Identification of paramagnetic centers in irradiated Sn-doped silicon dioxide by first-principles.

We present a first-principles investigation of Sn paramagnetic centers in Sn-doped vitreous silica based on calculations of the electron paramagnetic resonance (EPR) parameters. The present investigation provides evidence of an extended analogy between the family of Ge paramagnetic centers in Ge-doped silica and the family of Sn paramagnetic centers in Sn-doped silica for SnOconcentrations below phase separation. We infer, also keeping into account the larger spin-orbit coupling of Sn atoms with respect to Ge atoms, that a peculiar and highly distorted three-fold coordinated Sn center (i.

Seven-Coordinated High-Pressure Phase of CrSb and Experimental Equation of State of Sb ( = Cr, Fe, Ru, Os).

The Sb compounds with = Cr, Fe, Ru, and Os have been investigated under high pressures by synchrotron powder X-ray diffraction. All compounds, except CrSb, were found to retain the marcasite structure up to the highest pressures (more than 50 GPa). In contrast, we found that CrSb has a structural phase transition around 10 GPa to a metastable, MoP-type structure with Cr coordinated to seven Sb atoms.

High-Pressure, High-Temperature Studies of Phase Transitions in SrOsO─Discovery of a Post-Perovskite.

Using a recently developed method for in situ high-pressure, laser heating experiments in diamond anvil cells, we obtained a novel post-perovskite phase of SrOsO. The phase transition from perovskite SrOsO was induced at 44 GPa and 1350 K in a diamond anvil cell and characterized with synchrotron powder X-ray diffraction. The newly obtained post-perovskite is quenchable and Le Bail refinements under ambient conditions yielded the unit cell parameters: = 3.

Structure and Surface Relaxation of CeO Nanoparticles Unveiled by Combining Real and Reciprocal Space Total Scattering Analysis.

We present a combined real and reciprocal space structural and microstructural characterization of CeO nanoparticles (NPs) exhibiting different crystallite sizes; ~3 nm CeO NPs were produced by an inverse micellae wet synthetic path and then annealed at different temperatures. X-ray total scattering data were analyzed by combining real-space-based Pair Distribution Function analysis and the reciprocal-space-based Debye Scattering Equation method with atomistic models. Subtle atomic-scale relaxations occur at the nanocrystal surface.

Pseudopotentials of Elements for Solid-State NMR.

Computational methods are increasingly used to support interpreting, assigning and predicting the solid-state nuclear resonance magnetic spectra of materials. Currently, density functional theory is seen to achieve a good balance between efficiency and accuracy in solid-state chemistry. To be specific, density functional theory allows the assignment of signals in nuclear resonance magnetic spectra to specific sites and can help identify overlapped or missing signals from experimental nuclear resonance magnetic spectra.