Temperature dependent electrocaloric performances in Pb0.97La0.02(Hf0.92Ti0.08)O3 antiferroelectric ceramic with triple phase structures

Antiferroelectric–ferroelectric phase transition in antiferroelectric (AFE) materials usually triggers high-performance electrocaloric effect (ECE), as represented by PbZrO3-based AFE. As an isostructure to PbZrO3, EC research in PbHfO3-based AFE ceramics are significantly left out. In this work, temperature dependent electrocaloric performances in Pb0.97La0.02(Hf0.92Ti0.08)O3 with typical AFE features are explored, and rhombohedral ferroelectric (FER), AFE1 (A1, Pbam), and AFE2 (A2, Imma) triple phases are induced as temperature increases. This leads to dual coexisting regions with FER-to-A1 and A1-to-A2 at a temperature of ∼20 °C and ∼100 °C, respectively, where local EC maxima are produced with an ΔT ∼0.06 K and ΔT ∼0.16 K (E = 70 kV/cm). These are certified by comprehensive characterizations of in situ x-ray diffractometer, AFE electrical properties, and Raman spectra analysis. This strongly indicates that AFE (Pbam)-to-AFE (Imma) phase transition could efficiently optimize ECE in PbHfO3-based AFE, in addition to the conventional understandings of FE–paraelectric and AFE–paraelectric modulation strategy. This work not only presents the potential of PbHfO3-based AFE in solid-state cooling applications but also serves as a catalyst for further seeking for high-EC AFE materials.