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Effects of Bi 0.5 Na 0.5 HfO 3 addition on the phase structure and piezoelectric properties of (K, Na)NbO 3 ‐based ceramics
Author(s) -
Chen Yi,
Xue Dandan,
Shi Meng,
Jiang Xianquan,
Chen Zhiqian,
Liu Xiaokui,
Liu Gang,
Xu Zunping
Publication year - 2017
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.14916
Subject(s) - phase boundary , materials science , orthorhombic crystal system , tetragonal crystal system , curie temperature , piezoelectricity , dielectric , microstructure , ceramic , analytical chemistry (journal) , phase (matter) , mineralogy , phase transition , crystal structure , crystallography , condensed matter physics , composite material , chemistry , optoelectronics , organic chemistry , chromatography , physics , ferromagnetism
Abstract Lead‐free perovskite (1‐ x )(K 0.48 Na 0.48 Li 0.04 )Nb 0.95 Sb 0.05 O 3 ‐ x (Bi 0.5 Na 0.5 )HfO 3 piezoelectric ceramics were prepared by a traditional ceramic fabrication method. An investigation was conducted to assess the effects of (Bi 0.5 Na 0.5 )HfO 3 content on the crystal structure, microstructure, phase‐transition temperatures, and piezoelectric properties of the ceramics. The X‐ray diffraction results, combined with the temperature dependence of dielectric properties, revealed that the ceramics experienced a structural transition from an orthorhombic phase to a tetragonal phase with the addition of (Bi 0.5 Na 0.5 )HfO 3 , and a coexistence of orthorhombic and tetragonal phases was identified in the composition range of 0.005≤ x ≤0.015. An obviously improved piezoelectric activity was obtained for the ceramics with compositions near the orthorhombic‐tetragonal phase boundary, among which the composition x =0.005 exhibited the maximum values of piezoelectric constant d 33 , and planar and thickness electromechanical coupling coefficients ( k p and k t ) of 246 pC/N, 0.435, and 0.554, respectively. Furthermore, the Curie temperature of the ceramics was found decreasing with the increase in (Bi 0.5 Na 0.5 )HfO 3 content, but still maintaining above 300°C for the phase boundary compositions. These results indicate that the ceramics are promising lead‐free candidate materials for piezoelectric applications.