Achieving improved electrocaloric effect and broad operation temperature by tailoring phase fraction in BaTiO₃-based ceramics

Ferroelectric electrocaloric (EC) materials are a pivotal part of sustainable micro-cooling, which complements conventional cooling methods in miniaturized devices. However, the application of EC materials is largely limited by the unsatisfactory room-temperature EC response and narrow operation temperature window. In this work, with careful tuning the composition of BaTiO3 (BT)-based ceramics through the conventional doping method, enhanced EC properties were achieved in Ba0.8Sr0.2Zrx(Ti0.999Mn0.001)(1-x)O-3 (BSZMT) (x = 0.05, 0.10, 0.15, and 0.20). We especially found that the electrocaloric temperature change (Delta T) of > 0.50 K was achieved in a broaden temperature ranging from 20 degrees C to 95 degrees C and a peak Delta T value of 1.08 K was achieved at temperature of 70 degrees C in our BSZMT with x = 0.15. To ascertain the physical mechanism, we employed hybrid characterization methods including XRD, Raman, and dielectric analysis together with Density Functional Theory (DFT) calculation. Our results clearly show that the doped Zr and Mn at B site of BSZMT effectively modulate the microstructure leading to coexistence of different ferroelectric phases and broken long-range ferroelectric order, which subsequently results in the enhanced EC performance and broad operating temperature window.