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Negative piezoelectric behaviors in hybrid improper ferroelectric Ca 3‐ x Na x Ti 2 O 7 ( x = 0, 0.01) ceramics
Author(s) -
Jiang Yao,
Wang Shouyu,
Lei Yunlin,
Zhang Xiongnan,
Liu Weifang
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17145
Subject(s) - piezoelectricity , ferroelectricity , materials science , van der waals force , coercivity , piezoelectric coefficient , condensed matter physics , ceramic , crystal structure , piezoresponse force microscopy , polarization (electrochemistry) , analytical chemistry (journal) , mineralogy , crystallography , composite material , dielectric , chemistry , optoelectronics , physics , organic chemistry , chromatography , molecule
Hybrid improper ferroelectric Ca 3 Ti 2 O 7 (CTO) and Ca 2.99 Na 0.01 Ti 2 O 7 (NaCTO) ceramics were synthesized using the solid‐state reaction method. X‐ray powder diffraction technique was used to determine the phase purity and crystal structure of the prepared ceramics. We investigated their ferroelectric polarization, dynamic switching current, and piezoelectric properties, and confirmed their ferroelectric reversal property with a coercive field of 60‐80 kV/cm. A negative piezoelectric behavior was observed with a maximum strain of −0.01% and −0.007% for CTO and NaCTO, respectively. This abnormal piezoelectric behavior can be used to prepare composites with conventional oxide materials that generally exhibit positive piezoelectricity. Mechanism of the negative piezoelectricity effect was ascribed to its special quasi‐two‐dimensional (quasi‐2D) crystal structure with weak van der Waals (vdW) layers alternating with covalent layers.