Navdeep Goyal

By Kuldeep Chand Verma, Ashish Sharma, Navdeep Goyal and Ravinder Kumar Kotnala

Multiferroic magnetoelectric material has significance for new design nano-scale spintronic devices. In single-phase multiferroic BaTiO3, the magnetism occurs with doping of transition metals, TM ions, which has partially filled d-orbitals. Interestingly, the magnetic ordering is strongly related with oxygen vacancies, and thus, it is thought to be a source of ferromagnetism of TM:BaTiO3. The nanostructural MFe2O4 (M = Mn, Co, Ni, Cu, Zn, etc.) ferrite has an inverse spinel structure, for which M2+ ions in octahedral site and Fe3+ ions are equally distributed between tetrahedral and octahedral sites. These antiparallel sub-lattices (cations M2+ and Fe3+ occupy either tetrahedral or octahedral sites) are coupled with O2- ion due to superexchange interaction to form ferrimagnetic structure. Moreover, the future spintronic technologies using diluted magnetic semiconductors, DMS materials might have realized ferromagnetic origin. A simultaneous doping from TM and rare earth ions in ZnO nanoparticles could increase the antiferromagnetic ordering to achieve high-Tc ferromagnetism. The role of the oxygen vacancies as the dominant defects in doped ZnO that must involve bound magnetic polarons as the origin of ferromagnetism.

Part of the book: Electromagnetic Materials and Devices

By Amardeep Bharti and Navdeep Goyal

Synchrotron radiations are emerging as a real-time probing tool for the wide range of applied sciences. Synchrotron radiations have unique properties because of their high brilliance, collimations, broad energy spectrum, and coherence power that break the limits to characterize the material properties than previous laboratory-based tabletop sources. The third-generation synchrotron light sources are capable of producing 1012 times higher brilliance than laboratory-based sources using insertion devices. In this chapter, the fundamental aspects of synchrotron radiations and their generation process have been discussed. The effect of insertion devices and the double-crystal monochromator (DCM) toward the X-ray beam optics has been also discussed.

Part of the book: Synchrotron Radiation

By Kuldeep Chand Verma and Navdeep Goyal

Recently invented hydroelectric cell (HEC) is emerging as a better alternative for green electrical energy devices. HEC is fabricated as to generate electricity via splitting of water into H3O+ and OH− ions without releasing any toxic product. In iron oxides, Hematite (α-Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3) nanoparticles HEC are recently reported for their remarkable electrical response by splitting water molecules. Fe3O4 HEC 4.8 cm2 surface size has delivered 50 mA short circuits current. Li ions into Fe3O4 stabilize electrical cell response to 44.91 mA with open-circuit voltage 0.68 V. Maghemite based HEC delivered a maximum short circuit current 19 mA with emf 0.85 V using water 200 μL. Maximum off-load output power 27.6 mW has been delivered by 4.84 cm2 area hematite-HEC which is 3.52 times higher with 7.84 mW power as generated by Li-Mg ferrite HEC. Maximum electrical power 16.15 mW delivered by maghemite HEC is 0.58, 0.42 times lower than respective magnetite, hematite HECs. In more applicability of iron oxides, the multiferroic nanocomposites of BaTiO3 with 85% CoFe2O4 has been shown maximum short circuit current 7.93 mA and 0.7 V emf by sprinkling few drops of water on HEC surface. Li0.3Ni0.4Fe2.3O4 and Mg0.8Li0.2Fe2O4 HECs also have some remarkable results for green energy generation.

Part of the book: Iron Oxide Nanoparticles