Densiftcation and dielectric properties of hydrothermal BaTiO₃ with different sources of Bi₂O₃

Abstract

Recently we have shown the possibility of preparing highly dense BaTiO₃ ceramic by sintering hydrothermally prepared BaTiO₃ with small amount of Bi₂O₃ at 850°C. The powder compacts sintered to about 94% theoretical density when 5wt% Bi₂O₃ was used as sintering aid. In this paper, the effect of Bismuth addition in the form of Bi₂O₃ and Bi-solution on the sintering characteristics, microstructural evolution, and the resultant dielectric properties of the hydrothermal BaTiO₃ is discussed. From this study, three sets of ceramics with 3wt% equivalent of Bismuth oxide were prepared by sintering the compacts between 750–1000°C. Two sets of ceramics sintered to densities >90% theoretical with an average grain size <0.2μm. The K vs. T plots of these ceramics shows a broad maximum at around 110°C. However, the ceramics prepared from one of solution added batch, showed very different physical and electrical characteristics. For example, the powder compacts sintered to 97% theoretical densities at temperatures as low as 800°C. In K vs. T plot a sharp peak was observed at T>125°C.