Lead-free Na0.5K0.5NbO3 piezoelectric ceramics fabricated by spark plasma sintering: Annealing effect on electrical properties
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Niobate ceramics such as NaNbO3 and KNbO3 have been studied as promising Pb-free piezoelectric ceramics, but their sintering densification is fairly difficult. In the present study, highly dense Na0.5K0.5NbO3 ceramics with submicron grains were prepared using SPS, whose density was raised to 4.47 g/cm3 (>99% of the theoretical density) at 920 °C. Reasonably good ferroelectric and piezoelectric properties were obtained in the SPSed Na0.5K0.5NbO3 ceramics after annealing in air. The effect of annealing time on the electrical properties was investigated to determine optimal processing condition. The piezoelectric parameter (d 33) of the Na0.5K0.5NbO3 ceramics annealed properly reached 148 pC/N.
KeywordsLead-free piezoelectric ceramic Spark plasma sintering Na0.5K0.5NbO3
The authors wish to thank Toyota Motor Corporation for their support to Tsinghua-Toyota collaborative research on lead-free piezoelectric ceramics. This work was also partly supported by the National Natural Science Foundation of China (Grant No. 50325207) and the Ministry of Science and Technology (Grant No. 2002CB613306).
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