Shock‐induced phase transition of MnO around 90GPa

Abstract

Shock compression experiments on single crystal MnO grown by the Verneuil method have been carried out for the pressure range of 41–114GPa using both propellant and two‐stage light‐gas guns. The shock states, recorded with the inclined mirror method, were analyzed by the free‐surface approximation and impedance‐match solution. The observed shock compression curve of MnO with the rock salt structure(B1) is found to be slightly more compressible than that measured statically to 60GPa using a diamond‐anvil cell. We observed a phase transition around 90GPa with a volume decrease of approximately 8%. The present phase transition pressure falls on a trend of B1‐B2(CsCl‐type structure) transformation among alkaline earth metal monoxides, rather than transformation to the B8(NiAs‐type structure) that wüstite (FeO) demonstrates.