was not able to sustain its advantage over Google and Apple which entered the market unexpectedly exploiting the software skills they had originally developed in the PC industry. This entry of Apple and Google into the market can be identified as an example of a discontinuous driver of change that results in boundary uncertainty. Thus under such circumstances, strategic flexibility and learning enable firms to grasp the new key components and players of their industry as soon as they emerge and adapt quickly.
\nThe above brings us to the issue of dynamic strategy which contends that strategic planning is dynamic and it involves a complex pattern for actions and reactions. Thus strategy making can thus be planned and partially unplanned.
\nA capability is defined as a ‘collection of organizational routines that enable a firm to perform some set of tasks on a repeated or consistent basis’ [17]. Capabilities are taken to encompass ‘organisational processes by which resources are utilised to create growth and adaptation within changing environments’ [18]. Capability identification, selection and creation is an important (practical) strategic decision whose competitive performance is equivalent to decisions about ‘which markets to enter, how a firm can position itself in the market, in which markets to exploit existing resource capabilities, what prices to charge, how to deter entry and other traditional strategic variables’ [19]. Thus in the same manner business organisations compete in markets for products, they also compete to create technological, operational and organisational capabilities that provide them with advantage in those product markets. This entails a positive correlation between decision about product market entry and position and decision capability creation [19].
\nIt has been argued that investments in capabilities create strategic options for competition in product markets, and the firm’s capability strategy is to make a choice of investments in different types of capabilities. From a capabilities perspective, the firm’s strategic problem has been regarded as that to choose among alternative investment paths for building capabilities that would underlie competitive advantage [20]. The formation of capabilities is a result of various kinds of activities that include autonomous learning by doing, business process redesign, experimentation, investments in human and physical capital, technology adoption and Research and Development projects [19].
\nIt has been posited that the firm’s capability strategy involves choosing between deepening their existing capabilities contrasted with broadening their capabilities collection to include new sets of capabilities and this has been demonstrated in the form of a map with some examples provided [19]. This map is shown in Figure 1.
\nMap for capability strategy choices. Source: Pisano [19].
The above author argued that companies’ investments in capabilities can either be specialised or generalised as indicated in the map. However it was posited that both specialised and generalised capabilities can be subjected to broadening and deepening investments. For example as shown in Figure 1, when Honda (well known for automobile production) engages in vehicle design simulation methods, this is a typical capabilities’ deepening investment. However when Honda engages in building capabilities in light jet design, this is a typical capabilities broadening investment.
\nLikewise Google’s expansion into auto designs is an example of broadening investment, whereas Google’s research and development on internet search is an example of deepening investment as shown in Figure 1.
\nDynamic has been defined as the ‘capacity to renew competences so as to achieve congruence with the changing business environment’ [21]. Thus dynamic capabilities are taken to represent the ‘firm’s ability to integrate, build and reconfigure internal and external competences to address rapidly changing environments’ [21].
\nAs explained earlier on, the essence of dynamic capabilities emerged after the realisation through research that sustainable advantages suggested by traditional strategy theories are rare, short-lived and may be fortuitous [7]. As a result, dynamic capabilities and organisational capabilities were regarded as sources of sustainable competitive advantage. However it should be pointed out that there has been no empirical evidence established to the effect of the sustainability of capabilities over extended periods, though it has been established that inertia and complacency weaken the sustainability of dynamic capabilities [7].
\nThe dynamic capabilities theory is regarded as an extension to the Resource Based View (RBV) framework which argues that competitive advantage is a result of the firm’s ability to manage its internal resources. This is because some resources are regarded as firm specific, not transferrable and difficult to imitate. Thus in the RBV framework, a firm is regarded as a ‘collection of resources that are valuable, rare, imperfectly imitable and non-substitutable’ [22]. However, the RBV has been criticised on the grounds that while it identifies mechanisms that build competitive advantage, it does not explain how these mechanisms operate [22].
\nDynamic capabilities are a framework that is used to understand differences in firm level capabilities. The framework holds that firm level differences in capabilities are rooted in three factors namely asset positions, processes and paths which are explained below.
Asset positions—which hold that a firm’s ability to change the future range of capabilities is constrained by its current stock of capabilities. Here assets refer to the legacy resources namely organisational competences, technical skills and knowledge that determine the firm’s options for future capability expansion.
Processes—which refer to aspects like management systems, resource allocation processes and governance structures that shape organisational adaptability. It is this capacity to reconfigure a firm’s asset positions and specifically the processes that underlie this capacity that led to the formation of the construct called dynamic capabilities.
Paths—which hold that since most capabilities develop over time and are cumulative in nature, they involve commitments to ‘paths’ instead of discrete projects. This entails firms to engage themselves in paths for capability that lead to competitive advantage.
It is believed that capability differentials across firms is mainly a result of management choices, and management must be able to influence the creation and evolution of their firms’ capabilities. Thus management discretion in the selection of paths, together with some constraints faced can result in differences in firm capabilities. The dynamic capabilities approach can be used to explain firm level differentials and it also assists managers in making capability decisions. The approach helps to explain why some firms are more adaptive than others. More flexible firms are likely to do better in uncertain environments.
\nIn conclusion, it can be posited that, in a dynamic business environment, traditional tools for copying with strategic planning are necessary but not sufficient in ensuring business sustainability. Furthermore the nature of changes experienced determine the strategic approaches adopted by managers. Managers should also make proper capabilities decisions that will enable their firms to cope with uncertainty experienced in their business environments.
\nIf your research is financed through any of the below-mentioned funders, please consult their Open Access policies or grant ‘terms and conditions’ to explore ways to cover your publication costs (also accessible by clicking on the link in their title).
\n\nIMPORTANT: You must be a member or grantee of the listed funders in order to apply for their Open Access publication funds. Do not attempt to contact the funders if this is not the case.
",metaTitle:"List of Funders by Country",metaDescription:"If your research is financed through any of the below-mentioned funders, please consult their Open Access policies or grant ‘terms and conditions’ to explore ways to cover your publication costs (also accessible by clicking on the link in their title).",metaKeywords:null,canonicalURL:"/page/open-access-funding-funders-list",contentRaw:'[{"type":"htmlEditorComponent","content":"Book Chapters and Monographs
\\n\\nMonographs Only
\\n\\nBook Chapters and Monographs
\\n\\n\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\nMonographs Only
\\n\\nLITHUANIA
\\n\\nBook Chapters and Monographs
\\n\\n\\n\\nBook Chapters and Monographs
\\n\\n\\n\\nBook Chapters and Monographs
\\n\\n\\n\\nSWITZERLAND
\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\\n\\n\\n\\nBook Chapters and Monographs
\\n\\nBook Chapters and Monographs
\n\nMonographs Only
\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\nBook Chapters and Monographs
\n\nBook Chapters and Monographs
\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\nBook Chapters and Monographs
\n\n\n\nMonographs Only
\n\n\n\nLITHUANIA
\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\n\n\nSWITZERLAND
\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\n\n\nBook Chapters and Monographs
\n\n