Crystal Growth and Electrical Properties of Lead-Free Piezoelectric Material (Na_1/2Bi_1/2)TiO₃–BaTiO₃

Abstract

Single crystals of lead-free piezoelectric material x (Na 1/2 Bi 1/2 )TiO 3 – y BaTiO 3 (NBBT 100 x /100 y ) have been successfully grown by the flux method and the Bridgman method. Using the flux method, crystals having an edge length of 2–8 mm were obtained using Bi 2 O 3 flux with cooling from 1350°C to 800°C at a rate of 3.5°C/h. Using the Bridgman method, comparatively good crystal of 15 mm diameter and 50 mm length was obtained using Bi 2 O 3 flux with the Pt crucible driven down through the heat zone at a speed of 1.0 mm/h. The resulting crystals showed single-phase perovskite structure. Inductively charged plasma (ICP) chemical analysis revealed that the composition of the pulverized powder of these crystals is NBBT 97/3, which is slightly different from the charged composition of NBBT 94/6. One of the single crystals grown by the Bridgman method showed a dielectric constant of 1230 at room temperature and a dielectric constant peak at 313°C.