Avadhesh Kumar Yadav

A review of the structures of oxide glasses by Raman spectroscopy

The family of oxide glasses is very wide and it is continuously developing. The rapid development of advanced and innovative glasses is under progress. Oxide glasses have a variety of applications in articles for daily use as well as in advanced technological fields such as X-ray protection, fibre glasses, optical instruments and lab glassware. Oxide glasses basically consist of network formers, such as borate, silicate, phosphate, borosilicate, borophosphate, and network modifiers such as alkali, alkaline earth and transition metals. In the present review article, Raman spectroscopy results for the structures of borate, silicate, phosphate, borosilicate, borophosphate, aluminosilicate, phosphosilicate, alumino-borosilicate and tellurite glasses are summarized.

A Review on Infrared Spectroscopy of Borate Glasses with Effects of Different Additives

Borate glasses are the technologically important class of glasses and play a significant role in various applications. Borate glasses contain planar BO3 groups as structural units, rather than tetrahedral SiO4 groups. The oxygen atoms are, as in SiO2, again connected to two network-forming atoms, in case of boron. The radial distribution analysis describes the B2O3 glass structure as consisting of boroxol rings, that is, planar rings containing three boron atoms and three oxygen atoms. The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth. These additives also work as a network modifier and a nucleating agent for crystallization of glass. Therefore, the optical properties of the borate glasses have been changed significantly.

Structural and crystallization behavior of (Ba,Sr)TiO3 borosilicate glasses

Various glass samples were prepared by melt quench technique in the glass system [(Ba1− x Sr x ) TiO3]–[2SiO2–B2O3]–[K2O] doped with 1 mole% of La2O3. Infrared spectra show the number of absorption peaks with different spliting in the wave number range from 450 to 4000 cm−1. Absorption peaks occurs due to asymetric vibrational streching of borate by relaxation of the bond B–O of trigonal BO3. Raman spectra show the Raman bands due to ring-type metaborate anions, symmetric breathing vibrations BO3 triangles replaced by BO4 tetrahedra, and symmetric breathing vibrations of six-member rings. The differential thermal analysis of a glass sample corresponding to composition x = 0.0 shows crystallization temperature at 847°C and glass transition temperature at 688°C. X-ray diffraction (XRD) pattern of glass ceramic samples shows the major crystalline phase of BaTiO3 whereas pyrochlore phases of barium titanium silicate. Scanning electron micrographs confirm the results of XRD as barium titanate is major crystalline phase along with pyrochlore phase of barium titanium silicate.

Crystallization and dielectric properties of Fe2O3 doped barium strontium titanate borosilicate glass

An attempt has been made to prepare barium strontium titanate borosilicate glasses in the system, 64[(Ba1−xSrx)·TiO3]–30[2SiO2·B2O3]–5[K2O]–1[Fe2O3] (0.4 ≤ x ≤ 1.0), using the conventional melt-quench method. The prepared glasses were characterized by differential thermal analysis, X-ray diffraction, scanning electron microscopy and impedance spectroscopy techniques. On the basis of the DTA results, the glasses were crystallized via regulated heat treatment process. The activation energy for crystallization was 818 ± 1.6 kJ mol−1. A high dielectric constant of about 107 070 was obtained for the 6 hour heat treated glass ceramic sample. Fe2O3 plays an important role in enhancing crystallization, dielectric constant and retardation of dielectric loss in the samples.

Synthesis, Structural and Optical Studies of Barium Strontium Titanate Borosilicate Glasses Doped with Ferric Oxide

Various barium strontium titanate borosilicate glasses were prepared by a rapid melt-quench technique. Spectroscopic studies have been carried out on investigated glasses for their structural information. Infrared and Raman spectroscopic studies showed that these glasses are formed by glass-forming network of borate and silicate as well as network modifiers in the form of cations of alkaline earth atoms. The borate and silicate networks are modified by barium, strontium, titanium, and iron cations in glass matrix. The network of triborate unit is modified in tetraborate unit by adding ferric oxide in a glassy matrix. The optical studies are performed by ultraviolet-visible spectroscopy and it confirms that the band gap decreases with increase in the concentration of ferric oxide.

Mechanical and dielectric behaviors of perovskite (Ba,Sr)TiO 3 borosilicate glass ceramics

Perovskite (Ba,Sr)TiO3 glass ceramics were crystallized in the presence of La2O3 for glass ceramic system [(Ba1−xSrx)TiO3]-[2SiO2-B2O3]-[K2O]-[La2O3] (x = 0.0 and 0.4). The formation of major crystalline phase of BaTiO3 along with secondary phase of Ba2TiSi2O8 was confirmed by X-ray diffraction (XRD) studies. Major crystalline phase was clearly seen in the micrographs of (Ba,Sr)TiO3 borosilicate glass ceramic samples. The prepared glass ceramic samples showed very high values of toughness and elastic modulus. Barium strontium titanate (BST) glass ceramics are used in barrier layer capacitors for storage of high energy due to their very high dielectric constant and low dielectric loss.