Two high pressure phases were synthesised by static compression, the first with a CaCl 2 structure, and the second with a modified fluorite structure which seemed to possess a very high hardness. In this study, shock compression recovery experiments were performed to synthesise these phases using a powder gun. The first high pressure phase was successfully produced as a single phase by mixing ruthenium oxide with copper. We did not succeed in reaching the cubic phase, probably because either the pressure was not high enough or the time duration was too short.