Solid Hydrogen at Ultra High Pressure

摘要: In recent years the diamond anvil cell (DAC) technique has been developed to statically compress matter, with pressures reaching into hundreds of gigapascals (100 GPa = 1 megabar). One most interesting substances study under these conditions is solid hydrogen, which predicted have a number phase transitions, including insulator-metal (IM) transition. At very high order 300–400 GPa, hydrogen become metallic atomic (Wigner and Huntington, 1935; Ceperley Alder, 1987). However, it expected that first becomes metal at somewhat lower pressures, within molecular phase, by an electronic band overlap mechanism (Ramaker et al., 1975; Friedli Ashcroft, 1977). Phase transitions in studied methods, Raman scattering optical reflection absorption. An unexpected new shown exist for above 149 pressure-temperature line (Lorenzana, Silvera, Goettel, 1989). This called hydrogen-A (H-A) suspected, on grounds H-A metallic. this time there no direct evidence support interpretation. On theoretical side calculations gap closure, or metallization, pressure 150–180 structure hcp lattice molecules oriented along c-axis (Garcia 1990). Again, uncertainties arise, as find different energy larger metallization pressure. article I shall discuss rapid developments challenging area research.