Microwave dielectric properties of bismuth layer-structured Ca2−xSrxBi4Ti5O18 (0 ≤ x ≤ 0.6) ceramics

Ceramics of five-layered Ca2Bi4Ti5O18 (CBT) exhibit relatively high dielectric constants at high frequency. In this study, Sr2+ ions were added to substitute Ca2+ ions so as to improve the microwave dielectric properties of CBT ceramics. Densification, microstructural evolution, and microwave dielectric properties of Ca2−xSrxBi4Ti5O18 (CSBT), with x ranging from 0.0 to 0.6, were investigated. Besides, relation of sintering temperature and microscopic structure was also investigated. With increasing levels of Sr2+ ions additions, the relative permittivity increases from 170 to 202 but Q × f decreases from 868 to 428 GHz. Typically, dielectric properties of εr = 180 and Q × f = 759 GHz were obtained for the Ca1.8Sr0.2Bi4Ti5O18 specimens sintered at 1,175 °C for 5 h.