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  • Author or Editor: K. Roy x
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Abstract

Polycrystalline ceramic samples of Bi2Sn2−xTixO7 (x = 0.0, 0.2, 0.4, 0.6, 0.8) have been synthesized by conventional solid-state reaction method. The effect of homovalent cation (titanium) substitution on the Sn-site on the structural, morphological, electrical and thermal properties of the pure Bi2Sn2O7 ceramics have been studied by X-ray diffraction (XRD) followed by scanning electron microscopic techniques, dc conductivity and modulated differential scanning calorimetry. The XRD analysis carried out by performing the Rietveld refinement using the space group Fd3m indicates that the increase of titanium contents do not lead to any secondary phase. The grain size distributions of all the samples were investigated by SEM. It was found that the grain sizes are strongly influenced by the addition of titanium to the system. The frequency and temperature dependent dielectric studies have been carried out. The dc conductivity measurement was carried out for all the compounds and the activation energies were calculated using the relation σ = σ0 exp(−E a/kT). The modulated differential scanning calorimetry has been used to investigate the effect of substitution on the specific heat, heat flow and other thermal parameters of the compounds. The results are discussed in detail.

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Abstract  

Some new coordination polymers have been synthesized by combining adipyl bis-biuret and azelyl bis-biuret with metals of first transition series viz Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). They were characterized by elemental analysis, infrared and reflectance spectral and magnetic studies. A detailed thermal study was carried out and thermal stability compared. The results obtained have been discussed.

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Every geophysical exploration method has non-uniqueness/ambiguity due to which interpretation is often misleading. If two or more data sets that deal with different physical properties are interpreted jointly then the combined study reduces the ambiguities in either method significantly. For layered structures magnetotelluric and seismic method provide information about the conductivities, velocities and thicknesses of the layers, where the thicknesses are the common parameters of seismic and magnetotelluric models. Assuming that the conductivity and velocity discontinuities are identical, the joint inversion of the two methods can improve the reliability of the estimation of thicknesses. In this paper on synthetic data will be shown, that the joint inversion yields better layer parameters, than the individual magnetotelluric or seismic inversions. The joint inversion decrease the effect of the equivalence, which at the magnetotelluric inversion often leads to misconclusion.  As inversion technique the simulated annealing and the linearized inversion will be used. In the present work, attempt is made to study the seismic refraction and magnetotelluric data to delineate reliable subsurface information.

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Abstract  

95Tc has been produced through -particle activation of a natural niobium target. The carrier-free 95Tc radionuclide has been separated from the bulk target using tri-n-octylamine (TOA) diluted by cyclohexane as extracting agent and HCl, HNO3 as aqueous phase. Solid-liquid extraction has also been carried out with TOA impregnated Kieselguhr mineral acid system. Technetium-95 was recovered from the organic phase by stripping with 0.1M EDTA above pH 9.

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Abstract  

Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl) phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO2(NO3)2·2TBEP and Th(NO3)4·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency from 1,282 to 1,217 cm−1 indicating the strong complexation of P=O group with UO2 2+ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction has also been investigated.

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Abstract  

Solvent extraction of U(VI) with di-isodecyl phosphoric acid (DIDPA)/dodecane from nitric acid medium has been investigated for a wide range of experimental conditions. Effect of various parameters including nitric acid concentration, DIDPA concentration, temperature, stripping agents, and other impurities like rear earths, transition metal ion, boron, aluminum ion on U(VI) extraction has been studied. The species extracted in the organic phase is found to be UO2(NO3)(HA2)·H2A2 at lower acidity (<3.0 M HNO3). Increase in temperature lead to the decrease in extraction with the enthalpy change by ∆H = −16.27 kJ/mol. Enhancement in extraction of U(VI) from nitric acid medium was observed with the mixture of DIDPA and tri butyl phosphate (TBP). The stripping of U(VI) from organic phase (DIDPA–U(VI)/dodecane) with various reagents followed the order: 4 M H2SO4 > 5% (NH4)2CO3 > 8 M HCl > 8 M HNO3 > Water. High separation factors between U(VI) and impurities suggested that the use of DIDPA for purification of uranium from multi elements bearing solution.

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Abstract  

During the past decade, interest has increased in qualifying and quantifying the threat posed to the public by the illegal use of radionuclides. In order to take investigations beyond the laboratory bench into more realistic scenarios, environmental and safety considerations dictate that these studies be performed on stable and benign surrogates. This paper discusses some of these studies, specifically the use of cerium dioxide for actinide ceramics and calcium and natural strontium ceramics for those based on 90Sr.

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Scientometrics
Authors: K. C. Garg, B. M. Gupta, Tabassum Jamal, Santanu Roy and Suresh Kumar

Summary An analysis of 330 questionnaires received from project investigators funded by AICTE indicates that project investigators preferred to present their research results at conferences rather than in national and international journals. Impact of funding has been better on human resource capability development as compared to research and technological output. Analysis of data using data envelopment analysis indicates that projects funded under electronics and communication engineering, mechanical engineering, electrical engineering and management displayed some consistency and uniformity with regard to impact on various output parameters.

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