High temperature piezoelectric materials for actuators and sensors

(1-x)BiScO3-xPbTiO(3) (BSPT) polycrystalline material with a morphotropic phase boundary (MPB) composition (x=0.64) exhibits a high Curie temperature (T-C) about 450 degrees C and good piezoelectric properties with d(33) values around 460pC/N. Manganese (Mn) modified BSPT was utilized in order to increase the electric resistivity and RC time constant. At 450 degrees C, BSPT66-Mn ceramic exhibited a resistivity of 3x10(7) Ohm.cm and RC value of 0.08s, respectively, significantly higher than the values for undoped BSPT and commercial PZT5 materials. The manganese additive shifts T-C of BSPT materials to lower temperatures, which were found to be 442 degrees C and 462 degrees C for modified BSPT64 and BSPT66, respectively. The piezoelectric behavior for the modified BSPT material was found to deteriorate slightly owing to the hardening effect of manganese, but showed superior temperature stability and enhanced resistivity. The detailed temperature dependent properties were studied in this work and compared to commercial PZT5 materials. The complete set of materials constants, including the elastic s(ij), c(ij), piezoelectric d(ij), e(ij), g(ij), h(ij), dielectric e(ij), beta(ij) and electromechanical k(ij) values were determined using resonance technique and derived from the experimental data.