Refinamento estrutural e cálculos de densidade eletrônica no sistema multiferróico (Bi1-xNdx)(Fe1-yCoy)O3

Abstract

The need for new technologies in our society caused a greater interest in research on materials used in electronics applications, it made the multiferroic crystalline materials very promising and of great and technological academic interest materials due to correlation between the ferroelectric and (anti )ferromagnetic properties. Among these materials, compounds with perovskite structures, as those arising from the doping of BiFeO3 can be mentioned. In this work ceramic powders of (Bi1-xNdx)(Fe1-yCoy)O3 compositions, for (x = 0.0, 0.1 and 0.2) and (y = 0.0, 0.01 and 0.02), were processed using high-energy ball-milling followed by sintering in a free atmosphere. Also it was used the fast sintering technique followed by quenching. By using the X-ray diffraction technique, and structural refinement via Rietveld method it is concluded that all compositions have rhombohedral symmetry with space group R3c. The electron density calculations allowed better analysis on the bonding character between the Bi3+/Nd3+ and O2- ions, and between the Fe3+/Co3+ and O2- ions in the (Bi1-xNdx)(Fe1-yCoy)O3 compositions. We could observe that with the addition of cobalt ions the bonding between iron and oxygen ions tend to become more covalent. This did not happen with the bonding between bismuth and oxygen ions. For neodymium doped samples, we observed for x = 0.1 the complete disappearance of the covalent bond (Lone Pairs) between the bismuth and oxygen ions and a significant increase in covalency between iron and oxygen ions