Time filter

Source Type

Edukondalu A.,Osmania University | Edukondalu A.,University of Hyderabad | Sripathi T.,Consortium for Scientific Research | Rahman S.,Osmania University | And 2 more authors.
Journal of Electronic Materials | Year: 2016

Glass with compositions xK2O-(30 − x)Li2O-10WO3-60B2O3 for 0 ≤ x ≤ 30 mol.% have been prepared using the normal melt quenching technique. The optical reflection and absorption spectra were recorded at room temperature in the wavelength range 300–800 nm. From the absorption edge studies, the values of the optical band gap (Eopt) and Urbach energy (ΔE) have been evaluated. The values of Eopt and ΔE vary non-linearly with composition parameter, showing the mixed alkali effect. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple Di-Domenico model. © 2016 The Minerals, Metals & Materials Society


Edukondalu A.,Osmania University | Srinivasu C.,Mahatma Gandhi Institute | Rahman S.,Osmania University | Sathe V.,Consortium for Scientific Research | Kumar K.S.,Osmania University
AIP Conference Proceedings | Year: 2014

Mixed alkali borate glasses of composition xLi2O-(30-x)K2O-10WO3-60B2O3 (0 ≤ x ≤ 30 mol%) were prepared by melt quench technique. The structure of present glass system was investigated by Raman spectroscopy. The characteristic bands of these glasses due to the stretching and bending vibrations were identified and analyzed by the increasing of alkali content. This fact allowed us to identify the specific structural units which appear in these glasses and thus to point out the network modifier role of alkali oxide for low concentrations and its former role at high concentrations. © 2014 AIP Publishing LLC.


Shinde S.S.,Shivaji University | Shinde P.S.,Korea Electrotechnology Research Institute | Sathe V.G.,Consortium for Scientific Research | Barman S.R.,Consortium for Scientific Research | And 2 more authors.
Journal of Molecular Structure | Year: 2010

Nanocrystalline zinc oxide (ZnO) thin films have attracted great attention due to their possible applications in optoelectronic devices. The dependence of size and catalyst (indium and fluorine) in ZnO thin films synthesized by spray pyrolysis technique was studied. To understand the chemical bonding structure and electronic states of the catalyst based ZnO thin films, XPS analysis was carried out. A comprehensive micro-Raman scattering study of the phonons in catalyst based ZnO thin films grown in ambient air was made. Low temperature dependent Raman spectroscopy studies were carried out for the detailed structures, vibrations, and in situ size variation of nanostructured thin films. The size and catalyst dependence of the coupling strength between electron and LO phonon was experimentally estimated. The coupling strength determined by the ratio of second to first-order Raman scattering cross sections was found to diminish with decreasing crystallite size, and the Fröhlich interaction plays the vital role in electron-phonon-coupling in ZnO. Influence of catalyst on the luminescence properties was investigated. © 2010 Elsevier B.V. All rights reserved.


Marathe S.,University of Pune | Koinkar P.,University of Pune | Ashtaputre S.,University of Pune | Sathe V.,Consortium for Scientific Research | And 2 more authors.
Thin Solid Films | Year: 2010

ZnO nanoneedles were coated on hot filament chemical vapour deposited diamond thin films to enhance the field emission properties of ZnO nanoneedles. The virgin diamond films and ZnO nanoneedles on diamond films were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The field emission studies reveal that the ZnO nanoneedles coated on diamond film exhibit better emission characteristics, with minimum threshold field (required to draw a current density ~ 1 μA/cm2) as compared to ZnO needles on silicon and virgin diamond films. The better emission characteristic of ZnO nanoneedles on diamond film is attributed to the high field-enhancement factor resulting due to the combined effect of the ZnO nanoneedles and diamond film. © 2009.


Samee M.A.,Osmania University | Awasthi A.M.,Consortium for Scientific Research | Shripathi T.,Consortium for Scientific Research | Bale S.,Osmania University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2011

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)Li2O-xNa2O-10K 2O-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. The glass stability is observed to be less which may be important for the present glasses as promising material for non-optical applications. We report, for the first time, the mixed alkali effect in the present glasses through optical properties. From the absorption edge studies, the values of indirect optical band gap (Eopt), direct optical band gap and Urbach energy (ΔE) have been evaluated. The values of Eopt and ΔE show non-linear behavior with compositional parameter showing the mixed alkali effect. The average electronic polarizability of oxide ions αO2-, optical basicity Λ, and Yamashita-Kurosawa's interaction parameter A 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 Li2O-Na2O-K 2O-B2O3 glasses are classified as normal ionic (basic) oxides. © 2010 Elsevier B.V. All rights reserved.


Edukondalu A.,Osmania University | Purnima M.,Osmania University | Srinivasy C.,Osmania University | Sripathi T.,Consortium for Scientific Research | And 3 more authors.
Journal of Non-Crystalline Solids | Year: 2012

Glasses with composition xLi 2O-(30 - x)Na 2O-10WO 3-60B 2O 3 (where x = 0, 5, 10, 15, 20, 25 and 30 mol%) have been prepared using the melt quenching technique. In the present work, the mixed alkali effect (MAE) has been investigated in the above glass system through density and modulated DSC studies. The density and glass transition temperature of the present gasses varies non-linearly, the exhibiting the mixed alkali effect. From the optical absorption studies, the values of direct optical band gap, indirect optical band gap energy (E o) and Urbach energy(ΔE) have been evaluated. The values of E o and ΔE vary non-linearly with composition parameter, showing the mixed alkali effect. The electronic polarizability of oxide ions, optical basicity and the Yamashita-Kurosawa's interaction parameter have been examined to check the correlation among them and bond character. Based on good correlation among electronic polarizability of oxide ions, optical basicity and the Yamashita-Kurosawa's interaction parameter, the present Li 2O-Na 2O-WO 3-B 2O 3 glasses were classified as normal ionic (basic) oxides. © 2012 Elsevier B.V. All rights reserved.


Edukondalu A.,Osmania University | Kavitha B.,Osmania University | Rahman S.,Osmania University | Gupta A.,Consortium for Scientific Research | Kumar K.S.,Osmania University
Optik | Year: 2015

Thickness dependencies of the optical properties of as-deposited amorphous 30Na2O-10WO3-60B2O3 prepared by electron beam evaporation on glass substrates at a base pressure of 9 × 10-7 Torr have been studied. Glancing angle X-ray diffraction studies were performed to confirm the amorphous nature of the prepared films. The absorption coefficient α, therefore extinction coefficient k, have been determined from the reflectance and transmission spectra at the strong absorption region. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple - DiDomenico model. The optical constants such as optical band gap, Urbach energy, the average excitation energy Eo and Ed the dispersion energy of thin films were determined. The optical data revealed the existence of allowed indirect transitions. © 2015 Elsevier GmbH. All rights reserved.


Srinivasu C.,Osmania University | Sathe V.,Consortium for Scientific Research | Awasthi A.M.,Consortium for Scientific Research | Rahman S.,Osmania University
Journal of Non-Crystalline Solids | Year: 2011

Bismuth based glasses containing LiF, Li2O and SrO were investigated by different physical, spectroscopic and transport techniques. The results show that density of the glass system increases whereas glass transition temperature decreases with increase in LiF content. The decrease in glass transition temperature is attributed to the entry of the fluoride ions into the glass network mainly substitutionally in place of oxygen ion. The increase in dc electrical conductivity in the present glasses with increase in the fluorine ions is due to the mixed contribution of the positively charged lithium cations throughout the glass network and the negatively charged fluorine, which may act as impurity and/or as terminal non-bridging halide ion. Infrared and Raman spectroscopic results indicate that the glass network consists of BiO 6 octahedral and BiO3 pyramidal units. © 2010 Elsevier B.V. All rights reserved.


Edukondalu A.,Osmania University | Sathe V.,Consortium for Scientific Research | Rahman S.,Osmania University | Siva Kumar K.,Osmania University
Physica B: Condensed Matter | Year: 2014

Mixed alkali borotungstate glasses with xLi2O-(30-x)Na 2O-10WO3-60B2O3 (0 ≤ x ≤ 30) composition were prepared by melt quench technique. The amorphous phase of the prepared glass samples was conformed from their X-ray diffraction and SEM studies. Differential scanning calorimetry and Raman spectroscopic studies were employed to investigate the structure of all the prepared glasses. The elastic moduli and Debye temperature were calculated in terms of Makishima-Mackenzie model. Acting as complementary techniques, Raman measurement revealed that the network structure of the present glasses is mainly based on BO3 and BO4 units placed in different structural groups. Raman spectra confirms the presence of tungsten ions mainly as WO6 groups. In the present work, the mixed alkali effect (MAE) has been investigated in the above glass system through modulated DSC studies. © 2014 Elsevier B.V.

Loading Consortium for Scientific Research collaborators
Loading Consortium for Scientific Research collaborators