Search

Your search keyword '"Gupta, S. K."' showing total 2 results
2 results on '"Gupta, S. K."'

1. Crystallographic site swapping of La3+ ion in BaA' LaTeO6 (A' = Na, K, Rb) double perovskite type compounds: diffraction and photoluminescence evidence for the site swapping.

Author

Phatak, R., Gupta, S. K., Krishnan, K., Sali, S. K., Godbole, S. V., and Das, A.

Subjects
*PEROVSKITE, *CHEMICAL synthesis, *CRYSTAL structure, *X-ray diffraction, *NEUTRON diffraction, *CRYSTALLIZATION, *SODIUM compounds
Abstract

Double perovskite type compounds of the formula BaA'LaTeO6 (A' = Na, K, Rb) were synthesized by solid state route and their crystal structures were determined by Rietveld analysis using powder X-ray diffraction and neutron diffraction data. Na compound crystallizes in the monoclinic system with P21/n space group whereas, K and Rb compounds crystallize in Fm3m space group. All the three compounds show rock salt type ordering at B site. Crystal structure analysis shows that La ion occupies A site in Na compound whereas, it occupies B site in K and Rb compounds according to the general formula of AA'BB'O6 for a double perovskite type compound. Effect of this crystallographic site swapping of the La ion was also observed in the photoluminescence study by doping Eu3+ in La3+ site. The large decrease in the intensity of the electric dipole (5D0-7F2) transition in the Rb compound compared to the Na compound indicates that Eu3+ ion resides in the centrosymmetric octahedral environment in the Rb compound. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

2. Chemiresistive gas sensing characteristics of cobalt oxide thin films.

Author

Balouria, Vishal, Kumar, Arvind, Samanta, S., Bhattacharya, S., Singh, A., Debnath, A. K., Mahajan, Aman, Bedi, R. K., Aswal, D. K., and Gupta, S. K.

Subjects
GAS detectors, COBALT oxides, THIN films, ELECTRON beams, SUBSTRATES (Materials science), X-ray diffraction, SCANNING electron microscopy, CHEMICAL synthesis
Abstract

We report synthesis of 100 nm thick cobalt oxide films - prepared by electron-beam evaporation of Co onto quartz (Q- films) and c-plane sapphire substrate (S- films) followed by oxygen annealing. Films have been characterized for their structure and morphology by using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The prepared films have been investigated for their chemiresistive gas sensing characteristics for a host of test gases (CH4, CO, NO2, Cl2, NH3 and H2S) as a function of operating temperature (between 50 and 350°C) and gas concentration (3-30 ppm). We demonstrate that both Q and S-films are highly selective to H2S at an operating temperature of 250°C. However it has been observed that films prepared on sapphire show much less base resistance drift as compared to the films on quartz substrate. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results