High pressures join carbon dioxide and silica

Un nuovo composto con formula chimica C0.6Si0.4O2 è stato sintetizzato in condizioni estreme di pressione (~20 GPa) e temperatura (~5000 K), facendo reagire due sostanze precedentemente ritenute incompatibili: l’anidride carbonica, un gas, e la silice, un solido. Questa scoperta, basata su misure di spettroscopia ottica e diffrazione di raggi X, aggiorna la corrente visione della tabella periodica e potrebbe essere di grande rilievo per le scienze della terra e dei pianeti.A novel compound with formula C0.6Si0.4O2 has been synthesized at extreme pressure (~20 GPa) and temperature (~5000 K) conditions through the reaction of two materials previously thought to be incompatible: carbon dioxide, a gas, and silica, a solid. These findings, based on optical spectroscopy and X-ray diffraction measurements, update our view of the periodic table and could be of paramount significance for Earth and planetary sciences

Crystal structure of solid Oxygen at high pressure and low temperature

Results of X-ray diffraction experiments on solid oxygen at low temperature and at pressures up to 10 GPa are presented.A careful sample preparation and annealing around 240 K allowed to obtain very good diffraction patterns in the orthorhombic delta-phase. This phase is stable at low temperature, in contrast to some recent data [Y. Akahama et al., Phys. Rev. B64, 054105 (2001)], and transforms with decreasing pressure into a monoclinic phase, which is identified as the low pressure alpha-phase. The discontinuous change of the lattice parameters, and the observed metastability of the alpha-phase increasing pressure suggest that the transition is of the first order.Comment: 4 pages with three figure

Flexibility windows and compression of monoclinic and orthorhombic silicalites

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Lattice dynamics of dense lithium.

We report low-frequency high-resolution Raman spectroscopy and ab-initio calculations on dense lithium from 40 to 200 GPa at low temperatures. Our experimental results reveal rich first-order Raman activity in the metallic and semiconducting phases of lithium. The computed Raman frequencies are in excellent agreement with the measurements. Free energy calculations provide a quantitative description and physical explanation of the experimental phase diagram only when vibrational effect are correctly treated. The study underlines the importance of zero-point energy in determining the phase stability of compressed lithium

Annual Catalogue of the Minnesota State Normal School at Moorhead. Seventh Year. (1894-1895)

https://red.mnstate.edu/bulletins/1064/thumbnail.jp

Spectroscopic study of intermolecular interactions in solid oxigen under pressure

Dottorato di ricerca in fisica. 12. ciclo. Supervisore Fabrizio BarocchiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Spectroscopic study of intermolecular interactions in solid oxigen under pressure

Dottorato di ricerca in fisica. 12. ciclo. Supervisore Fabrizio BarocchiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal