Investigation the Effect of Niobium Oxide Additive on the Dielectric Properties of Bismuth Titanate

Bismuth titanate ceramic has been attracted as a lead-free ferroelectric due to its high Curie temperature in high temperature applications as well as high frequency applications. In this study, the effect of niobium oxide as an additive on the microstructure and dielectric properties of bismuth titanate ceramic was investigated. For this purpose, niobium oxide was added to bismuth titanate, synthesized by the solid state method, in the amounts of 0.3, 0.6 and 1.2 mole %. The results showed that niobium oxide has a significant effect on the microstructure and dielectric properties of bismuth titanate ceramic. The addition of niobium oxide improved the density and the densification of bismuth titanate ceramics. For a sample containing mole % of niobium oxide, the highest density was obtained at 98% of the theoretical density. The amount of 0.6 mole % of niobium oxide is reported as the optimal value. In this sample, the highest dielectric constant (420) and the least amount of dielectric loss (0.04) were obtained. Also, the dependence of the dielectric properties of this sample on the frequency was less than bismuth titanate. Improvements in the dielectric properties of bismuth titanate can be attributed to grain growth and higher density by the addition of niobium oxide additive. The results of this study show that the grain size of bismuth titanate ceramic will have a significant effect on dielectric constant and dielectric loss.