Spin crossover of iron is of central importance in solid Earth geophysics. It impacts all physical properties of minerals that altogether constitute ∼95 vol% of the Earth’s lower mantle: ferropericlase [(Mg,Fe)O] and Fe-bearing magnesium silicate (MgSiO3) perovskite. Despite great strides made in the past decade, the existence of an intermediate-spin (IS) state in ferrous iron (Fe2+) (with tota...

The electronic spin and valence states of iron in lower-mantle silicate perovskite have been previously investigated at high pressures using various experimental and theoretical techniques. However, experimental results and their interpretation remain highly debated. Here we have studied a wellcharacterized silicate perovskite starting sample [(Mg0.9,Fe0.1)SiO3] in a chemically inert Ne pressur...

A new compound with a non-centrosymmetric structure, potassium tetra-kis-[dioxomolybdenum(IV)] arsenate trioxide, K(MoO2)4O3(AsO4), has been synthesized by a solid-state reaction. The [(MoO2)4O3(AsO4)](+) three-dimensional framework consists of single arsenate AsO4 tetra-hedra, MoO6 octa-hedra, MoO5 bipyramids and bi-octa-hedral units of edge-sharing Mo2O10 octa-hedra. The [Mo2O8]∞ octa-hedral ...

Crystallographic preferred orientation (CPO) of post-perovskite (Mg,Fe)SiO3 (pPv) has been believed to be one potential source of the seismic anisotropic layer at the bottom of the lower mantle (D″ layer). However, the natural CPO of pPv remains ambiguous in the D″ layer. Here we have carried out the deformation experiments of pPv-(Mg0.75,Fe0.25)SiO3 using synchrotron radial X-ray diffraction i...

We have studied the mineral poldervaartite CaCa[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Therm...

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2-CHSi(OMe)3)n-RF (RF-(VM)n-RF)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)3] under alkaline conditions to afford the corresponding fluorinated oligomeric silica nanocomposites containing gluconamide units [RF-(VM-SiO3/2)n-RF/Glu-SiO3/2]. These obtained nanocomposites were appl...

The crystal chemistry of ten well-characterized bridgmanite single-crystals with Fe and Al contents ranging from 0 to 0.40 atoms per two-cation formula units were investigated by single-crystal X-ray diffraction. Structural refinements indicate that Fe3+ mainly occupy the Mg Si sites, respectively, when present in similar proportions. Molar volumes endmember components refined using data this p...