Wiley, Journal of the American Ceramic Society, 4(98), p. 1372-1376, 2015
DOI: 10.1111/jace.13461
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The phase transition temperatures of CaZrO3-doped (Na0.49K0.49Li0.02)(Nb0.8Ta0.2)O3 lead-free piezoelectrics (LKNNT-CZ5) have been studied with X-ray diffraction and Raman scattering. It is found that LKNNT-CZ5 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.