Structure, ferroelectric and piezoelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 modified BiFeO3–BaTiO3 lead-free piezoelectric ceramics
A new lead-free solid solution of (0.75 − x)BiFeO3–0.25BaTiO3–xBi0.5(Na0.8K0.2)0.5TiO3 + 1 mol% MnO2 has been prepared by a conventional ceramic technique and the effects of Bi0.5(Na0.8K0.2)0.5TiO3 and sintering temperature on the structure, ferroelectric and piezoelectric properties of the material have been studied. The ceramics sintered at 960 °C for 2 h possess a pure perovskite structure and no second phases can be detected. After the addition of Bi0.5(Na0.8K0.2)0.5TiO3, a morphotropic phase boundary of rhombohedral and orthorhombic phases is formed at x = 0.01. The addition of a small amount of Bi0.5(Na0.8K0.2)0.5TiO3 can promote the grain growth, while excess Bi0.5(Na0.8K0.2)0.5TiO3 causes an inhibition of grain growth. Sintering temperature has an important influence on the structure and electrical properties of the ceramics. The sintering temperature of 960 °C is a critical temperature to obtain the ceramics with good piezoelectric properties. For the ceramic with x = 0.01 sintered at/above 960 °C located at the morphotropic phase boundary, large grains, good densification, high resistivity and enhanced electrical properties are obtained.
KeywordsMnO2 BaTiO3 Sinter Temperature BiFeO3 Piezoelectric Property
This work was supported by the projects of Education Department of Sichuan Province (11ZA104), Science and Technology Bureau of Sichuan Province (2010JQ0046) and the Open Project of State Key Laboratory of Electronic Thin Films and Integrated Devices of University of Electronic Science and Technology of China (KFJJ201108).
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