Decisive role of MgO addition in the ultra-broad temperature stability of multicomponent BaTiO3-based ceramics

High capacitance temperature stability (the capacitance is within ±15% of room temperature capacitance) in an ultra-broad temperature range of −55 °C to 300 °C has been achieved by synthesizing multicomponent BaTiO3-based ceramics consisting of BaTiO3, Na0.5Bi0.5TiO3, Nb2O5, CeO2, glass and MgO. Significantly, MgO addition plays a decisive role in achieving the ultra-broad temperature stability and acquiring an appropriate microstructure. Doping different amounts of MgO can alter the temperature dependence of dielectric constant markedly, especially in a high temperature range of 200 °C–300 °C. The maximum capacitance variation rate is reduced from −60% to only 10% by doping appropriate content of MgO. In terms of the microstructure, MgO additive can suppress the formation of Ti-rich phase and sheet grains, which are detrimental to the capacitance temperature stability. The sample with 1.5 wt% MgO has superior dielectric and electrical properties at room temperature (εr=1675, tan δ=1.452%, and ρV=5×1012 Ω cm).