0000000000281665
AUTHOR
Antonino Marco Saitta
Sixfold coordinated phosphorus by oxygen in AlPO4 quartz homeotype under high pressure.
International audience; AlPO4 belongs to the berlinite quartz homeotype family, which has been the subject of intense high pressure research triggered by the supposed existence of reversible pressure induced amorphization. New x-ray diffraction experiments, complemented with ab initio calculations, demonstrate the existence of two high pressure crystalline polymorphs and show that AlPO4 share the same two stage densification mechanism as silica. In first place a compact hexagonal sublattice of oxygen atoms is formed. In a second step the cations redistribute in the interstices giving rise to a monoclinic distorted CaCl2 phase. The most outstanding feature of the new phase is that phosphorou…
Vibrational properties of delafossiteCuGaO2at ambient and high pressures
In this paper we investigate the vibrational properties of $\mathrm{Cu}\mathrm{Ga}{\mathrm{O}}_{2}$ delafossite by means of Raman experiments and ab initio calculations. Both investigations have been performed at ambient pressure and also at high pressure. The two Raman-active modes have frequencies ${w}_{{E}_{g}}=368\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ and ${w}_{{A}_{1g}}=729\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, and pressure coefficients $2.78\ifmmode\pm\else\textpm\fi{}0.03\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}∕\mathrm{GPa}$ $({E}_{g})$ and $4.64\ifmmode\pm\else\text…