BiFeO3 CERAMICS DENSIFICATION STUDY

Abstract

Bismuth ferrite (BiFeO3) is one of the very few materials possessing ordered both electrical dipoles and magnetic moments in very wide range of temperatures. That gives it tremendous opportunities for research and application. BiFeO3 precursor powders were prepared by auto-combustion and soft chemical synthesis methods using different organic compounds as fuels and complexing agents. They were calcined at 600 °C for 2 h, grinded, pressed and sintered at 800 °C for 1 h with quenching. XRD and SEM confirmed formation of very pure BiFeO3 perovskite phase, but problem with low density, which is characteristic for BiFeO3 ceramics, still remained. It doesn’t affect magnetic properties, but has strong influence on electrical and, through them, on multiferroic properties. To define actual, intrinsic properties of material, it is very important to obtain ceramics with densities close to theoretical. For this reason, many treatments were tried in order to raise samples’ densities: powder milling and homogenization, ultrasound, different pressures, various thermal treatments. Powders and ceramic samples were then characterized (particle size analysis, XRD, SEM). The densities of sintered BiFeO3 samples were measured. All the treatments had impact on ceramics density, but some also introduced secondary phases.