A High Temperature X-Ray Diffraction Investigation of the β-(Bi2O3)1-x(SrO)x Solid Solution

AbstractThe incidence of phase transitions in the β-(Bi2O3)1-x(SrO)x solid solution was examined over the composition range x = 0.18–0.42 using in situ high temperature X-ray diffraction. The a lattice parameter of the rhombohedral structure (referenced to hexagonal axes) is approximately constant across the entire composition range of the β-phase. The c parameter also remains approximately constant at compositions of x ≤ 0.28, but at x > 0.28 this parameter shows a marked increase in compositional dependence. The temperature dependence of the a and c lattice parameters exhibits discrete discontinuities at distinct temperatures T0 which occur between 600 and 710 °C depending on the composition. These fully reversible effects confirm previous reports of structural discontinuities, and are consistent with observations of enhanced ionic conductivity, differential thermal analysis (DTA) peaks and transmission electron microscope (TEM) superlattice reflections indicative of an order:disorder transition in the ...