Tetragonal–cubic phase transition in RbGaSi ₂ O ₆ synthetic leucite analogue

The leucite group structures are tetrahedrally coordinated silicate framework structures with some of the silicate framework cations partially replaced by divalent or trivalent cations. These structures have general formulae A 2 B Si 5 O 12 and AC Si 2 O 6 , where A is a monovalent alkali metal cation, B is a divalent cation, and C is a trivalent cation. These leucites can have crystal structures in several different space groups, dependent on stoichiometry, synthesis conditions, and temperature. Phase transitions are known for temperature changes. This paper reports a high-temperature X-ray powder diffraction study on RbGaSi 2 O 6, which shows a phase transition from I 4 1 /a tetragonal to Ia-3d bar on top of 3 cubic on heating from room temperature to 733 K. On cooling to room temperature, the crystal structure reverts to I 4 1 /a tetragonal.