Abstract
The crystal structure of OD-chondrodite [Mg5Si2O8(OD)2, P21/b (a unique), a = 4.74711(5), b = 10.34888(16), c = 7.90228(13) Å, α = 108.678(1)°] was refined to wRp = 0.0218, χ2 = 3.545 at ambient conditions using time-of-flight neutron powder data. The disordered H model proposed for OH-chondrodite on the basis of single-crystal X-ray data is confirmed. The occupations of the D1 and D2 sites are, respectively, 0.52(1) and 0.48(1). The long O5-D1 [1.076(4) Å] and O5-D2 [1.111(4) Å] bond lengths, which are two of the longest O-H(D) bonds observed in mineral structures, reflect the positional disorder of the O5 atom in the unshared OH-OH edge. Both D1 [1.968(4), 2.489(4) Å] and D2 [2.149(4), 2.251(4) Å] atoms are involved in two hydrogen bonds. A re-examination of the origin of positive OH frequency shifts in both F-bearing and OH-chondrodite at high pressure is warranted in view of the crystallographic data.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- Reply to Comment on “Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure”
Articles in the same Issue
- Self diffusion of Si and O in dacitic liquid at high pressures
- The effect of anhydrous composition on water solubility in granitic melts
- Stability and phase relations of Ca[ZnSi3]O8, a new phase with feldspar structure in the system CaO-ZnO-SiO2
- Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes: Evidence for a solvus relation between phlogopite and aspidolite
- The influence of T, aSiO₂, and fO₂ on exsolution textures in Fe-Mg olivine: An example from augite syenites of the Ilimaussaq Intrusion, South Greenland
- An experimental study of the external reduction of olivine single crystals
- Determination of site population in olivine: Warnings on X-ray data treatment and refinement
- Structural properties of ferromagnesian cordierites
- A calorimetric study of zoisite and clinozoisite solid solutions
- Mineralogy of lead in a soil developed on a Pb-mineralized sandstone (Largentière, France)
- Experimental mixtures of smectite and rectorite: Re-investigation of “fundamental particles” and “interparticle diffraction”
- Hydrothermal reactivity of Lu-saturated smectites: Part I. A long-range order study
- Hydrothermal reactivity of Lu-saturated smectites: Part II. A short-range order study
- Pulsed field gradient proton NMR study of the self-diffusion of H2O in montmorillonite gel: Effects of temperature and water fraction
- Structural environment and oxidation state of Mn in goethite-groutite solid-solutions
- Structure, compressibility, hydrogen bonding, and dehydration of the tetragonal Mn3+ hydrogarnet, henritermierite
- Electric field gradient tensors at the aluminum sites in the Al2SiO5 polymorphs from CCD high-resolution X-ray diffraction data: Comparison with 27Al NMR results
- Sodium cation dynamics in nitrate cancrinite: A low and high temperature 23Na and 1H MAS NMR study and high temperature Rietveld structure refinement
- O-D…O bond geometry in OD-chondrodite
- Refinement of hydrogen positions in synthetic hydroxyl-clinohumite by powder neutron diffraction
- In situ dehydration of yugawaralite
- Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure—Comment
- Reply to Comment on “Molecular dynamics simulation of phase transitions and melting in MgSiO3 with the perovskite structure”