Influence of Phase Composition on Dielectric Properties of Bismuth-Based Ceramics with Scheelite-Type Structure

Goal of the present research was to study dielectric properties of BiNbO4 ceramics fabricated by solid state reaction route followed with pressureless sintering. The samples were fabricated from the mixture of oxides, viz. Nb2O5 and Bi2O3. Apart from stoichiometric amount an excess of 3%, 5% and 10% by mole of Bi2O3 was used. It was found that an excess amount of Bi2O3 oxide caused formation of Bi5Nb3O15 minor phase in amount of 9wt%, 18wt% and 25wt%, respectively. The dielectric properties were studied by impedance spectroscopy within the frequency range nu= 20Hz-1MHz and temperature range T=RT-550 degrees C. It was found that the presence of the minor phase in amount of 18wt% caused a decrease in dielectric losses of the material under studies.