Effect of excess Bi₂O₃content on the sintering and dielectric characteristics of 0.65 (K_0.5Bi_0.5TiO₃)-0.35 BaTiO₃ceramic

In this study, K₂CO_3,Bi₂O₃, BaTiO₃, and TiO₂were mixed to form the compositions of 0.65 K_0.5Bi_0.5TiO₃-0.35 BaTiO₃+ x wt% Bi₂O₃(abbreviated as 0.65 KBT-0.35 BT3-x, x = 0, 1, 2, and 3). Excess Bi₂O₃was added into the 0.65 KBT-0.35 BT3 composition as the sintering aid to lower sintering temperature, to improve densification, and to compensate the vaporization of Bi2O3 during the sintering process. After being calcined at 850 °C for 2 h, 0.65 KBT-0.35 BT3-x ceramics were sintered at 1050 °C∼1100 °C in air for 2 h. The X-ray diffraction pattern and scanning electronic microscope observation were used to analyze the variations of crystalline phase and microstructure of the 0.65 KBT-0.35 BT3-X ceramics. Temperature-dependent dielectric characteristics were measured with oscillating amplitude (50 mV) at 100 KHz by an HP4294A impedance analyzer by putting the sintered ceramics in a temperature-programmable testing chamber from 25 °C to 500 °C. We would well investigate the effects of sintering temperature and excess Bi₂O₃content on the maximum dielectric constant and Curie temperature of the 0.65 KBT-0.35 BT3-x ceramics.