Electrocaloric effect(ECE)is promising in realizing solid-state cooling as an alternative to the conventional refrigeration with environmentally harmful coolant and low efficiency.High ECE in lead-free ferroelectric c...Electrocaloric effect(ECE)is promising in realizing solid-state cooling as an alternative to the conventional refrigeration with environmentally harmful coolant and low efficiency.High ECE in lead-free ferroelectric ceramics is highly desirable for the EC cooling.In this work,different from the researches that tune the ECE by conventional compositional design or external stress engineering,we fabricated the(1-x)BaTiO_(3)-xNaNbO_(3)(BTO-xNN)lead-free ceramics with a core-shell grain structure arising from the inhomogeneous stoichiometry of element distribution,leading to the internal compressing stress in the grains.It is interesting that the phase transition behavior,including the phase transition temperature and the diffusion property,is regulated by the core-shell grain structure induced internal stress,which can be capitalized on for the favorable ECE.Cooperated with 0.02 NN,a high ECE,e.g.adiabatic temperature change(ΔT)of 3.6 K and isothermal entropy change(ΔS)of 4.5 J kg^(-1) K^(-1),is attained in the BTO ceramic.As the internal stress further increases with more NN,the BTO-0.06NN exhibits an extremely stable ECE with a variety rate below ±4% in a wide temperature range from 300 K to 360 K.This work provides a novel approach to explore pronounced ECE in lead-free ferroelectrics for eco-friendly refrigeration.展开更多
基金supported by the National Science Foundation of China(Grant No.51972125,51772108,51972126 and 61675076)the Fund from Science,Technology and Innovation Commission of Shenzhen Municipality(JCYJ20180507182248925)+5 种基金the Innovation Fund of WNLO and the Fundamental Research Funds for the Central Universities(2019KFYRCPY126 and 2018KFYYXJJ052)the support from the Thousand Young Talent Program(Grant No.BE0200005)the support provided by the“Double First-Rate”Program(Grant No.WF220402017)the Prospective Research Program(Grant No.AF0200246)the Student Innovation Center at Shanghai Jiao Tong Universitysupported by the Key Research Program of Frontier Sciences,CAS(ZDBS-LY-JSC002).
文摘Electrocaloric effect(ECE)is promising in realizing solid-state cooling as an alternative to the conventional refrigeration with environmentally harmful coolant and low efficiency.High ECE in lead-free ferroelectric ceramics is highly desirable for the EC cooling.In this work,different from the researches that tune the ECE by conventional compositional design or external stress engineering,we fabricated the(1-x)BaTiO_(3)-xNaNbO_(3)(BTO-xNN)lead-free ceramics with a core-shell grain structure arising from the inhomogeneous stoichiometry of element distribution,leading to the internal compressing stress in the grains.It is interesting that the phase transition behavior,including the phase transition temperature and the diffusion property,is regulated by the core-shell grain structure induced internal stress,which can be capitalized on for the favorable ECE.Cooperated with 0.02 NN,a high ECE,e.g.adiabatic temperature change(ΔT)of 3.6 K and isothermal entropy change(ΔS)of 4.5 J kg^(-1) K^(-1),is attained in the BTO ceramic.As the internal stress further increases with more NN,the BTO-0.06NN exhibits an extremely stable ECE with a variety rate below ±4% in a wide temperature range from 300 K to 360 K.This work provides a novel approach to explore pronounced ECE in lead-free ferroelectrics for eco-friendly refrigeration.
