B K DAS
Articles written in Bulletin of Materials Science
Volume 1 Issue 2 October 1979 pp 99-106 Research Communications
The oxidation kinetics of CuFeO2 in Cu-Fe-O system have been studied between temperature range 500° C and 900° C in an ambient atmosphere containing constant oxygen partial pressure in the flowing nitrogen. Thermogravimetric analysis (TGA) technique was used as the main tool. The oxidation rate was found to decrease and the activation energy calculated from the oxidation rate constants for various composition increased from 8 to 45 k cal/mole on increasing the Fe2O3 content in the system. The value of exponent
Volume 3 Issue 4 December 1981 pp 435-442
The sintering behaviour of lanthanum chromite with the addition of 1 to 3 wt% TiO2 was studied. Densification was examined as a function of sintering temperature and TiO2 concentration. The results showed that pure LaCrO3 could not be densified to >75% of the theoretical density, while the densities exceeding 90% of the theoretical were achieved with 3 wt% titania addition at 1600° C.
Metallographic study reveals a normal grain growth following the rate equation
Volume 5 Issue 1 March 1983 pp 33-38
Grain growth kinetics of ZnO ceramics containing 6% additives of Bi2O3, CoO and MnO in equal molar ratios has been studied in the temperature range 1000 to 1350°C. It has been observed that the grain growth data fits the
Volume 6 Issue 2 May 1984 pp 243-258 Electrical Properties And Electrochemistry
Polycrystalline silicon and zinc oxide ceramic are important electronic materials. The electrical properties which determine the applications of polycrystalline silicon in integrated circuits and solar cells and that of ZnO ceramic in varistors are due primarily to grain boundary effects in them. A large amount of information in this area has already been gathered in literature but the quantitative understanding of grain boundary effects in these materials is not yet complete. In this review the important aspects of grain boundaries and their effects on transport and photoelectric properties of polycrystalline silicon and on the I–V characteristic of ZnO varistors are discussed.
Volume 6 Issue 6 December 1984 pp 979-989
Beta alumina solid electrolyte is a potential candidate in the fabrication of Na-S batteries. In the present study, it has been prepared in the form of discs by uniaxially as well as isostatically pressing and sintering in the temperature range 1585–1630°C, the highest sintered density of 3·25 g/cm3 has been achieved in the samples isostatically pressed and sintered at 1630°C. X-ray analysis of the samples shows formation of
Volume 6 Issue 6 December 1984 pp 1092-1092 Erratum
Volume 14 Issue 2 April 1991 pp 377-379 International Conference On Superconductivity—I
We present an overview of our powder synthesis procedure and give some initial results concerning the superconducting properties of YBa2Cu3O7−
Volume 17 Issue 2 April 1994 pp 153-162
DC magnetization measurements have been carried out on bulk YBCO/Ag composites with silver content up to 20wt per cent. DC fields in the range 0·5 mT to 200 mT have been used to investigate the inter- and intragranular properties at 77K. The AC susceptibility as a function of temperature at different AC fields (0·026–0·30 mT) has also been studied. Under small DC fields (≈ 4 mT), depending on the Ag content and
Volume 18 Issue 8 December 1995 pp 989-996
Volume 18 Issue 8 December 1995 pp 1031-1034
Medium resolution magneto-optic Faraday rotation measurement setup has been reported. Measuremental setup reported is made up of simple polarized laser source, beam expander, analyzer and a bisected cross polarized
Volume 19 Issue 3 June 1996 pp 475-481
Yttrium iron garnet thin films have been prepared by low pressure metallo-organic chemical vapour deposition method (MOCVD). Dipivaloyl methanates of yttrium and iron have been used as the precursors in the MOCVD growth of the garnet films. Post deposition O2 annealing at 900°C is required to form a garnet phase which also shows orthoferrite and component Y2O3 and α-Fe2O3 phases. We show that a partial H2 reduction treatment minimizes secondary phases and stabilizes the garnet phase. These treatments also enhance the magnetic properties considerably.
Volume 22 Issue 3 May 1999 pp 353-362 Semiconductors, Photovoltaics And Optoelectronic Materials
A process simulator named “2D-DIFFUSE” has been developed where the coupled diffusion equation of dopant impurity and point defects: interstitials and vacancies, has been solved numerically in two-dimension. The interaction of point defects has been modeled assuming quasi (i.e. local) equilibrium,
Volume 39 Issue 7 December 2016 pp 1735-1743
In this article we report a chemical sol–gel approach to synthesize zinc oxide nanomaterials capped with ethylene diamine tetra acetic acid (EDTA), citric acid and oleic acid, and to study the effect of the surface modification on their photocatalytic activity and the kinetics for the degradation of Malachite Green (MG) dye. The structural, optical and chemical features were systematically characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared and UV–vis absorption spectroscopy. The objective of using the capping agents was to confine the size and control the growth and morphology of the nanomaterial. The smallest crystallite size was recorded as 29 nm for EDTA-capped rod-shaped ZnO. A comparison study of the effect of thethree different capping surfactants on ZnO nanomaterial for photocatalytic degradation ofMGdye under solar light showed that EDTA with higher denticity coordinated efficiently with the surface of ZnO nanocrystalline catalystsand hence demonstrated better decolouration of the dye under solar light. The dye degradation followed the psuedofirst-order kinetics. EDTA proved to be the best capping agent among all the three for ZnO nanomaterial.
Volume 42 | Issue 6
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