Enstatite, Mg2Si206: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration
Abstract
Synthetic enstatite, Mg2Si206, is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) Å at 23°C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F2) = 0.032, yielding Mg – O and Si – O bond lengths with standard deviations of 0.0007 and 0.0008 Å, respectively. The variations observed in the Si – O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron A. The smallest O – Si – O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent [SiO4] tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si – O bond lengths as large as + 0.002 Å at room temperature.
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- Fehlordnung bei Verbindungen MX3 mit Schichtenstruktur I. Berechnung des Intensitätsverlaufs auf den Streifen der diffusen Röntgenstreuung
- Fehlordnung bei Verbindungen MX3 mit Schichtenstruktur II. Analyse der Fehlordnung im Wismuttriiodid
- Effect of inaccessible volumes accompanied by symmetry elements on cumulative distribution functions
- Groups of simple and multiple antisymmetry of layers
- Electron diffraction intensity calculation and image simulation considering absorption for germanium and gold
- Structures of two modifications of Ca3GeO5
- Transverse quadratic electrostrictive effect in alkali halides with the NaCl structure*
Articles in the same Issue
- Enstatite, Mg2Si206: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration
- Crystal structure of 5-benzene sulphonamido 3-phenyl 1,2,4-triazole
- A study of decomposition methods for refinement of H+-ZSM5 zeolite with powder diffraction data
- Polytypes and polytypism
- Copper(II) silicates and germanates with chain structures I. CaCuGe2O6, a strongly deformed pyroxene*
- Copper(II) silicates and germanates with chain structures II. Crystal chemistry *
- Fehlordnung bei Verbindungen MX3 mit Schichtenstruktur I. Berechnung des Intensitätsverlaufs auf den Streifen der diffusen Röntgenstreuung
- Fehlordnung bei Verbindungen MX3 mit Schichtenstruktur II. Analyse der Fehlordnung im Wismuttriiodid
- Effect of inaccessible volumes accompanied by symmetry elements on cumulative distribution functions
- Groups of simple and multiple antisymmetry of layers
- Electron diffraction intensity calculation and image simulation considering absorption for germanium and gold
- Structures of two modifications of Ca3GeO5
- Transverse quadratic electrostrictive effect in alkali halides with the NaCl structure*
