Temperature-induced phase transitions for stuffed tridymites SrGa2O4 and CaGa2O4

Stuffed tridymite γ-SrGa2O4 (P21/n) is the thermodynamically stable phase below 1200 °C, and it transforms to β-SrGa2O4 (P21/c) at 1200 °C. Similarly, the phase transition from α-CaGa2O4 (Pna21) to β-CaGa2O4 (P21/c) occurs at ~ 1350 °C. Rietveld refinements provide detailed structural information and suggest that the driving force of these phase transitions is the under-bonded nature of the alkaline earth cations.328