Pyroelectric and impedance studies of the 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)TiO3 ceramics

Abstract

This work contributes towards the analysis of the pyroelectric behaviour of lead-free pyroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)TiO3 (BZT-BST) ceramics. The pyroelectric coefficient (3.4 × 10−4 C m−2 K−1 at 303 K) was obtained by the Byer-Roundy method. The pyroelectric figures of merit for current, voltage, detectivity and energy harvesting applications are discussed with respect to possible optimization of these parameters. All the above mentioned figures of merit are dependent on the permittivity and dielectric loss. Hence, impedance analysis was conducted to identify the dominant contributions in permittivity and dielectric loss. The activation energies for bulk and grain boundary are ~1.0 eV and ~1.2 eV, respectively, which indicates presence of mobile oxygen vacancies. The contribution of these processes to the dielectric loss in the temperature range of interest (300–340 K) is, however, very low. The permittivity and the dielectric loss are dominated by a strictly dielectric response resulting from the phase transition in the respective temperature range.