Refractive Index and Optical Dispersion of In2O3, InBO3 and Gahnite

Refractive indices of In₂O₃, In₂₋ₓSnₓO₃, InBO₃ and 2 different gahnite crystals (ZnAl₂O₄ and Zn.₉₅Fe.₀₅Al₂O₄) were measured at wavelengths of 435.8 to 643.8 nm and were used to calculate n at λ = 589.3 nm ( nD ) and at λ = ∞ (n∞) using the one-term Sellmeier equation 1/(n²-1) = -A/λ² + B. Total polarizabilities, αₜₒₜₐₗ, were calculated from n∞ and the Lorenz-Lorentz equation. Refractive indices, nD and dispersion values, A, were, respectively, 2.093 x 10-16 m² and 133 x 10⁻¹⁶ m² for In₂O₃; 2.0755 and 138 x 10⁻¹⁶ m² for In₂₋ₓSnₓO₃; 1.7940 and 57 x 10⁻¹⁶ m² for ZnAl₂O₄ and 1.7995 and 56 x 10⁻¹⁶ m² for Zn.₉₅Fe.₀₅Al₂O₄ and n₀ = 1.8782 and ne = 1.7756 and x 10⁻¹⁶ m² for InBO₃.Please note: Authors differ slightly in the published version

InBO3 and ScBO3 at high pressures: an ab initio study of elastic and thermodynamic properties

We have theoretically investigated the elastic properties of calcite-type orthoborates ABO(3) (A= Sc and In) at high pressure by means of ab initio total-energy calculations. From the elastic stiffness coefficients, we have obtained the elastic moduli (B, G and E), Poisson's ratio (nu), B/G ratio, universal elastic anisotropy index (A(U)), Vickers hardness, and sound wave velocities for both orthoborates. Our simulations show that both borates are more resistive to volume compression than to shear deformation (B > G). Both compounds are ductile and become more ductile, with an increasing elastic anisotropy, as pressure increases. We have also calculated some thermodynamic properties, like Debye temperature and minimum thermal conductivity. Finally, we have evaluated the theoretical mechanical stability of both borates at high hydrostatic pressures. It has been found that the calcite-type structure of InBO3 and ScBO3 becomes mechanically unstable at pressures beyond 56.2 and 57.7 GPa, respectively. (C) 2016 Elsevier Ltd. All rights reserved.This study is supported by the Spanish MICINN projects MAT2013-46649-C4-2-P/3-P and MAT2015-71070-REDC. H.M.O., A.M., and P.R-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.A.S. acknowledges Juan de la Cierva fellowship program for financial support.Gomis, O.; Ortiz, HM.; Sans Tresserras, JÁ.; Manjón Herrera, FJ.; Santamaría-Pérez, D.; Rodríguez-Hernández, P.; Muñoz, A. (2016). InBO3 and ScBO3 at high pressures: an ab initio study of elastic and thermodynamic properties. Journal of Physics and Chemistry of Solids. 98:198-208. https://doi.org/10.1016/j.jpcs.2016.07.002S1982089

Optical Investigations of Intergrowth Effects in the Zeolite Catalysts ZSM-5 and ZSM-8

X-ray precession photographs and optical investigations of TPA-ZSM-5 (silicalite) and TEA-ZSM-8 zeolites reveal that ZSM-8 consists of two interpenetrating species rotated by 90° round the crystallographic c axis similarly to ZSM-5. The c axis of ZSM-5 coincides with refractive index nx, the c axis of ZSM-8 coincides with ny. The intergrowth species are differently shaped in ZSM-5 and ZSM-8. ZSM-5 consists of an orthorhombic prism penetrated by two pyramidal fragments. The ZSM-8 crystals studied here consist of species with two-dimensional hourglass-like shapes embedded in orthorhombic prisms. The orientations of the optical indicatrices of ZSM-5 and ZSM-8 are identical after calcination, Le., after removing or decomposing the template. This confirms recent work which showed that the framework structures of ZSM-5 and ZSM-8 are essentially identical