The variation of phase transition behavior on substituting Pb²⁺ and Sr²⁺ for a site cations in (Na_1/2Bi_1/2)TiO₃ system

Abstract

The phase transition behavior in (Na_1/2Bi_1/2)_1-xPb_xTiO₃[NBPT(x)] and (Na_1/2Bi_1/2)_1-xSr_xTiO₃[NBST(x)] with respect to changes in composition and temperature was investigated using X-ray analysis and dielectric characterization. Morphotropic phase boundary(MPB) are located in the composition range of 0.13 < × < 0.15 and 0.25 < × < 0.26 in NBPT(x) and NBST(x), respectively. The phase transition exhibited more 1st order behavior and the dielectric loss could be suppressed at high temperatures with the increase of Pb²⁺ substitutions. NBST(x) showed diffuse phase transition and the degree of the shift in permittivity peak with the measuring frequency increased with the increase of SrTiO₃ content. This increase was correlated with the symmetry at room temperature and decrease of the temperature of maximum permittivity