Novel high-T_C piezo-/ferroelectric ceramics based on a medium-entropy morphotropic phase boundary design strategy

The medium- or high-entropy strategy has emerged as a new paradigm for designing high-performance piezoelectric ceramics. However, the effectiveness of this approach remains unclear to the development of high Curie temperature (T_C) piezo-/ferroelectric materials with outstanding performance. To develop high-performance piezo-/ferroelectric materials suitable for high-temperature environments, in this work, we design a novel ceramic system based on a medium-entropy morphotropic phase boundary (ME-MPB) strategy. Piezo-/ferroelectric ceramics of the formula, Pb(Yb_1/2Nb_1/2)O₃-Pb(In_1/2Nb_1/2)O₃-PbTiO₃, meeting the medium entropy criteria, were successfully synthesized using the conventional solid-state reaction method. The crystal structure, microstructure, dielectric, piezoelectric, and ferroelectric properties of the ceramics of the ME-MPB compositions were systematically investigated. X-ray diffraction and scanning electron microscopy analyses revealed that these ceramics possess a pure perovskite phase and dense microstructure. Notably, the prepared ceramics exhibited exceptional piezoelectric performance, with a high d₃₃ up to 603 pC/N, a large strain of 0.20%, a high remanent polarization of 44.0 μC/cm², and a high Curie temperature of 362 °C. This study demonstrates an effective design approach based on the ME-MPB strategy and points out a new pathway for developing high-performance materials for high-temperature applications as sensors, thereby expanding the research perspective on the design of medium-entropy piezo-/ferroelectric ceramics.