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Author(s): |
Lu Li, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan, China
Yue-qiu Gong, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan, China
Lun-jun Gong, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan, China
Hui Dong, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan, China |
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Abstract: |
A series of lead-free piezoelectric K0.5Na0.5Nb1–xTaxO3 (hereafter, abbreviated as KNNTx) (x?0?0.4) powders were prepared successfully by solvothermal method at relatively low temperature (180℃). The corresponding ceramics were obtained using conventional solid-solution method. X-ray diffractions and scanning electron microscopy observations show that a well homogeneous and single-phase solid solution with perovskite structure over the whole composition is formed. The grain size is about 1?5μm. After investigating density, microstructure and electric properties of these ceramics, we found that the optimum sintering temperature of these samples is in the range of 960?980℃. In addition, the tantalum (Ta) contents have an obvious relation with the best poling temperature (Tp). With the increasing of Ta content, the optimum Tp shifts toward lower temperature. This result is considered to be closely related to the phase temperature of orthorhombic and tetragon (TO-T). The piezoelectric constant d33 and planar mode electromechanical coupling coefficient Kp of KNNT0.3 ceramics showed maximum values of 156 pC/N and 0.32, respectively. These materials have potential application values in micro-sensor, actuator and acoustic surface wave devices.
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