We investigate charge-balanced hydrous magnesium and silicon defects [(2H)Mg, (4H)X Si] by first principles. Two new lowest-energy hydrogen configurations are proposed for (4H)Si. With these new configurations, the distribution of O-H stretching phonon frequencies in Group I (>3450 cm–1) are better reproduced. Substitution of silicon with four hydrogen atoms gives rise to significant elongation...

In water treatment, adsorption & ion exchange are usually used on the stage of deep purification when higher selectivity to toxic molecules and ions is needed. Inorganic ion exchangers are that class of the adsorptive materials which, if developed by the advanced synthesis approaches, are capable to lower the concentrations of target anions up to the level requesting by World Health Organizatio...

[1] The effect of H2O on harzburgite-saturated melts has been quantified with a series of hydrous and anhydrous melting experiments using a piston-cylinder device. Experimental conditions were 1.2–2.2 GPa and 1175–1500!C. Melt H2O contents range from 0 to 10 wt %. The effects of temperature, pressure, and bulk composition (including H2O) on the SiO2 content of the experimental melts have been e...

[1] Knowledge about the properties of silicate melts is needed by volcanologists and petrologists to evaluate the dynamics of volcanic eruptions and magmatic processes. These properties include the solubility and diffusivity of volatile components in silicate melts, silicate melt viscosity, and the fragmentation condition. Data and models of each property are reviewed and assessed. For rhyoliti...

[1] Knowledge of the pressure effect on elasticity of hydrous olivine polymorphs is necessary to model seismic wave speeds for potential hydrous regions of the mantle. Here we report single-crystal elastic properties of wadsleyite, b-Mg2SiO4, with 0.84 wt.% H2O measured to 12 GPa by Brillouin scattering. Pressure derivatives of the aggregate bulk modulus, KS0, and shear modulus, G 0 0, of hydro...

Recent experiments show evidence of fluctuating magnetism in δ-Pu. This has direct consequences for the atomic volume of this metal phase and gives a simple explanation for its anomalously low density. Earlier there has from the experimental community been a strong emphasis on the absence of magnetism in Pu, a view which has severely delayed the development of a proper description of the physic...

[1] The cause of seismic anisotropy exhibiting trench parallel fast directions in subduction systems has been the subject of significant recent research. We provide new constraints on the contributions of hydrous phases to seismic anisotropy from an unusually well-localized region of trench parallel fast directions in Rayleigh wave phase velocities near the Cascade arc at 45 to 66 s periods. We...

Hydrous bismuth oxides (HBO2) have been reported to have anionic sorptive properties. In the present study, removal of fluoride from aqueous solution has been explored for its possible application in drinking water treatment. The performance of fluoride removal from aqueous solutions has been studied by adding four cationic ligands (Fe, Mg, Ca and Cu) in the matrix of hydrous bismuth oxide (HBO...

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...

The distribution of the rare earths and yttrium (REY) in co-existing hydrous Mn oxides and Fe oxides that form marine hydrogenetic ferromanganese crusts is used to better describe the partitioning and fractionation of the REY between these (hydr)oxides and seawater in the natural marine system. Four fractions (easily exchangeable, Mn-oxide-bound, Fe-oxidebound, and insoluble-residue-bound REY) ...