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Metallic Hydrogen:
Metallic hydrogen was first created - at Livermore in 1996 - in the liquid state at relatively high temperature. Whether solid metallic hydrogen can be created, however, remains unclear so far. According to early calculations, solid hydrogen should start conducting at about 340 GPa. The compression of solid hydrogen to 342 GPa at Cornell University in 1998 failed to produce the metallic phase, however. Now experiments by P Loubeyre and colleagues in France may help develop a more accurate theoretical model and identify conditions necessary for solid metallic hydrogen to form. The team used Raman spectroscopy to obtain a detailed absorption spectrum of solid hydrogen at pressures up to 320 GPa. It is found that as pressure increases from 290 GPA to 320 GPa, the sample changes its color from white through yellow and red to black. Of particular importance is the discovery at a pressure above 300 GPa of an energy gap characteristic of semiconductors. As pressure is increased to 320 GPa, the gap narrows. Extrapolation shows that at 450 GPa the gap should disappear, turning solid hydrogen to a (metallic) conductor.
Reference:
http://www.nature.com
Metallic hydrogen was first created - at Livermore in 1996 - in the liquid state at relatively high temperature. Whether solid metallic hydrogen can be created, however, remains unclear so far. According to early calculations, solid hydrogen should start conducting at about 340 GPa. The compression of solid hydrogen to 342 GPa at Cornell University in 1998 failed to produce the metallic phase, however. Now experiments by P Loubeyre and colleagues in France may help develop a more accurate theoretical model and identify conditions necessary for solid metallic hydrogen to form. The team used Raman spectroscopy to obtain a detailed absorption spectrum of solid hydrogen at pressures up to 320 GPa. It is found that as pressure increases from 290 GPA to 320 GPa, the sample changes its color from white through yellow and red to black. Of particular importance is the discovery at a pressure above 300 GPa of an energy gap characteristic of semiconductors. As pressure is increased to 320 GPa, the gap narrows. Extrapolation shows that at 450 GPa the gap should disappear, turning solid hydrogen to a (metallic) conductor.
Reference:
http://www.nature.com