Magnetic and Electrical Properties of Pure and Substituted Bismuth Ferrites

Abstract

Multiferroic materials can be considered as materials presenting at least two or more than two ferroic states simultaneously. Because of room temperature multiferroic properties, most of research has been concentrated on BiFeO3 (BFO) and its derivatives. The objective of this thesis work is to synthesize stoichiometric pure-phase BFO nanoparticles using various complexing agents and to enhance its multiferroic properties by site-engineering. The overall chapters comprise the general introduction to basic concepts, some historical aspects and possible applications of multiferroics. A detailed introduction to the titled compound BFO, with its structural, electrical and magnetic properties has been described. The different experimental techniques like sol-gel synthesis method, X-ray diffraction, TEM, SEM, ferroelectric, magnetic, dielectric, leakage current analysis etc.The pure BFO nanoparticles preparing using various complexing agents like citric acid, malonic acid, succinic anhydride and tartaric acid by sol-gel method annealed at different temperatures followed by structural, electrical and magnetic characterizations. The structural, magnetic and ferroelectric properties Gd doped BFO samples prepared by sol-gel method. The polarization approaches ~ 0.35and#956;C/cm2 for Bi0.85Gd0.15FeO3.Next is describes preparation and characterization of pure and Sm/Co dopedBFO samples. Co-doping of Sm and Co in BFO had a significant improvement on the magnetic, electrical and ferroelectric properties. The structural, magnetic, ferroelectric, dielectric and leakage current density studies of Gd, Mn, Co and Cr doped bismuth ferrites samples. It is observed that Gd-doping increases the symmetry and decreases the second phases noticeably. Magnetic and electrical properties increase considerably in doped BFO samples. Finally, the thesis summarizes the results obtained in the present investigations with comparison from literature and future course of work on present investigations.