Effects of different synthesizing processes on the dielectric and piezoelectric properties of 0.65(K0.5Bi0.5TiO3)–0.35BaTiO3 ceramics

In this study, 0.65(K0.5Bi0.5)TiO3–0.35BaTiO3 (KBT–BT3) ceramics were synthesized using two different methods: a conventional calcination process (CC-process) and a two-step calcination process that combined hydrothermal and CC processes (HT–CC-process). The effects of the differently synthesizing processes on the physical and dielectric properties of the KBT–BT3 ceramics were recorded and analyzed. Two secondary phases, BaBi4Ti4O15 and K4Ti3O8, were observed in the XRD patterns of the CC-process KBT–BT3 ceramics. The formations of BaBi4Ti4O15 and K4Ti3O8 compounds made the CC-process KBT–BT3 ceramics having poor dielectric properties. When the HT–CC-process was used and the KBT–BT3 ceramics were sintered at 1050–1100 °C, the secondary phases were not observed and only the (K0.5Bi0.5, Ba)TiO3 phase was observed in the XRD patterns. As same sintering temperature was used, the dielectric constants of the HT–CC-process KBT–BT3 ceramics were higher than those of the CC-process KBT–BT3 ceramics. Electromechanical coupling factors, such as the planar coupling factor (kp), thickness coupling factor (kt), and longitudinal coupling factor (k33), were also used to explain the effect of the different synthesizing processes on the properties of the KBT–BT3 ceramics.