High electrocaloric effect in hot-pressed Pb_0.85La_0.1(Zr_0.65Ti_0.35)O₃ ceramics with a wide operating temperature range

The temperature stability of the electrocaloric effect (ECE) in relaxor ferroelectric Pb_0.85La_0.1(Zr_0.65Ti_0.35)O₃ (PLZT) prepared by the hot-press sintering method has been investigated. Compared to the PLZTs prepared via the conventional sintering process, the hot-pressed PLZTs exhibit larger ECE and superior temperature stability. The hot-pressed sample with an appropriate content of excess PbO presents a high ΔT of 2.4°C and ΔS of 2.3 J kg⁻¹·K⁻¹, both of which are 30% greater than those of the conventionally sintered samples measured at 100 kV·cm⁻¹. More importantly, the hot-pressed specimens display great stable electrical properties, including the dielectric breakdown strength and electrical resistivity in the temperature range from 0°C to 100°C, whose ECE instability, especially, is only one-half that of the samples prepared by the conventional solid-state method. In addition, the ECE and its stability of the hot-pressed sample can be further enhanced by increasing the operating electric field to a relatively high level of 200 kV·cm⁻¹. This work demonstrates hot-press sintering is an effective method to fabricate ferroelectric ceramics with high ECE as well as desirable temperature stability.