High Temperature "Hard" Piezoelectric Ceramics of BiScO3-PbTiO3-Pb(Nb, EMn)O3 with Fe2O3 Addition

"Hard" piezoelectric materials of Fe modified 0.37BiScO(3)-0.6PbTiO3-0.03Pb(Mn1/3Nb2/3)O-3 (BS-PT-PMN-Fe) ceramics were prepared by traditional solid state reaction method. X-ray diffraction (XRD) analysis revealed that BS-PT-PMN-Fe ceramics showed single perovskite structure with dominant tetragonal phase, and the c/a ratios was enlarged with Fe content. The grain size of BS-PT-PMN-Fe ceramics decreased obviously from 25 to 1 mu m with the increase of Fe content from 0 to 3 mol%. The dielectric and piezoelectric properties of BS-PT-PMN-Fe ceramics with 2 mol% Fe addition are as follows: epsilon = 600, tan delta = 0.008, d(33) = 240, Q(m) = 500, and k(p) = 0.38, which were comparable to those of PZT-4 traditional "hard" piezoelectric ceramics. Both piezoelectric and dielectric properties were stable from room temperature up to 400 degrees C, about 250 degrees C higher than those of conventional PZT piezoelectric ceramics. In addition, the temperature coefficient of resonance frequency (TCF) of ceramics with 3 mol% Fe addition was -21 ppm/degrees C, which is one tenth that of PZT ceramics.