Fabrication and Study of BiNbO_4 Ceramics

摘要

Aim of the present research was to fabricate and study crystalline structure as well as dielectric properties of BiNbO_4 ceramics. In the present study BiNbO_4 ceramics was fabricated by solid state reaction from the mixture of simple oxides viz. Bi2O_3, and Nb_2O_5. Stoichiometric mixture of the powders was thermally analyzed so parameters of the thermal treatment were determined. The EDS measurements proved conservation of the chemical composition of the ceramic powder after calcination (T=800°C). Free sintering at T=870 - 1080 °C was used for fabrication of the ceramic samples. Morphological analysis using scanning electron microscopy was performed. The crystalline structure of the sintered samples were examined by X-ray diffraction method at room temperature. It was found that for low temperature of sintering (T<1000 °C) bismuth niobate crystallized in orthorhombic symmetry Pnna (52) whereas for high sintering temperature (T>1000 °C) BiNbO_4 exhibited anorthic symmetry P-l (2). Low frequency (v=100Hz - 1MHz) impedance spectroscopy was applied to study influence of the sintering temperature on dielectric properties of bismuth niobate at room temperature. The equivalent circuit method was used for analysis of the impedance data.