Relaxor properties of 0.65 K0.5Bi0.5TiO3–0.35 BaTiO3 ceramics

Abstract

In this study, 0.65 K0.5Bi0.5TiO3–0.35 BaTiO3 (KBT–BT3) ceramics were synthesized using two methods: a conventional calcination process (CC-process) and a two-step calcination process, which combined the hydrothermal and CC processes (HT-CC-process). The effects of the different calcination processes on the physical and dielectric properties of the KBT–BT3 ceramics were recorded and analyzed. Secondary phases, namely BaBi4Ti4O15 and K4Ti3O8, were observed in the X-ray diffraction patterns (XRD) of the 1075–1125°C-sintered CC-process KBT–BT3 ceramics. Only the secondary BaBi4Ti4O15 phase was observed in the XRD pattern of the 1125°C-sintered HT-CC-process KBT–BT3 ceramics. However, as the sintering temperatures of the CC-process and HT-CC-process KBT–BT3 ceramics were lower than 1075°C and 1125°C, only the KBT–BT3 phase was observed. It demonstrated that these secondary phases inhibited grain growth and lead to KBT–BT3 ceramics with worse dielectric properties. The Curie–Weiss and modified Curie-Weiss laws were used to explain the phase transitions of the CC-process and HT-CC-process KBT–BT3 ceramics. We found that the CC-process and HT-CC-process KBT–BT3 ceramics sintered at all temperatures revealed the relaxor-typed ferroelectric characteristics.