Investigation of orthorhombic–tetragonal structural crossover in (Ba_0.92Ca_0.08)(Zr_0.05Ti_0.95)O₃

The orthorhombic to tetragonal phase transition in (Ba_0.92Ca_0.08)(Zr_0.05Ti_0.95)O₃ was investigated using high-temperature X-ray diffraction between 260 and 333 K. The results established the presence of tetragonal (P4mm) and orthorhombic (Amm2) phase co-existence in the temperature range of 293 ≤ T ≤ 313 K. The tetragonal phase was found to increase from 27% at 293 K to 76% at 313 K. The structural refinement and line-profile analysis ruled out the presence of an intermediate monoclinic structure during P4mm → Amm2 crossover. The analysis shows a pure orthorhombic (Amm2) structure for T < 293 K and tetragonal for T > 313 K.