Mechanism of the Pyroelectric Response under Direct-Current Bias in La-Modified Lead Zirconate Titanate Stannate Ceramics

Dielectric and pyroelectric properties of Pb_0.97La_0.02(Zr_0.42Sn_0.40Ti_0.18)O₃ ceramics are investigated as functions of temperature and dc bias field. Induced and intrinsic pyroelectric coefficients p_ind and p₀ are calculated and analyzed. It is found that the sign, value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p₀ under applied biases. Polarization and depolarization processes under dc biases are analyzed. Besides the contribution of p_ind, the diffuse and decreased pyroelectric response under dc bias compared with that of an identical field poled sample without dc bias is mainly attributed to the depolarization process under dc bias.