In Situ High-Pressure X-ray Diffraction Study of H2O Ice VII

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2813890· OSTI ID:959869

Somayazulu, M; Shu, J; Zha, C; Goncharov, A; Tschauner, O; Mao, H; Hemley, R

Ice VII was examined over the entire range of its pressure stability by a suite of x-ray diffraction techniques in order to understand a number of unexplained characteristics of its high-pressure behavior. Axial and radial polycrystalline (diamond anvil cell) x-ray diffraction measurements reveal a splitting of diffraction lines accompanied by changes in sample texture and elastic anisotropy. In situ laser heating of polycrystalline samples resulted in the sharpening of diffraction peaks due to release of nonhydrostatic stresses but did not remove the splitting. Radial diffraction measurements indicate changes in strength of the material at this pressure. Taken together, these observations provide evidence for a transition in ice VII near 14 GPa involving changes in the character of the proton order/disorder. The results are consistent with previous reports of changes in phase boundaries and equation of state at this pressure. The transition can be interpreted as ferroelastic with the appearance of spontaneous strain that vanishes at the hydrogen bond symmetrization transition near 60 GPa.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 959869
• Report Number(s): BNL--82855-2009-JA
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Vol. 128; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ANISOTROPY
DIFFRACTION
HEATING
HYDROGEN
ICE
LASERS
PROTONS
STABILITY
STRAINS
STRESSES
TEXTURE
X-RAY DIFFRACTION
national synchrotron light source