Diffuse phase transition broadening negative electrocaloric temperature span in Sr-doped PbZr0.95Ti0.05O3 thin films

Abstract

Electrocaloric effect (ECE) is one of the basic features of ferroelectrics / antiferroelectrics. The positive ECE and negative ECE exhibit oppose thermal response to the variation of electric fields. This allows them to complement each other, enabling more diversified refrigeration regulation. To enhance the negative ECE and broaden its temperature range, this work investigates the impact of diffuse phase transitions in antiferroelectric Pb_1-xSr_xZr_0.95Ti_0.05O₃ (PSZT) films on LaNiO₃/Si substrates. Sr²⁺ doping reduces the unit cell volume and enhances antiferroelectricity, resulting in an increment of the ECE ΔT from −2.26 K to −3.38 K. Meanwhile, it breaks the long-range antiferroelectric order to achieve a local symmetry breaking, and promotes the diffusion of the antiferroelectric-ferroelectric phase transition to significantly broaden the temperature span of the negative ECE from 33 K to over 108 K. This work demonstrates that controlling the phase transition diffusion in PSZT films effectively enhances the performance of the negative ECE and broadens its temperature span, providing a strong support for in-situ chip cooling technology.