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Intergranular Stress Induced Phase Transition in CaZrO 3 Modified KNN‐Based Lead‐Free Piezoelectrics
Author(s) -
Chen Feng,
Li YuanHang,
Gao GuanYin,
Yao FangZhou,
Wang Ke,
Li JingFeng,
Li XiaoLong,
Gao XingYu,
Wu Wenbin
Publication year - 2015
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.13461
Subject(s) - materials science , tetragonal crystal system , orthorhombic crystal system , phase transition , crystallite , phase (matter) , raman spectroscopy , crystallography , analytical chemistry (journal) , mineralogy , crystal structure , condensed matter physics , metallurgy , chemistry , physics , organic chemistry , chromatography , optics
The phase transition temperatures of CaZrO 3 ‐doped (Na 0.49 K 0.49 Li 0.02 )(Nb 0.8 Ta 0.2 )O 3 lead‐free piezoelectrics ( LKNNT ‐ CZ 5) have been studied with X‐ray diffraction and Raman scattering. It is found that LKNNT ‐ CZ 5 ceramics and powders with the same crystallite size (~2–5 μm) exhibit distinctly different phase transition behaviors versus temperature. The ceramic bulk changes its orthorhombic phase to tetragonal structure abruptly after being pulverized to powders at room temperature( RT ), and follows a phase transition sequence with increasing temperature: orthorhombic ( RT –65°C), orthorhombic and tetragonal (65°C–105°C), and tetragonal phase (105°C to ~220°C). Contrastively, the powders hold a tetragonal structure without any phase transition within the whole temperature region ( RT –220°C). These differences might be induced by the existing internal stress or residual strain, which could be released during the grinding process.