Phase transition and
compression behavior of gibbsite under high-pressure H. Liu1  , J. Hu2,
J. Xu2, Z. Liu2,
J. Shu2, H. K. Mao2 and
J. Chen3
| (1) |
HPCAT, Advanced Photon
Source, Argonne National Laboratory, IL,
60439–4803 |
| (2) |
Geophysical Laboratory,
Carnegie Institution of Washington, Washington, DC
20015 |
| (3) |
Mineral Physics Institute,
State University of New York, Stony Brook, NY
11794-2100 |
Received:
29 March 2003 Accepted:
26 January 2004
Abstract In situ
high-pressure synchrotron X-ray diffraction and infrared
absorption experiments for gibbsite were performed at room
temperature up to 53 and 25 GPa, respectively. A phase
transition was confirmed at about 2.5 GPa. The high-pressure
phase is indexed as an orthorhombic structure, rather than a
triclinic structure as reported in previous studies. The
compressibility of gibbsite and its high-pressure polymorph
were studied, and their bulk moduli K0 were
determined to be 49 and 75 GPa, respectively with
K0.gif) as 4. The in situ high-pressure
infrared absorption spectra revealed the gradual disordering
of hydrogen substructure above 15 GPa in quasihydrostatic
compression.
Keywords Al(OH)3 - High-pressure - Phase
transition - X-ray diffraction - Infrared
absorption
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