In this chapter we introduce stoichiometry and nonstoichiometry from crystal structure point of view along with some examples. We also discussed about the importance of nonstoichiometry in the application oriented research work and their use in the technological applications. We further discuss the ways to identify stoichiometry through various methods. We then introduce neutron diffraction and briefly describe how neutrons and X-ray interacts with matter and the difference in their interaction with matter. We then focus upon its (neutron) usability to identify nonstoichiometry by using some examples available in the literatures. High-temperature superconductivity-based research has seen the importance of neutron diffraction and scattering in identifying the structural modification which leads to superconductivity in the compounds.
In this chapter, we introduce a promising composite material, which can be used as a potential candidate in the field of charge storage, sensors, and spintronic devices. The structural, magnetic, and magnetodielectric properties of the pure cum composite samples are investigated. The Rietveld refinement of the X-ray data confirmed the presence of a single (A21am) and mixed phases (A21am + R-3c + Pbam) in the pure and composite sample, correspondingly. The SEM microstructure suggests the contrasting nature of the homogeneous and heterogeneous distribution of grains in the corresponding pure and composite sample. The magnetic properties of the composite sample increase due to the enhanced exchange interaction between the different magnetic ions. The frequency-dependent dielectric subjected to a constant magnetic field indicates the signature of magnetodielectric (MD) coupling for both the samples. The field variation of the MD loop shows the symmetric hysteresis loop in the composite due to the addition of magnetostrictive La0.67Sr0.33MnO3 and the non-collinear antiferromagnetic Bi2Fe4O9 phase. The maximum value of MD% (~0.12%) is enhanced by ~13 times in the composite than in the pure sample. Therefore, the improved MD coupling and symmetric switching of the MD loop of the composite make it a suitable candidate for low power consumption storage devices.
Part of the book: Smart and Advanced Ceramic Materials and Applications