Giant Electrocaloric Effect and Ultrahigh Refrigeration Efficiency in Antiferroelectric Ceramics by Morphotropic Phase Boundary Design

Abstract

Electrocaloric effect (ECE) in ferroelectric (FE)/antiferroelectric (AFE) materials offers a promising high-efficient and zero-emission solid-state cooling technology, whose materials design is usually focused on the morphotropic phase boundary (MPB) between two FE phases. This work constructs an MPB between an orthorhombic AFE and a rhombohedral FE phase in Pb 0.97−x Ba x La 0.02 Zr 0.95 Ti 0.05 O 3 (PBLZT100x, x = 0−0.08) ceramics and achieves a superior ECE performance. An unprecedented high electrocaloric strength of 1.52 K•mm/kV and an ultrahigh refrigeration efficiency (coefficient of performance = 16) are obtained in PBLZT4, in the MPB near AFE end. Moreover, a large negative ECE, with the highest strength up to −0.41 K•mm/kV, is also realized due to the electric field-induced AFE−FE transition. The coexistence of giant positive and negative ECEs at adjacent temperatures can further improve the cooling capacity (∼17%) of solidstate refrigeration in a well-designed cooling cycle. This work provides a brand new materials design strategy to achieve giant positive and negative ECEs simultaneously and a novel cooling cycle to efficiently utilize the two effects.

Room‐Temperature Symmetric Giant Positive and Negative Electrocaloric Effect in PbMg0.5W0.5O3 Antiferroelectric Ceramic

“…d) Comparison of the phase transition enthalpy as a function of transition temperature of PMW ceramic with other FE/AFE perovskite ECE materials. [ 11,13,15,18,20 ] e) Schematic diagram showing the structure of PMW ceramic in the AFE and PE phases.…”

Near‐Room‐Temperature Large Electrocaloric Effect in Barium Titanate Single Crystal Based on the Electric Field–Temperature Phase Diagram

“…Similar phenomena were also found in the 0.7Pb(Mg 1/3 Nb 2/3 )O 3 -0.3PbTiO 3 (PMN-PT) single crystal and PbZrO 3 -based anti-FE ceramic. [13,21] It usually suggests an electric-field-induced phase transition. For the BaTiO 3 single crystal, once the electric field increases to AE21.5 kV cm À1 , a discontinuous increase in polarization emerges, indicating a transition from T to O phase.…”

“…It has attracted much attention and become a frontier topic in ferroelectric (FE) scope since the landmark works of giant EC response reported in PbZr 0.95 Ti 0.05 O 3 thin film and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) film. [6,7] The following EC researches involve all kinds of FE material systems (BaTiO 3 , [8][9][10] Pb(ZrTi)O 3 , [11][12][13] BiFeO 3 , [14] Na 0.5 Bi 0.5 TiO 3 , [15][16][17] and (KNa)NbO 3 [18][19][20] ) and sample forms (single crystals, [21][22][23] ceramics, [9,24,25] films, [26][27][28] and multilayer ceramic capacitors (MLCCs) [29][30][31] ). Due to the high polarizability of Pb 2þ , the lead-based FE materials usually exhibit outstanding polarization characteristics, yielding excellent EC effects.…”

“…Due to the high polarizability of Pb 2þ , the lead-based FE materials usually exhibit outstanding polarization characteristics, yielding excellent EC effects. [11,13,30,32] However, they are severely restricted due to the toxicity of Pb on ecological and human health. This emphasizes the urgency of exploiting the large EC effect in lead-free materials, among which BaTiO 3 -based FE materials are one of the promising candidates.…”

Adjustable giant negative electrocaloric effect in Pb1+xZrO3 thin films

“…al. obtained the large ECE and high coefficient of performance in PZO-based morphotropic phase boundary (MPB) ceramics [16]. Large ΔT of about -10 K was obtained in 1.0 mol% Yb doped and Nb and Sn co-doped PZO thin films [17,18].…”