Fig. 6
From: Synthesis of clathrate cerium superhydride CeH9 at 80-100 GPa with atomic hydrogen sublattice
Effect of hydrogen on unit cell volume and nearest neighbour distances in various hydrides at different pressures. a Experimentally obtained volume per formula unit for CeH3 and CeH9 plotted as a function of pressure. Blue open squares and red solid tringles represent experimental data for CeH3 and CeH9 respectively. Errors in the fitting are also plotted. Theoretical EOS of CeH3 and CeH9 is plotted as blue and red lines, respectively. Black dashed line represents EOS of cerium metal68. Red, purple and green dashed curves represent ideal mixtures of Ce+(9/2)H2, Ce+(8/2)H2, and Ce+(7/2)H2, respectively68,71. b Volume expansion (ΔVH) per hydrogen atom plotted against pressure for CeH9, FeH531, H3S14, LaH1032, H71, and atomic H31 for comparison. Dark yellow, purple, black, and orange open triangle symbol-line represents H3S, LaH10, atomic H, and FeH5, respectively. Red solid triangle symbols represent CeH9. Black solid line represents hydrogen. c Comparison of the pressure dependence of the nearest H–H distances for CeH9, FeH341, FeH531, AlH342, H3S14, LaH1032, and atomic H31. Magenta, blue, dark yellow, orange, purple, and black open triangle symbol line represents FeH3, AlH3, H3S, FeH5, LaH10, and atomic H, respectively. Red solid triangle symbol line represents CeH9. d Nearest Ce–H distance for CeH9 as a function of pressure. Inset shows CeH29 clathrate cage in P63/mmc structure. [Pressure-dependent experimental data is at 300 K, whereas theoretical data is at 0 K]
