hR9 and hR18 unit cells) at ambient pressure, under high pressure (>12 GPa/120 kbar) this phase has been observed exhibit superconducting transition.
Cells of the hR9 and hR18 type have been studied at standard pressure conditions, but under extreme pressures (in excess of 12 GPa/120 kbar), this phase is found to undergo a superconducting transformation.