Neutron and X-ray diffraction study of hydrogarnet Ca3Al2(O4H4)3

The crystal structure of Ca3Al2(O4D4)3 was refined from time-of-flight neutron powder data collected at 300, 200 and 100 K. The D atom is located 0.906(1) A (300 K) from oxygen surrounding the vacant 4 tetrahedral site. With the complete replacement of Si4+ by 4H+ in the grossular structure, the tet...

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Bibliographic Details
Published in:The American mineralogist 1987-08, Vol.72 (7-8), p.756-765
Main Authors: Lager, G. A, Armbruster, Thomas, Faber, J
Format: Article
Language:English
Subjects:
crystal structure
experimental studies
garnet group
garnet structure
hydrates
hydrogarnet
hydrogrossular
mineral data
Mineralogy
minerals
nesosilicates
neutron diffraction analysis
orthosilicates
refinement
silicates
synthesis
X-ray data
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Summary:The crystal structure of Ca3Al2(O4D4)3 was refined from time-of-flight neutron powder data collected at 300, 200 and 100 K. The D atom is located 0.906(1) A (300 K) from oxygen surrounding the vacant 4 tetrahedral site. With the complete replacement of Si4+ by 4H+ in the grossular structure, the tetrahedral d-O distance increases from 1.645 to 1.950 A. Structural adjustments in response to tetrahedral expansion include a decrease in the length of the shared octahedral edge relative to the unshared edge and a corresponding increase in the (Ca(1)-O(4) distance in the dodecahedron.
ISSN:0003-004X
1945-3027