Figure 1

Thermodynamical stability of new yttrium hydrides at high pressure.
Formation enthalpies (ΔH) of various Y-H stoichiometries with respect to (Y + solid H2, a) and (YH3 + solid H2, b) at 100, 140 and 160 GPa. ΔH in (a) and (b) were calculated with equations of ΔH = HYHn – (HY + nHH2/2) and ΔH = HYHn – (HYH3 + (n-3)HH2/2, respectively. (c) and (d) present the static enthalpy curves of various structures of YH4 and YH6 relative to (YH3 + solid H2) as functions of pressure without (main figures) and with (insets) zero-point energy corrections, respectively.