High pyroelectricity in lead-free 0.5Ba(Zr _0.2Ti _0.8)O ₃0.5(Ba _0.7Ca _0.3)TiO ₃ ceramics

We report high pyroelectricity in lead-free 0.5Ba(Zr _0.2Ti _0.8)O ₃0.5(Ba _0.7Ca _0.3)TiO ₃ (BZT50BCT) ceramics which were previously reported to exhibit high piezoelectricity. The pyroelectric coefficient measured by the ByerRoundy method upon heating for dc-poled samples shows a high value of 5.84×10 ⁴Cm ²K ¹ at 300K, comparable to those of PZT-based ceramics and significantly higher than many other lead-free pyroelectric materials. The pyroelectric coefficient calculated from the remanent polarization versus temperature relationship obtained during a cooling process is 17.17×10 ⁴Cm ²K ¹ at 300K, which is considerably larger than the value obtained by the ByerRoundy method. This difference is attributed to the thermal hysteresis of the rhombohedraltetragonal phase transition between the heating and cooling processes.