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Melting behavior of H 2 O at high pressures and temperatures
Author(s) -
Lin JungFu,
Gregoryanz Eugene,
Struzhkin Viktor V.,
Somayazulu Maddury,
Mao Hokwang,
Hemley Russell J.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022499
Subject(s) - melting curve analysis , triple point , uranus , mantle (geology) , melting point , geothermal gradient , neptune , diamond anvil cell , synchrotron , raman spectroscopy , geology , silicate , thermodynamics , materials science , planet , mineralogy , high pressure , physics , chemistry , geophysics , astrophysics , optics , polymerase chain reaction , biochemistry , astronomy , composite material , gene
Water plays an important role in the physics and chemistry of planetary interiors. In situ high pressure‐temperature Raman spectroscopy and synchrotron x‐ray diffraction have been used to examine the phase diagram of H 2 O. A discontinuous change in the melting curve of H 2 O is observed at approximately 35 GPa and 1040 K, indicating a triple point on the melting line. The melting curve of H 2 O increases significantly above the triple point and may intersect the isentropes of Neptune and Uranus. Solid ice could therefore form in stratified layers at depth within these icy planets. The extrapolated melting curve may also intersect with the geotherm of Earth's lower mantle above 60 GPa. The presence of solid H 2 O would result in a jump in the viscosity of the mid‐lower mantle and provides an additional explanation for the observed higher viscosity of the mid‐lower mantle.