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- Title
Raman spectroscopy of hot hydrogen above 200 GPa.
- Authors
Howie, Ross T.; Dalladay-Simpson, Philip; Gregoryanz, Eugene
- Abstract
It has been theorized that at high pressure the increased energy of the zero-point oscillations in hydrogen would destabilize the lattice and form a ground fluid state at 0 K (ref. ). Theory has also suggested that this fluid state, representing a new state of matter, might have unusual properties governed by quantum effects, such as superfluidity or superconductivity. Here, by combining Raman spectroscopy and in situ high-temperature, high-pressure techniques, we demonstrate that above 200 GPa a new phase transition occurs as temperature is increased, for example 480 K at 255 GPa. If the transformation is interpreted as melting, it would be the lowest melting temperature of any material at these high pressures. We also find a new triple point between phases I and IV and the new phase, and demonstrate that hydrogen retains its molecular character around this point. These data may require a significant revision of the phase diagram of hydrogen above 200 GPa.
- Subjects
HYDROGEN spectra; RAMAN spectroscopy; SUPERCONDUCTIVITY; SUPERFLUIDITY; QUANTUM theory; MELTING; PHASE diagrams
- Publication
Nature Materials, 2015, Vol 14, Issue 5, p495
- ISSN
1476-1122
- Publication type
Article
- DOI
10.1038/nmat4213