Structure and properties of CaF<Subscript>2</Subscript>–B<Subscript>2</Subscript>O<Subscript>3</Subscript> glasses

FTIR spectroscopy has been employed to investigate the structure of CaF₂–B₂O₃ glasses. It is proposed that CaF₂ partially modifies the borate network forming \textCa _{1 / 2} ²⁺ [\textBO _{3 / 2} \textF] ^- {\text{Ca}}_{ 1 / 2}^{ 2+ } [{\text{BO}}_{ 3 / 2} {\text{F]}}^{ - } units. The rest of CaF₂ is assumed to build an amorphous network formed of CaF₄ tetrahedra. Analysis of density and molar volume revealed that the volume of CaF₄ tetrahedron in the studied glasses is slightly greater than that in the crystalline form. Data of density, molar volume, and electric conductivity have been correlated with the glass structure. As far as the authors know, CaF₂–B₂O₃ glasses are investigated for the first time.     

Density-structure predictions of silicate glasses containing Ga2O3

The density data of Li₂O-, Na₂O-, CaO- and BaO-Ga₂O₃-SiO₂ glasses have been analyzed. The analysis is based on a structural model predicted from the results of the current spectroscopic investigations. It is assumed that for (R₂O or RO)/Ga₂O₃ = 1 the modifier oxide is used only by the gallate network to form GaO₄ tetrahedra without non-bridging oxygen ions. For 1 < (R₂O or RO)/Ga₂O₃ 2 the excess of modifier form non-bridging oxygen ions in the gallate network. There is a remarkable difference between the determined and the calculated density for Ga₂O₃/SiO₂ > 0.75. This is suggestive for a different distribution of the modifier oxide between the two networks. Empirical relations have been obtained to calculate the density as a function of the composition.     

Structural studies and physical properties of Gd2O3-doped borate glass

Journal of Materials Science: Materials in Electronics - Gd2O3-doped glasses in the B2O3–CaO–Na2O–SrO–P2O5 system were synthesized via melt annealing route and characterized...     

Structural and Dielectric Studies on Na2O-PbO-SiO2 Glasses

Silicon - Structural studies on x Na2O.(50-x)PbO.50SiO2 glasses have been carried out by different spectroscopic techniques. FTIR, EDX, NMR and dielectric spectroscopies are applied to follow the...     

Characterization of New Categories of Bioactive Based Tellurite and Silicate Glasses

New types of tellurite glass ceramics were prepared and studied from the viewpoint of bioactivity. The obtained results were compared with those of silicate glass ceramics. The crystallization behaviors of both silicate and tellurite glass ceramics with equal ratio of CaO/P₂O₅ were investigated. The silicate glass samples were transformed to glass ceramics by a thermal treatment process. While the tellurite glass ceramics were directly obtained without any thermal treatment. The microstructure of these materials was characterized by X-ray diffraction (XRD), Fourier transform infrared absorption spectroscopy (FTIR) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (SEM/EDX). The results revealed clear proof that TeO₂ promoted the nucleation and crystallization processes which led to the formation of different crystalline bio-phases. While the silicate glasses showed a much lower degree of crystallinity than that presented by the tellurite glass ceramics. The crystals of tellurite containing glass were needle- like morphology, which is attributed to the one-dimensional rapid growth of the apatite-tellurite phase. On the other hand, a particle-like morphology is shown in the silicate glass matrix. Bioactivity of the glasses in simulated body fluids (SBF) was investigated. Tellurite containing glass ceramics showed a better bioactivity during the in vitro test than that of the silicate one. This was attributed to a great analogous between the morphology of crystals of tellurite glass and the morphology of hydroxyapatite in human bone, since both possess a needle-like morphology.     

Structural Investigation of PVC/PS Polymer Blend Doped with Nanosilica from a Renewable Source

Silicon - Virgin samples of equivalent mass fractions from a PVC/PS (polyvinyl chloride/polystyrene) polymer blend were prepared together with other samples of the same composition containing...