• journal_title：American Mineralogist
• Contributor：Dmitry L. Lakshtanov ; Konstantin D. Litasov ; Stanislav V. Sinogeikin ; Holger Hellwig ; Jie Li ; Eiji Ohtani ; Jay D. Bass
• Publisher：Mineralogical Society of America
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2007.2294
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：92
• issue：7
• firstpage：1026
• section：Articles

X-ray diffraction, Brillouin, and Raman scattering measurements were performed on Al³⁺ and H⁺-bearing stishovite at ambient conditions. Samples with different Al³⁺ and H⁺ contents were used to examine the effects of these minor constituents on the density, acoustic velocities, single-crystal and aggregate elastic moduli. The X-ray diffraction and compositional data suggest that the incorporation mechanism of Al³⁺ into stishovite involves the formation of oxygen vacancies, in addition to the incorporation H⁺ in the structure. Our data show an overall linear decrease of the acoustic velocities, single crystal (c_ij) and aggregate (K₀, G₀) elastic moduli as a function of Al³⁺ concentrations. For the sample of stishovite containing 6.07(5) wt% Al₂O₃ and 0.24(2) wt% H₂O we obtained: zero-pressure adiabatic bulk modulus, K_S0 = 290(3) GPa, and the shear modulus, G_S0 = 207(2) GPa, with a calculated density of ρ = 4.16(1) g/cm³ based on X-ray diffraction. Stishovite containing 4.37(12) wt% Al₂O₃ and 0.29(3) wt% H₂O possesses higher aggregate moduli: K_S0 = 296(3) GPa and G_S0 = 213(2) GPa, with a calculated density of ρ = 4.21(1) g/cm³ based on X-ray diffraction. We conclude that the formation of oxygen vacancies has a stronger effect on the density and thus elastic properties of stishovite than does the incorporation of hydrogen.