HR: 0800h
AN: MR41A-0913 [Abstracts]
TI: Hydrogen Bonding Behavior Prior to Dehydroxylation: An In-Situ High-Temperature Neutron Diffraction
Study of Deuterated Brucite
AU: * Xu, H
EM: hxu@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AU: Zhao, Y
EM: yzhao@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AU: Hickmott, D
EM: dhickmott@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AU: Zhang, J
EM: jzhang@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AU: Daemen, L
EM: lld@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AU: Vogel, S
EM: sven@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Neutron Science Center and Earth and Environmental Sciences
Division, MS H805, Los Alamos, NM 87545
United States
AB:
The structure of deuterated brucite, Mg(OD)2, has been investigated using time-of-flight neutron diffraction in the
temperature range 313-553 K. Rietveld analysis of the obtained data reveals that with increasing temperature, the amplitude
of thermal vibration for D increases linearly from 313 to 493 K but then exponentially up to 553 K, immediately prior to the
brucite dehydroxylation. From 493 to 553 K, the interatomic interaction of D with the O and D associated with the adjacent
[MgO6] layer becomes drastically weakened, whereas the O-D bond is strengthened, as manifested by the rapid increase in
the D···O and D···D distances and the decrease in O-D. These exponential trends are in
striking contrast with the nearly linear variations in cell parameters with temperature throughout the temperature range
313-553 K. The behavior of cell dimensions, particularly along c, can be interpreted as a net result of contraction
in the thickness of the [MgO6] layer and expansion in the interlayer distance with increasing temperature.
DE: 1012 Reactions and phase equilibria (3612, 8412)
DE: 3620 Mineral and crystal chemistry (1042)
DE: 3949 Thermal expansivity
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 3994 Instruments and techniques
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005