Large Room-Temperature Electrocaloric Response Realized in Potassium-Sodium Niobate by a Relaxor Enhancement Effect and Multilayer Ceramic Construct

Abstract

The development of high-performance electrocaloric (EC) materials is crucial for solid-state refrigeration applied in micro-electromechanical systems. Herein, a large room-temperature EC response is realized in (1 – x)­(K0.49Na0.49Li0.02)­(Nb0.8Ta0.2)­O3–xCaZrO3 (KNLNT–xCZ) benefiting from a relaxor enhancement effect and multilayer ceramic construct. The relaxor enhancement effect is because the long-range order is broken by adding CaZrO3, which is in favor of enhancing the temperature change (ΔT) and broadening the temperature span (T span) at room temperature. A ΔT of 0.48 K in the KNLNT–12CZ ceramic is ∼5 times higher than that in the KNLNT–8CZ ceramic at 30 °C. KNLNT–12CZ also exhibits good temperature stability, and the T span is up to 65 K. In addition, the multilayer ceramic construct improves the breakdown electric field (E b) through diminishing defects, leading to a booming ΔT of 3.2 K at 30 °C under 250 kV cm–1 via a direct measurement. The work proposes an avenue for developing high-performance EC materials with a large EC response and broad T span in solid-state refrigeration.

Optimized Electrocaloric Refrigeration in Lead-Free NaNbO3-Based Ceramics via AFE ↔ FE Phase Transition Modulation

“…(c) Evolution of O distortion with increasing temperature and the temperature dependence of E C , E AF , and E FA for the NN-0.02CZ ceramic. (d) Comparison of EC performance (Δ T vs T span ) of AFE and FE ceramics (NN-based, ,,, BaTiO 3 -based, ,, Na 0.5 Bi 0.5 TiO 3 -based, , (K, Na)­NbO 3 -based, , and lead-based − ).…”

New Soft Actuating Way by Rapidly Temperature Change of Electrocaloric Effect

“…To be practical for cooling applications, EC materials should exhibit a large adiabatic Δ T and low working temperature near room temperature. In ferroelectrics, relaxor ferroelectrics (RFEs) exhibit a high EC response at room temperature and a broad T span due to polar nanoregions . Poly­(vinylidene fluoride) (PVDF)-based copolymers and terpolymers are a type of organic RFEs that have undergone significant improvements since their initial discovery.…”

“…In ferroelectrics, relaxor ferroelectrics (RFEs) exhibit a high EC response at room temperature and a broad T span due to polar nanoregions. 7 Currently, the EC effect is mostly used in cooling devices that require external action mechanisms to assist in heat transfer, with little focus on heating processes. 9,10 In addition to temperature management, EC materials can find use as driving elements in thermal-driven soft actuators.…”

Order-degree-modulated ferroic response and an unconventional electrocaloric effect in B-site complex systems: a case study in Pb[(Yb1/2Nb1/2)0.84(Mg1/3Nb2/3)0.16]O3 ceramic

“…ECE research received a tremendous boost after a giant ∆T of 12 K was reported in inorganic Pb(Zr 0.95 Ti 0.05 )O 3 and poly(vinylidene fluoride-co-trifluoroethylene) copolymer thin films [8,9]. ECE in relaxor ferroelectrics (FEs) [10][11][12][13][14][15], antiferroelectrics (AFEs) [16][17][18], polymers [19][20][21][22][23], polymer-ceramic composites [24][25][26] and multilayer capacitors [27][28][29][30] were soon explored. Also, electrocaloric (EC) prototype devices were developed [31][32][33][34][35] and great progress has been made in EC phase-field models [36][37][38][39].…”