A systematic modification of the large electrocaloric effect within a broad temperature range in rare-earth doped BaTiO3 ceramics

Abstract

This paper presents a systematic exploration of modifying the electrocaloric effect (ECE) in BaTiO₃ ceramics by rare-earth substitution (Ba_0.94R_0.04TiO₃, R = La, Ce, Nd, Sm, Eu, Gd, Dy, Er). All samples exhibit a dense microstructure after sintering in the temperature range of 1350–1450 °C, and they exhibit a high resistivity of ∼10¹¹ Ω cm except for Er doped samples due to the amphoteric incorporation of Er. The rare-earth doping changes the lattice symmetry where the tetragonal distortion enhances with the decrease in the rare-earth ionic radius. Accordingly, the ferroelectric and ECE properties are modified and the first-order phase transition is diffused. The Curie temperature and latent heat increases, and the polarization intensity is strengthened with the decrease of the doping ionic radius, while the peak of ECE ΔT widens and shifts to a higher temperature. The samples show a large ECE value of ∼0.35 K m MV⁻¹ over a wide temperature range from room temperature to 140 °C, which provides a series of top-level ECE materials.