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Arya S.K.,ABES Institute of Technology | Singh K.,Thapar University
Journal of Thermal Analysis and Calorimetry

In the present investigation, the effects of titanium and vanadium concentration on the thermal properties have been studied for 30Li2O-55B2O3-5ZnO-xTiO2-(10-x)V2O5 (0 ≤ x ≤ 10) glasses. To understand the crystallization mechanics, activation energy has been calculated using two different approaches, i.e., Kissinger model and Augis and Bennett model. Using the derivative differential thermal analysis, the inflection point temperature (T f) and crystallization constants k y(T) and k f(T), for different heating rates, have also been obtained for all the glasses. Furthermore, kinetic parameters such as fluctuation free volume (f g) and change in bulk thermal expansion coefficient (α f) have been calculated for all the glass samples. The replacement of V2O5 by TiO2 induces phase separation in glasses. © 2015 Akadémiai Kiadó, Budapest, Hungary. Source

Gupta R.K.,Thapar University | Kumar V.,Indian Institute of Technology Roorkee | Srivastava V.K.,ABES Institute of Technology
International Journal of Chemical Reactor Engineering

This work aims at compiling the important works on the modeling of a fluid catalytic cracking (FCC) riser reactor. The modeling of a riser reactor is very complex due to complex hydrodynamics and unknown multiple reactions, coupled with mass transfer resistance, heat transfer resistance and deactivation kinetics. A complete model of the riser reactor should include all the important physical phenomena and detailed reaction kinetics. As the computational fluid dynamics (CFD) is emerging as a powerful tool for modeling the FCC riser, various works on riser modeling using CFD are also included in the paper. Copyright © 2010 The Berkeley Electronic Press. Source

Arya S.K.,ABES Institute of Technology | Danewalia S.S.,Thapar University | Singh K.,Thapar University
Journal of Materials Chemistry C

Glasses with composition B2O3-Li2O-ZnO-TiO2-V2O5 were prepared with a melt and quench technique with variable concentration of TiO2 and V2O5. Structural aspects of the as-prepared sample were explored with the help of electron paramagnetic resonance spectroscopy (EPR). Conductivity and dielectric properties of the glasses and nanocrystalline glass ceramic were investigated using impedance spectroscopy. Vanadium was present in these glasses in the V4+ state, however, in initial composition, it was in the V5+ state. The maximum quantity of TiO2 contained glasses formed a nanocrystalline rutile phase, which dominated the electronic conduction at lower temperatures with decreased activation energy, i.e. 0.21 eV. Moreover, the presence of a nanocrystalline TiO2 phase reduced the dielectric constant ∼3 at room temperature and 1 MHz with excellent stability over a wide temperature and frequency range. The present nanocrystalline glass ceramic and glasses can be used in fast communication devices. © 2016 The Royal Society of Chemistry. Source

Kaur G.,Virginia Polytechnic Institute and State University | Pickrell G.,Virginia Polytechnic Institute and State University | Kumar V.,Sri Guru Granth Sahib World University | Pandey O.P.,Thapar University | And 2 more authors.
Bulletin of Materials Science

In the present investigation, mechanical and spectroscopic properties of glass composites have been investigated. The glass composites have been prepared by the milling technique instead of using any filler particle. Due to the presence of different alkaline earth modifiers in composites, marked difference in their strength and optical properties is observed. The band gap, Urbach energy and the extinction coefficient of the glass composites have been calculated using UV-visible spectroscopy. Moreover, the real and imaginary dielectric constants have also been calculated for all the composites in addition to the Weibull statistics and cumulative probability of failure. The results have been discussed in light of comparison between the glass composites and the individual glasses. The mechanical and optical properties indicate marked effect on the mechanical strength, band gap and Urbach energy for glass composites as compared with the individual glasses. © Indian Academy of Sciences. Source

Arya S.K.,ABES Institute of Technology | Arya S.K.,Thapar University | Singh K.,Thapar University
Journal of Non-Crystalline Solids

The structural and optical properties have been investigated for the 30Li2O-55B2O3-5ZnO-xTiO2-(10 - x)V2O5, (0 ≤ x ≤ 10) glasses using different spectroscopic characterization techniques. The relationship between optical and structural properties has been established in light of the variation of TiO2 content. The band gap shows a decreasing trend with a decrease in V2O5 content. Physical parameters like density, molar volume, ionic concentration and inter ionic distance have been obtained for all the glass compositions. Theoretical parameters like optical basicity, oxide polarizability and electronegativity have been obtained and discussed in relation to the non-bridging oxygen (NBO). Bulk modulus has been calculated theoretically and correlated with average stretching force constant and network bonds/volume. © 2015 Elsevier B.V. All rights reserved. Source

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