电热效应
材料科学
铁电性
薄膜
相变
凝聚态物理
钙钛矿(结构)
热电性
电介质
拉曼光谱
四方晶系
电场
介电常数
相(物质)
光电子学
纳米技术
结晶学
光学
化学
物理
有机化学
量子力学
作者
Yunlong Sun,Jianhao Du,Chenlu Jiang,Jun Liang,Xun Geng,Yu Wang,Danyang Wang
摘要
Electrocaloric effect (ECE) offers an efficient and environmentally friendly route for solid-state cooling. Either positive or negative ECE could exhibit a large adiabatic temperature change (ΔT). Compared to the positive electrocaloric response, the investigation of negative ECE is lagging behind, largely due to the fact that its origin is still elusive. In this work, the negative ECE behavior of conventional ferroelectric thin films, namely 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNBT), was studied. A remarkable ΔT of −26.1 K was acquired near 160 °C under a moderate electric field of 875 kV/cm, attributing to the ferroelectric phase transition in the polar nanoregions from rhombohedral (R3c) to tetragonal (P4bm), as confirmed by temperature-dependent dielectric permittivity, Raman spectra, and x-ray reciprocal space mapping. The BNBT thin film presents a high electrocaloric coefficient (ΔT/ΔE) of 0.0298 K cm kV−1, transcending that of the most reported negative electrocaloric response of thin films.
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