Influence of Ca doping on thermal and electrical properties of BiFeO₃

In this work, the effect of Ca doped BiFeO₃ was investigated focusing on its microstructure, thermal and electrical properties. The compound BiFeO₃ was prepared by solid state reaction at high temperatures. Samples of Ca-doped BiFeO₃, Bi_1-xCa_xFeO₃ with 0≤x≤0,5, were obtained by the same method of synthesis. Conventional sintering of compacts was carried out under specific conditions of temperature and holding time in order to maximize their density. The hybrid microwave sintering technique was also used to determine its influence on densification and on its microstructure. X-ray diffraction was used to study the crystalline structure of the obtained materials. The microstructure was observed using a scanning electron microscope. Thermal analyses allowed for identifying thermal events related to the Curie and Néel temperatures. Electrical measurements were carried out by impedance spectroscopy. The obtained results allowed to obtain an optimized route for preparing BiFeO₃ with good density by the conventional method. In addition, they allowed for a better understanding of the influence of Ca on thermal, structural, electrical and dielectric properties of the compound. (author)