Synthesis and Characterization of Bismuth Ferrite Based Multiferroic Materials

Abstract

The thesis presents ferromagnetic, ferroelectric and magnetoelectric effect of single phase multiferroics and multiferroic composites. The single phase multiferroics presented in the present work are (Zr, Cu), (Dy, Cu), (Gd, Cu) and (La, Cu) co-doped BiFeO3. The multiferroic composite studied in this work are (Dy, Cu) BiFeO3-BaTiO3 composite and (Zr, Cu) BiFeO3-BaTiO3. In the present work, single phase multiferroic materials were synthesized by sol-gel method and their ferromagnetic and ferroelectric properties were studied to determine the effect of doping. Among the single phase multiferroic materials, enhanced magnetic properties are observed for the (Dy, Cu) and (Zr, Cu) co-doped BFO when compared to (La, Cu) and (Gd, Cu) co-doped BiFeO3. When Dy and Zr substitution to Bi site is increased, the saturation magnetization and remnant magnetization shows a remarkable increase. Hence, the (Dy, Cu) and (Zr, Cu) doping has improved the ferroelectric properties of the BFO. The measured magnetoelectric effect has shown more enhancement for the (Zr, Cu) doped BiFeO3 than that of (Dy, Cu) co-doped BiFeO3 multiferroic. The measured magnetic and ferroelectric properties of the doped samples have demonstrated to prove that (Dy, Cu) and (Zr, Cu) doping can significantly improve the multiferroic properties of BiFeO3. The results are attractive for the applications in ferroelectric random access memories. Hence, 0.85Bi0.95Dy0.05Fe0.98Cu0.02O3-0.15BaTiO3, 0.85Bi0.95Dy0.05FeO3-0.15BaTiO3, 0.85Bi0.95Zr0.05Fe0.98Cu0.02O3-0.15BaTiO3 and 0.85Bi0.95Zr0.05Fe0.98O3-0.15BaTiO3 multiferroic composites were prepared by solid state reaction method. The measured magnetic properties of the co-doped (Dy, Cu) BiFeO3-BaTiO3 composite, (Zr, Cu) BiFeO3-BaTiO3 composites, (Dy) BiFeO3-BaTiO3 composite and (Zr) BiFeO3-BaTiO3 single doped composite materials shows more development for the single phase doped BiFeO3 multiferroic. Enhanced magnetoelectric coupling effects were observed in 0.85Bi0.95Zr0.05Fe0.98Cu0.02O3-0.15BaTiO3 composite when compare