TY - JOUR
T1 - Space group and hydrogen sites of δ-AlOOH and implications for a hypothetical high-pressure form of Mg(OH)2
AU - Kudoh, Y.
AU - Kuribayashi, T.
AU - Suzuki, A.
AU - Ohtani, E.
AU - Kamada, T.
PY - 2004/7
Y1 - 2004/7
N2 - The space group and hydrogen positions of δ-(Al0.84 Mg0.07Si0.09)OOH are investigated using a single crystal synthesized using a multi-anvil apparatus under conditions of 1000 °C and 21 GPa. The space group determined by single-crystal X-ray diffraction is to Pnn 2, with unit-cell parameters of a = 4.6975(8) Å, b = 4.2060(6) Å, c = 2.8327(4) Å, and V = 55.97(1) Å3. Partial occupancy of the Al site by Mg and Si suggests the possibility of a limited solid solution between δ-AlOOH, stishovite, and a hypothetical CaCl2-type Mg(OH)2 that is 16% denser than brucite. Difference-Fourier maps reveal two small but significant Fourier peaks attributable to hydrogen atoms. Atomic distances and angles around the first peak indicate a hydrogen bond with O⋯O distances of 2.511 Å, while those around the second peak are suggestive of a bifurcated hydrogen bond with O⋯O distances of 2.743 and 2.743 Å.
AB - The space group and hydrogen positions of δ-(Al0.84 Mg0.07Si0.09)OOH are investigated using a single crystal synthesized using a multi-anvil apparatus under conditions of 1000 °C and 21 GPa. The space group determined by single-crystal X-ray diffraction is to Pnn 2, with unit-cell parameters of a = 4.6975(8) Å, b = 4.2060(6) Å, c = 2.8327(4) Å, and V = 55.97(1) Å3. Partial occupancy of the Al site by Mg and Si suggests the possibility of a limited solid solution between δ-AlOOH, stishovite, and a hypothetical CaCl2-type Mg(OH)2 that is 16% denser than brucite. Difference-Fourier maps reveal two small but significant Fourier peaks attributable to hydrogen atoms. Atomic distances and angles around the first peak indicate a hydrogen bond with O⋯O distances of 2.511 Å, while those around the second peak are suggestive of a bifurcated hydrogen bond with O⋯O distances of 2.743 and 2.743 Å.
KW - High-pressure form of Mg(OH)
KW - Hydrogen sites
KW - Space group
KW - δ-AlOOH
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U2 - 10.1007/s00269-004-0404-0
DO - 10.1007/s00269-004-0404-0
M3 - Article
AN - SCOPUS:20444477547
SN - 0342-1791
VL - 31
SP - 360
EP - 364
JO - Physics and Chemistry of Minerals
JF - Physics and Chemistry of Minerals
IS - 6
ER -