Dispersion, ionic bonding and vibrational shifts in phospho-aluminosilicate glasses.

Understanding the relationships between structure and properties of aluminosilicate glasses is of interest in magmatic studies as well as for glass applications as mechanical or optical components. Glass properties may be tailored by the incorporation of additional elements, and here we studied the effect of phosphate incorporation on refractive index and the degree of ionic bonding in aluminosilicate glasses. The studied glasses in the system SiO-AlO-NaO-PO had a metaluminous composition (Al:Na = 1) with the content of SiO ranging from 50 to 70 mol% and of PO from 0 to 7.

Zinc borate glasses: properties, structure and modelling of the composition-dependence of borate speciation.

The short-range order of binary zinc borate glasses, ZnO-(1-)BO, has been quantitatively described as a function of ZnO content over the entire glass forming range for the first time, to the best of our knowledge. Multiple spectroscopic techniques (B NMR, Raman, infrared) reveal detailed structural information regarding borate speciation and network connectivity, and a new model for quantifying the molar fractions of short-range order units is proposed. A consistent thermal history dependence for the fraction of tetrahedral boron () is well accounted for by the proposed model.

Pressure-Induced Structural Transformations and Electronic Transitions in TeO Glass by Raman Spectroscopy.

TeO glass has been studied by Raman spectroscopy up to the record pressure of 70 GPa. The boson peak frequency ω exhibits a decrease of the ∂ω/∂ slope at 5-6 GPa and saturates above 30 GPa with a practically constant value up to 70 GPa. Experiment and theory indicate that pressures up to 20 GPa induce the transformation of single Te-O-Te bridges to double Te-O-Te bridges, leading to a more compact structure, while Raman activity developing at higher pressures around 580 cm signals the increase of Te coordination from 4- to 6-fold.

Influence of Phosphate on Network Connectivity and Glass Transition in Highly Polymerized Aluminosilicate Glasses.

Melt-derived metaluminous (Al/Na = 1) aluminosilicate glasses in the system SiO-AlO-NaO-PO were prepared with PO and SiO contents varying from 0 to 7.5 and 50 to 70 mol %, respectively. The glass structure was investigated by X-ray absorption near edge structure, far- and medium-infrared, and polarized Raman spectroscopic techniques.

On the Absence of Doubly Bonded Te═O Groups in TeO Glass.

Tellurium oxide clusters (TeO) were investigated through density functional theory to gain information on the structure of TeO glass. Among a large number of stable conformers studied, a cyclic, nonsymmetric structure was optimized without terminal Te═O double bonds. The dimer of this structure, (TeO), gives calculated Raman and infrared spectra in very good agreement with the experimental ones, with its total pair distribution function being also in agreement with results of neutron and high-energy X-ray diffraction studies.

Anion polarizabilities in oxynitride glasses. Establishing a common optical basicity scale.

Inspired by the work of John Duffy on optical basicity of oxyfluoride glasses, we apply here the concept of optical basicity to oxynitride systems. While in the original work of Duffy and Ingram the basicity of a medium could be probed by s ions like Pb, the low energy intrinsic absorption edge of nitride-containing systems does not allow the use of such probe ions. This study uses therefore experimental data on refractive index and density of alkaline earth and rare earth containing silicate oxynitride glasses, prepared by the authors or taken from the literature.

Structural Stability, Vibrational Properties, and Photoluminescence in CsSnI Perovskite upon the Addition of SnF.

The CsSnI perovskite and the corresponding SnF-containing material with nominal composition CsSnIF were synthesized by solid-state reactions and structurally characterized by powder X-ray diffraction. Both materials undergo rapid phase transformation upon exposure to air from the black orthorhombic phase (B-γ-CsSnI) to the yellow orthorhombic phase (Y-CsSnI), followed by irreversible oxidation into CsSnI within several hours. The phase transition occurs at a significantly lower rate in the SnF-containing material rather than in the pure perovskite.

Structure and properties of orthoborate glasses in the Eu2O3-(Sr,Eu)O-B2O3 quaternary.

The structure and properties of melt-quenched glasses and partially crystallized samples from the borate series (1-2x)Eu2O3-x((Eu,Sr)O-B2O3) were investigated in the supermodified regime of x < 0.5, using Raman, infrared (IR), electron spin resonance (ESR), and UV-vis absorption and fluorescence spectroscopic techniques. ESR and optical spectroscopy showed that, despite the strongly reducing synthesis conditions, the Eu(2+)/Eu(3+) equilibrium remained shifted to the side of trivalent Eu(3+).

Partitioning and structural role of Mn and Fe ions in ionic sulfophosphate glasses.

Ionic sulfophosphate liquids of the type ZnO-Na2O-Na2SO4-P2O5 exhibit surprising glass forming ability, even at slow or moderate cooling rate. As a concept, they also provide high solubility of transition metal ions which could act as cross-linking sites between the sulfate and phosphate entities. It is therefore investigated how the replacement of ZnO by MnO and/or FeO affects the glass structure and the glass properties.

Composition and temperature dependence of cesium-borate glasses by molecular dynamics.

The structural aspects of xCs2O-(1-x)B2O3 glasses have been investigated by molecular dynamics as functions of Cs2O content (x=0.2, 0.3, and 0.