Piezoelectric properties in (K0.5Bi0.5)TiO 3-(Na0.5Bi0.5)TiO3-BaTiO 3 lead-free ceramics |
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Authors: | Shujun Zhang Shrout TR Nagata H Hiruma Y Takenaka T |
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Affiliation: | Mater. Res. Inst., Pennsylvania State Univ., University Park, PA; |
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Abstract: | Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO 3-y(K0.5Bi0.5)TiO3-zBaTiO 3 x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280degC and 262degC were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5 Bi0.5)TiO3-0.07BaTiO$ d3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K 0.5Bi0.5)TiO3-0.04BaTiO$ d3 (BNBK88), with depolarization temperatures of 224degC and 162degC, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (~40 muC/cm2) was larger than that of BNBK79 (~29 muC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed |
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