Effect of Bi_2O_3 addition and sintering time on the physical and electrical properties of lead-free (Na_<0.5>Bi_<0.5>)TiO_3-Ba(Zr_<0.04>Ti_<0.96>)O_3 ceramics

概要

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Although PbZrO3-PbTiO3 (PZT)-based ceramics are playing a dominant role in piezoelectric materials, their evaporation of harmful lead oxide during the sintering process causes a crucial environment problem. It is necessary to search for lead-free piezoelectric materials that have such excellent properties as those found in the PZT-based ceramics. Therefore (Na0.5Bi0.5)TiO3-based solid solutions were studied to improve piezoelectric properties. In the present study, various quantities of Bi2O3 were added into 0.99(Na0.5Bi0.5)TiO3-0.01Ba(Zr0.04Ti0.96)O3 (0.99NBT-0.01BZT) ceramics. High-density samples were obtained through the addition of Bi2O3 into 0.99NBT-0.01BZT ceramic. It was found that 0.99NBT-0.01BZT with the addition of 0-4.0 wt% Bi2O3 exhibit relatively good piezoelectric properties. For 0.99NBT-0.01BZT ceramic with the addition of 0.5 wt% Bi2O3, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.15 and 0.55, respectively, at the sintering of 1100°C for 2 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.6. It is obvious that 0.99NBT-0.01BZT solid solution ceramic by adding low quantities of Bi2O3 is one of the promising lead-free ceramics for high frequency electromechanical transducer applications.
公益社団法人日本セラミックス協会の論文
2009-05-01