Pressure-induced phase transition into the primitive orthorhombic lattice of synthetic lawsonite

Abstract

Lawsonite whose space group is Cmcm under ambient condition undergoes a phase transition into the primitive orthorhombic lattice around 4 GPa. To compare this pressure-induced phase transition with the low-temperature phase transition at 273 K, the space group of lawsonite under high-pressure was restricted by in-situ X-ray diffraction experiments on a single-crystal of synthetic lawsonite using a synchrotron radiation source. As a result, the space group was limited to Pmcn or P2₁cn. The structural refinement in the former shows the lower R-value.