Fig. 3
From: Synthesis of clathrate cerium superhydride CeH9 at 80-100 GPa with atomic hydrogen sublattice
Pressure temperature path for the synthesis and stability of various Ce–H phases. a Starting at 9 GPa, cerium reacts with hydrogen to form \(Fm\bar 3m\mbox {-}{\mathrm{CeH}}_{\mathrm{2}}\), which remained stable up to 33 GPa. b At 33 GPa with laser heating, \(Fm\bar 3m\mbox {-}{\mathrm{CeH}}_{\mathrm{2}}\) in H2 medium reacted to form \(\beta \mbox {-}Pm\bar 3n\mbox {-}{\mathrm{CeH}}_{\mathrm{3}}\). \(\beta \mbox {-}Pm\bar 3n\mbox {-}{\mathrm{CeH}}_{\mathrm{3}}\) remained stable up to 80 GPa. c Laser heating of \(\beta \mbox {-}Pm\bar 3n\mbox {-}{\mathrm{CeH}}_{\mathrm{3}}\) in H2 medium at 80-100 GPa resulted in the occurrence of the P63/mmc-CeH9 superhydride. The superhydride phase was found to be stable up to the maximum pressure reached in our studies i.e. 100 GPa. d After complete decompression, \(\beta \mbox {-}Pm\bar 3n \mbox{-}{\mathrm{CeH}}_{\mathrm{3}}\) and \(I4_1md\mbox {-}{\mathrm{Ce}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{5}}\) were recovered at ambient conditions
