Temperature stability of lead-free BST-BZN relaxor ferroelectric ceramics for energy storage capacitors

Low sintering temperature and good temperature stability are the crucial parameters for the actual application of the dielectric capacitors. In this work, lead-free relaxor ferroelectric ceramics with chemical formula (1 - x)(Ba0.4Sr0.6)TiO3-xBi(Zn2/3Nb1/3)O-3 [(1 - x)BST-xBZN, (x = 0.00 to 0.225)] were developed through a solid-state synthesis route. The microstructures, dielectric performance, and temperature stability were studied in detail. The results show that 0.775BST-0.225BZN bulk ceramic with capacitance-temperature dependence satisfied with X8R specification can be obtained at a sintering temperature of 1140 degrees C. In addition, the energy storage performance of 0.775BST-0.225BZN bulk ceramic exhibits good temperature stability in a wide range of temperatures from 25 to 150 degrees C. High dispersion results in capacitance-temperature stability and energy storage stability. More importantly, the 0.775BST-0.225BZN ceramic also displays good charge-discharge performance dependence on temperatures (variations of the current density and power density are less than 3% over 25-150 degrees C). These results demonstrate that 0.775BST-0.225BZN lead-free ceramic is a potential material for dielectric capacitors that can be operated in a wide range of temperatures.