Synergistic effects of grain orientation and microstructure modification in PMN-PT electrocaloric ceramics

Grain orientation engineering is an effective approach to tailor the electrical properties in ferroelectric ceramics. Although it was found that the electrocaloric (EC) performance can be affected due to grain orientation design in literatures, the grain microstructure modification in textured EC ceramics was rarely emphasized. Here, 0.90 Pb(Mg_1/3Nb_2/3)O₃‒0.10PbTiO₃ (PMN-10PT) ceramics with <111> orientation were fabricated. A combination approach of texturing and grain structure modification was designed. An optimization of two-step sintering process was utilized to obtain the <111>-textured ceramics with dense body and relatively uniform grain structures. Compared to normal (single-step) sintered ceramics, the dielectric breakdown strength of the <111>-textured PMN-10PT ones sintered by two steps enhanced from 53 to 69 kV cm⁻¹. Especially, the <111>-textured ceramics synthesized via 1230°C/1200°C sintering process exhibited an enhanced adiabatic temperature ΔT change of 0.88 K when the applied field was 35 kV cm⁻¹, which improved EC performance by 39.7% compared to randomly oriented ceramics, and was also 11.4% higher than that of the conventionally sintered textured samples. This work analyzed the synergistic effect of texture and grain microstructure on the EC performance of PMN-PT ceramics, and provides a facile sintering method to further enhance the EC property of ferroelectric ceramics.