Crystal structure and physical Properties of $(Bi_{0.9}La_{0.1})FeO_3 - A(Fe_{0.5}Nb_{0.5})O_3$ multiferroic solid solutions (A=Ba, Sr, and Pb)

Abstract

Recent micro-nano electronic and magnetic researches about functional oxide materials were great attentions to investigate the novel multiferroics properties such as puzzled coupling effect between electric dipole- and magnetic spin-moment as well as their mutual interaction in one single-phase material. The prototype coupling examples were already known as electro-mechanical (Piezoelectric) and/or magneto-mechanical (Magnetostrictive) effect. However, in the single phase multiferroics; representing simultaneous Ferroelectricity/Ferromagnetism and their mutual spin/dipole interaction in one-phase was still not-fully exploited field in crystallographic, physical, and chemical point of views. In addition, combining of spontaneous electrical dipolar polarization and spontaneous magnetic spin momentum in a single-phase must be tremendous interesting research field not only in a crystallographic point of view but also the investigation of fundamental solid-state-physics of spin-dipole interactions and perturbations theory. The coupling effect; intrinsic turnover of electrical polarization by the disturbance of the magnetization or vice versa in single phase multiferroics, allows another additional degree of freedom for designing of the novel purpose of new device applications. In this thesis, we restrained the “multiferroics” as the single-phase multiferroics to distinguish the magneto-electric composite approach, which were investigated elsewhere likewise $Pb(Zr,Ti)O_3$ /Terfenol-D laminated composites. Therefore, this thesis demonstrated that the compositional systematic study of multiferroic solid solution of x $(Bi_{0.1}La_{0.9})FeO_3-(1-x)A(Fe_{0.5}Nb_{0.5})O_3$ (A=Ba, Sr, and Pb) (BLFO-BFNO, BLFO-SFNO, and BLFO-PFNO, respectively) ceramic system as room temperature stable multiferroic materials. For developing of natural multiferroic $BiFeO_3$ ceramics itself; which had cyclical spin canting of Antiferromagnetism and very unstable Ferroelectricity at room te...