TEMPERATURE DEPENDENCES OF PIEZOELECTRIC PROPERTIES OF TEXTURED (Bi_(1/2)K_(1/2))TiO_3-BaTi0_3 LEAD-FREE PIEZOELECTRIC CERAMICS

摘要

Temperature dependences of piezoelectric properties were investigated for (l-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_4Ti_3O_(12) particles as a template. The degree of orientation, F, which was determined by the Lotgering method using an X-ray diffraction pattern, achieved ≈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 pm/V (at 80 kV/cm), respectively. From the temperature dependences of piezoelectric properties, a depolarized temperature, T_d, was about 275°C and the d_(33) indicated approximately 278 pC/N at 250°C.