Doping and grain size effects on pyroelectric properties of Ba _0.7Sr _0.3TiO ₃ for uncooled infrared bolometer

Ba _0.7Sr _0.3TiO ₃ (BST) ceramics with different dopants and various grain sizes were fabricated by the solid-state reaction process, and the doping and grain size effects on dielectric and dc bias field-induced pyroelectric properties were systemically investigated. When acceptors were added, the dielectric loss of the BST was decreased effectively, whereas the pyroelectric coefficient was decreased for the broadening of dielectric constant peaks. With the increase of the content of acceptors and the adding of donors simultaneously, the decrease of pyroelectric coefficient caused by the doping effect could be weakened. The dielectric and dc bias field-induced pyroelectric properties were also affected by the grain size effects dramatically. In this paper, the best pyroelectric coefficient of 105×- 10 ^-8C/cm ²°C and figure-of-merit of 22× - 10 ^-5Pa ^-0.5 could be obtained when the grain size was 1μm. The systemic investigation of doping and grain size effects would contribute to the development of high pyroelectric properties of BST for uncooled infrared detector.