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Giant Negative and Positive Electrocaloric Effects Coexisting in Lead‐Free Na 0.5 Bi 4.5 Ti 4 O 15 Films Over a Broad Temperature Range
Author(s) -
Chen Jieyu,
Tang Zhehong,
Zhao Shifeng
Publication year - 2018
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201700443
Subject(s) - electrocaloric effect , ferroelectricity , materials science , electric field , dipole , perovskite (structure) , pyroelectricity , condensed matter physics , analytical chemistry (journal) , crystallography , dielectric , optoelectronics , chemistry , physics , organic chemistry , chromatography , quantum mechanics
Giant negative and positive electrocaloric effects (ECEs) coexist in lead‐free Na 0.5 Bi 4.5 Ti 4 O 15 (NBTO) ferroelectric films with layered perovskite structure over a broad temperature range, with Δ T peaks of −14.8 °C (at 273 K) in the negative electrocaloric (EC) region (273–328 K), of 3.45 °C (at 373 K) in the positive EC region (328–418 K) and of −6.76 °C (at 483 K) in another negative EC region (418–513 K), respectively, under the electric field of 900 kV cm −1 . Such giant ECEs are attributed to both the high break‐down electric field and prominent ferroelectricity. And the coexistence originates in the competition of the dipole polarization between both Na 0.5 Bi 0.5 TiO 3 (NBT) and Bi 4 Ti 3 O 12 (BTO) cells of NBTO films over the whole temperature region. Furthermore, the outstanding anti‐fatigue features with temperature stability for NBTO films ensure the durability of EC refrigeration. This work will prompt a novel technology for next generation of environmental‐friendly solid‐state cooling devices.