Dielectric, piezoelectric and pyroelectric properties of (BiNa)_1/2TiO_3- based ceramics

Abstract

A bismuth sodium titanate, (BiNa)_1/2 TiO₃ (BNT)-based solid solutions, (1−x) (BiNa)_1/2TiO₃ + x(a·SrTi0₃ +b·PbTiO₃ +c·CaTiO₃) (a + b + c = l), (BNTX [100x-100a/100b/100c]), were studied for their dielectric, piezoelectric and pyroelectric properties. X-ray diffraction data show that a rhombohedra1 (Fα-tetragonal (Fβ) phase boundary (MPB) exists at x = 0.13 for a = b = 0.5 and c = 0, for a = 0 and b = c = 0.5, or for a = 0, b = 0.75 and c = 0.25, respectively. (Sr/Pb/Ca)-modified BNTs (BNTX [13-50/50/0], [13-0/50/50] and [13-0/75/25]) ceramics are superior for piezoceramics, with a lower free permittivity, ε^T3₃/ε₀ (≌240–430) and a high electromechanical coupling factor, k_t or k₃₃ (≌50%). along with a higher frequency constant, N, (≌ 3200 Hz.m). Figures of merit for pyrosensor materials of the BNTX [10-50/50/0] are comparable to those of PZT or PbTi0₃-based ceramics.