Hunting for hydrogen: random structure searching and prediction of NMR parameters of hydrous wadsleyite.

Hunting for hydrogen: random structure searching and prediction of NMR parameters of hydrous wadsleyite† †Electronic supplementary information (ESI) available: Further information on the structures generated by AIRSS, alternative structural models, supercell calculations, total enthalpies of all computed structures and further information on 1H/2H NMR parameters. Example input and all raw output files from AIRSS and CASTEP NMR calculations are also included. See DOI: 10.1039/c6cp01529h Click here for additional data file.

Forsterite, hydrous and anhydrous wadsleyite and ringwoodite (Mg2SiO4): 29Si NMR results for chemical shift anisotropy, spin-lattice relaxation, and mechanism of hydration

We present a detailed 29Si NMR spectroscopic study of isotopically enriched samples of forsterite and of anhydrous and hydrous wadsleyite and ringwoodite (α, β, and γ phases of Mg2SiO4), which complement previous extensive studies of these minerals by XRD and vibrational spectroscopy. VISi is not detected in any of the phases at levels of about 0.1 to 0.5%. When coupled with recent theoretical ...

Wadsleyite II: A new high pressure hydrous phase in the peridotite-H2O system

A new hydrous silicate phase with formula Mg1.71Fe0.177Al0.01Si0.965H0.332O4 has been synthesized at 1400°C and 17.5GPa from a hydrous iron-rich mantle peridotite composition. The space group is Imma and unit cell parameters a = 5.6884(4); b = 28.9238(15); and c = 8.2382(6)Å, so that a and c are approximately those of wadsleyite, whereas b is 2.5 times that of wadsleyite. The calculated density...

Quantitative analysis of hydrogen sites and occupancy in deep mantle hydrous wadsleyite using single crystal neutron diffraction

Evidence from seismological and mineralogical studies increasingly indicates that water from the oceans has been transported to the deep earth to form water-bearing dense mantle minerals. Wadsleyite [(Mg, Fe2+)2SiO4] has been identified as one of the most important host minerals incorporating this type of water, which is capable of storing the entire mass of the oceans as a hidden reservoir. To...

High-pressure Raman spectroscopic study of Fo90 hydrous wadsleyite

Raman spectra of monoclinic Fo90 hydrous wadsleyite with 2.4 wt% H2O have been measured in a diamond-anvil cell with helium as a pressure-transmitting medium to 58.4 GPa at room temperature. The most intense, characteristic wadsleyite modes, the Si–O– Si symmetric stretch at 721 cm 1 and the symmetric stretch of the SiO3 unit at 918 cm , shift continuously to 58.4 GPa showing no evidence of a f...