High temperature X-ray single crystal study of Na_1/2Bi_1/2TiO₃

Abstract

Abstract For a Na0.5B0.5TiO2 single crystal the intensity variation of the satellite reflection was measured by X-ray diffraction. No hystereses were observed for the phase transitions into both the rhombohedra1 and the tetragonal phases, however there is a coexistence of both phases in the range between ∼250°C and 300°C. By fitting the intensity vs. temperature curve for the tetragonal phase a critical exponent of 2β = 0.39(4) was obtained. The mean square displacement of the probability tensor of the high temperature cubic phase does not vary linearly with temperature which indicates that there is some disorder in this phase. Key Words: Na1/2Bi1/2TiO3 Phase transitions