M.A. Samee

FT-IR and Raman spectroscopic studies of ZnF2–ZnO–As2O3–TeO2 glasses

Abstract The effect of fluorine substitution on the spectral properties of the xZnF2–(20-x)ZnO–40As2O3–40TeO2 (x = 0, 4, 8, 12, 16 and 20 mol%) glass system was investigated by FTIR and Raman spectroscopies. The results demonstrate that TeO4 and TeO3 were among the primary structural units in the investigated glasses in addition to As2O3 pyramids and ZnO4 structural units. The addition of fluorine results in the reduction of Te–O–Te linkage due to a gradual transformation of trigonal bipyramidal TeO4 through TeO3+1 to trigonal pyramidal TeO3, which decreases the connectivity of the tellurite glass former network. The theoretical optical basicity of the studied glasses decreases with increasing ZnF2 content.

MIXED ALKALI EFFECT IN (40-x)K2O–xLi2O-10Na2O–50B2O3 GLASSES—PHYSICAL AND OPTICAL ABSORPTION STUDIES

So far only a handful of publications have been concerned with the study of the mixed alkali effect in borate glasses containing three types of alkali ions. In the present work, the mixed alkali effect (MAE) has been investigated in the glass system (40–x) K2O–x Li2O –10Na2O–50B2O3.(0≤x≤40 mol%) through density and modulated DSC studies. The density and glass transition temperature of the present glasses varies non-linearly exhibiting mixed alkali effect. We report the mixed alkali effect in the present glasses through optical properties. From the absorption edge studies, the various values of optical band gap (Eo) and Urbach energy (ΔE) have been evaluated. The values of Eo and ΔE show non-linear behavior with compositional parameter showing the mixed alkali effect. The band gap energy based average electronic polarizability of oxide ions αO2–(Eo), optical basicity A(Eo), and Yamashita–Kurosawa’s interaction parameter A(Eo) have been examined to check the correlations among them and bonding character. Based on good correlation among electronic polarizability of oxide ions, optical basicity and interaction parameter, the present K2O– Li2O–Na2O–B2O3 glasses are classified as normal ionic (basic) oxides.

Physical, Optical absorption and EPR studies on fluoro- bismuthate glasses

Glasses of the xLiF-(50-x)Li2O-20SrO-30Bi2O3 system, with 0 ≤ x ≤ 20 mole % were studied by EPR and Optical measurements. The changes in both density and molar volume indicate structural modifications occur due to addition of LiF. The glass transition temperatures are observed to decrease with an increase in LiF content in the compositions. The local structure around Cu2+ ions has been examined by means of electron paramagnetic resonance and optical absorption measurements. It is observed that the spin-Hamiltonian parameters calculated from the EPR spectra are influenced by the glass composition. The Cu2+ ions are in well-defined axial sites but subjected to small distortion leading to the broadening of the spectra. The spin-Hamiltonian parameter values indicate that the ground state of Cu2+ is and the site symmetry around Cu2+ ions is tetragonally distorted octahedral. The optical absorption spectra exhibited a broad band corresponding to the d-d transition bands of Cu2+ ion. By correlating EPR and optical absorption data, the bond parameters are evaluated.

Thermal and elastic properties of oxy-fluoro zinc tellurite glasses

A glass system based on ZnF2−ZnO−As2O3−TeO2 was prepared. A number of properties such as glass transition temperature, glass stability, Elastic moduli, Debye temperature, poisons ratio studies. The results indicated that most of the properties are observed to be dependent on ZnF2 content.

OPTICAL PROPERTIES ON Li2O-K2O-WO3-B2O3 GLASS SYSTEM

Mixed alkali tungsten borate glasses xLi2O–(30–x) K2O–10WO3–60B2O3 (0 < x < 30) were prepared from the melts. These glasses were characterized using X-ray diffraction, differential scanning calorimetry and density measurements. Optical absorption studies were carried out as a function of alkali content to look for mixed alkali effect (MAE) on the spectral properties of these glasses. From the study of ultraviolet absorption edge, the optical band gap energies and Urbach energies were evaluated. The average electronic polarizability of the oxide ion, optical basicity and the interaction parameters were also evaluated for all the glasses. Many of these parameters vary non-linearly exhibiting a minima or maxima with increasing alkali concentration, indicating the mixed alkali effect. An attempt is made to interpret MAE in this glass system in terms of its glass structure.

Mixed mobile ion effect on a.c. conductivity of boroarsenate glasses

In this article we report the study of mixed mobile ion effect (MMIE) in boroarsenate glasses. DSC and a.c. electrical conductivity studies have been carried out for

Physical and optical properties of zinc arsenic tellurite glasses

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Physical and optical studies in mixed alkali borate glasses with three types of alkali ions

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Mixed alkali tungsten borate glasses – Optical and structural properties

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