Title: Crystal structure of CaMg<sub>2</sub>Al<sub>6</sub>O<sub>12</sub>, a new Al-rich high pressure form
Abstract:The crystal structure of CaMg2Al6O12, a new high-pressure phase synthesized at 21.8 GPa and 1200 °C using a multi-anvil apparatus, was solved by a newly developed structure program and refined by Riet...The crystal structure of CaMg2Al6O12, a new high-pressure phase synthesized at 21.8 GPa and 1200 °C using a multi-anvil apparatus, was solved by a newly developed structure program and refined by Rietveld analysis of the powder X-ray diffraction profile. The structure is hexagonal with cell constants a = 8.7616(2) and c = 2.7850(1) Å, and space group P63/m. The structure of this phase contains double chains of edge shared AlO6 octahedra running along the c axis. Three double chains share corners to form sixfold positions in which octahedrally coordinated Mg atoms reside. The large Ca atoms are randomly distributed at ninefold sites with half-occupancy in the hexagonal tunnel. Previously reported Al-rich silicate phases could possibly have the same structure. This structure could thus qualify as one of the possible major host phases for aluminum in the lower mantleRead More
Publication Year: 2000
Publication Date: 2000-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 53
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