Potassium-sodium niobate(KNN)-based piezoelectric materials demonstrate exceptional electrocaloric(EC)optimization potential owing to phase configurational diversity,though current performance remains constrained by i...Potassium-sodium niobate(KNN)-based piezoelectric materials demonstrate exceptional electrocaloric(EC)optimization potential owing to phase configurational diversity,though current performance remains constrained by insufficient entropy modulation.This study establishes highentropy strategies-particularly phase/ion-configurational entropy(I-PCE)synergistic regulation-as a critical pathway to transcend conventional EC entropy change(ΔS_(ECE))limits.Phase-field modeling of Rhombohedral-Orthorhombic-Tetragonal-Cubic(R-O-T-C)phase evolution reveals thatΔSECE is governed by three hierarchical factors:phase configurational entropy(Sconfig_phase,dominant),ion configurational entropy(Sconfig_ion),and polarization response.Notably,polarization response in R-phase supersedes O-phase entropy contributions,establishing a performance hierarchy.Based on I-PCE optimization,R-O-dominated multiphase coexistence achieves aΔS_(ECE)exceeding 19 J/kg/K at 52.80μC/cm^(2)reversible polarization.Further achieving enhanced polarization(100μC/cm^(2))yields aΔS_(ECE)of 73 J/kg/K,establishing the experimental EC upper bound for KNN systems via high entropy-driven design.We anticipate that these discoveries will provide theoretical guidelines for tailoring EC effects in multiphase-configurational material systems via high-entropy strategies.展开更多
基金supported by the Youth Science Fund Project(Class C)of the National Natural Science Foundation of China under Grant No.52502152supported by the National Natural Science Foundation of China under Grant(No.52032007 and 51772211).
文摘Potassium-sodium niobate(KNN)-based piezoelectric materials demonstrate exceptional electrocaloric(EC)optimization potential owing to phase configurational diversity,though current performance remains constrained by insufficient entropy modulation.This study establishes highentropy strategies-particularly phase/ion-configurational entropy(I-PCE)synergistic regulation-as a critical pathway to transcend conventional EC entropy change(ΔS_(ECE))limits.Phase-field modeling of Rhombohedral-Orthorhombic-Tetragonal-Cubic(R-O-T-C)phase evolution reveals thatΔSECE is governed by three hierarchical factors:phase configurational entropy(Sconfig_phase,dominant),ion configurational entropy(Sconfig_ion),and polarization response.Notably,polarization response in R-phase supersedes O-phase entropy contributions,establishing a performance hierarchy.Based on I-PCE optimization,R-O-dominated multiphase coexistence achieves aΔS_(ECE)exceeding 19 J/kg/K at 52.80μC/cm^(2)reversible polarization.Further achieving enhanced polarization(100μC/cm^(2))yields aΔS_(ECE)of 73 J/kg/K,establishing the experimental EC upper bound for KNN systems via high entropy-driven design.We anticipate that these discoveries will provide theoretical guidelines for tailoring EC effects in multiphase-configurational material systems via high-entropy strategies.
