Dubey V.,Bhilai Institute of Technology |
Dubey V.,National Institute of Technology Raipur |
Agrawal S.,National Institute of Technology Raipur |
Kaur J.,Government Vytpg Autonomous College
Optik | Year: 2015
The present paper reports the synthesis and characterization photoluminescence and thermolumi-nescence studies of Gd3+doped Y2O3phosphors. The effect of variable concentration of europium onphotoluminescence (PL) and thermoluminescence (TL) behavior are also studied. The samples were pre-pared by solid state synthesis technique which is suitable for large scale production of phosphors. Thestarting materials used for sample preparation are ZrO2and Gd2O3and CaF2used as a flux. The preparedsample was characterized by X-ray diffraction technique (XRD). The surface morphology of preparedphosphor was determined by field emission gun scanning electron microscopy (FEGSEM) technique. Thediffraction pattern was measured by transmission electron microscopy (TEM) with selected area diffrac-tion pattern. All prepared phosphor with variable concentration of Gd3+(0.2-2 mol%) was studied byphotoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broadexcitation centered at 249 and 254 nm with few shoulder weak peaks at 275, 308 and 315 nm. The exci-tation spectra with variable concentration of Gd3+show strong peaks at 613 nm for 254 nm excitation.For 275 nm excitation strong peaks found at 468, 567, 578 and 608 nm. For recording TL glow curve everytime 2 mg phosphor was irradiated by UV 254 nm source and fixed the heating rate at 6.7°C s-1. Sam-ple shows well resolved peak at 97°C for 2 mol% of Gd3+. Trapping parameters are calculated for everyrecorded glow curve. © 2014 Elsevier GmbH. All rights reserved.
Hou G.,Peking University |
Wang Y.,Peking University |
Hari K.R.,Government Vytpg Autonomous College
Journal of Geodynamics | Year: 2010
The transmission of the tectonic regime from the Paleo-Asian Ocean to the Pacific Ocean during Mesozoic era was reconstructed using the modeling of Late Triassic (T3) and Late Jurassic (J3) stress fields employing two dimensional linear finite element models (2-D FEM). The model at T3 proposes that Qinling-Dabie-Sulu orogens coevally collided and the model J3 proposes that Subei block continued to collide with the North China block along the Sulu orogen while the collision of the Qinling-Dabie orogen was terminated. The stress fields at T3 and J3 during the two episodes were calculated based on mechanical conditions under different deviatoric stresses acting along the boundaries of the North China craton by elastic finite modeling. The transmission between two episodes of stress fields resulted from Qinling-Dabie-Sulu collision between North China and South China in the Late Triassic period, and from continued collision between the Subei block and North China by the NW-trending movement of Izanagi plate during Late Jurassic. The results from modeling of the Mesozoic stress fields of the North China suggest that late Jurassic was the key transmission period of the tectonic regime of the North China block when large scale thrusting triggered the subsequent destruction of the North China craton. © 2009 Elsevier Ltd.
Sar S.K.,Bhilai Institute of Technology |
Rathod N.,Government Vytpg Autonomous College |
Pandey P.K.,Bhilai Institute of Technology
International Journal of Chemical Kinetics | Year: 2010
Pseudo-first-order rate constants for the nucleophilic debenzoylation reaction of ρ-nitrophenyl benzoate with, various hydroxamate ions [RC = ONHO -] were investigated in aqueous cationic micellar media at pH 7.8 and 27°C. The kinetic rate data of the reaction revealed that the nucleophilic reactivity sequence of these hydroxamate ions is generally benzohydroxamic acid > salicylhydroxamic acid > acetohydroxamic acid. The k obs value increases upon addition of cationic surfactants to the reaction medium involving interfacial ion exchange between bulk aqueous media and micellar pseudophase. The effect of surfactant head and tail group is discussed. © 2009 Wiley Periodicals, Inc.
Hari K.R.,Government Vytpg Autonomous College |
Chalapathi Rao N.V.,Banaras Hindu University |
Swarnkar V.,Government Vytpg Autonomous College
Journal of the Geological Society of India | Year: 2011
We report the occurrence of orthopyroxene gabbro from the Phenai Mata Igneous Complex (containing thoeliitic and alkaline rocks) that occur within Deccan Traps. The P-T calculations based on two pyroxene thermometry vary from 8.5±1.0 kbar and 963±39 °C. These gabbroic rocks exhibit high Mg# (0.67 to 0.71). But their primary magma signature can be negated due to their high SiO 2 (> 50 wt %), low Ni (32-35 ppm) and Cr (105-182 ppm) contents. Further, simple fractional crystallization was not responsible for the modification of the magma. Modeling carried out using trace element concentrations revealed that concurrent assimilation and fractional crystallization (AFC) was responsible for the genesis of these rocks. Small pods of magma could have accumulated in the crustal portions and concurrent assimilation and fractional crystallization have taken place in the generation of gabbro and orthopyroxene gabbro in the present study area. © 2011 Geological Society of India.
Tiwari A.,Government Vytpg Autonomous College |
Soni A.,Government Vytpg Autonomous College |
Bajpai A.K.,Government Model Science College
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry | Year: 2012
Phenol could be efficiently removed from polluted wastewater by using biopolymeric beads composed of nano-iron oxide and alginate. The polymeric beads were characterized by FTIR, SEM and XRD analysis techniques. The efficiency of the polymeric adsorbent was studied by measuring the maximum uptake of phenol using the batch technique. The batch kinetic and isotherm studies were carried out under varying experimental conditions such as contact time, temperature, initial phenol concentration, adsorbent dosage and pH. © 2012 Taylor amp; Francis Group, LLC.