Electrocaloric effect and pyroelectric energy harvesting of (0.94 − x)Na0.5Bi0.5TiO3-0.06BaTiO3-xSrTiO3 ceramics

Ceramics with the composition (0.94 − x)Na0.5Bi0.5TiO3-0.06BaTiO3-xSrTiO3 (NBBSTx) where x = 0.10, 0.15, 0.20, and 0.25 were synthesized by a conventional solid-state reaction method to investigate their electrocaloric effect (ECE) and pyroelectric energy harvesting (PEH) properties. The ferroelectric, dielectric, and pyroelectric properties of the prepared ceramics were measured and discussed. It is found that the strontium titanate (ST) content and bias field greatly affect the ferroelectric-relaxor transition. Increasing ST content lowers the depolarization temperature of the ceramics, and both the ECE and PEH behavior of the ceramics strongly depend on their ST content because of the composition-induced decrease of the ferroelectric-relaxor transition temperature. The present investigation demonstrates that the ECE and PEH properties of NBBSTx ceramics can be tuned by introducing ST. Furthermore, a high PEH density of 425 kJ/m3 is obtained for NBBST0.20, which is much higher than those of conventional Pb-based ferroelectrics.