TEMPERATURE DEPENDENCES OF PIEZOELECTRIC PROPERTIES OF TEXTURED (Bi1/2K1/2)TiO3-BaTiO3 LEAD-FREE PIEZOELECTRIC CERAMICS

Temperature dependences of piezoelectric properties were investigated for (1-x) (Bi(1/2)K(1/2))TiO(3)-xBaTiO(3) [abbreviated to BKT-BT100x] ceramics prepared by a reactive templated grain growth (RTGG) method using platelike Bi(4)Ti(3)O(12) particles as a template. The degree of orientation, F, which was determined by the Lotgering method using an X-ray diffraction pattern, achieved approximate to 83% in the textured BKT-BT10 ceramic. Textured BKT-BT10 ceramic with a homogeneous microstructure was obtained by the longer sintering time of 100 h. The field-induced strains and piezoelectric properties of the BKT-BT10 ceramic were improved by the grain orientation. In particular, the piezoelectric strain constant, d(33), and the normalized strain, d(33), of the textured BKT-BT10 ceramic in a direction parallel (//) to the tape stacking direction were 121 pC/N and 211 pmN (at 80 kV/cm), respectively. From the temperature dependences of piezoelectric properties, a depolarized temperature, T(d), was about 275 degrees C and the d(33) indicated approximately 278 pC/N at 250 degrees C.