Search Results

Now showing 1 - 5 of 5

Hisslers observed during daytime in a low latitude ground station
(2009) Krishna Kumar Singh; Ravindra Pratap Patel; Balraj Kumar; Mohamad Altaf; Prince Ahmad Ganai; Abhay Kumar Singh; Ram Pal Singh; Lalmani
The observation of hisslers during daytime at low latitude station Jammu, India, is reported. The hissler elements are quasi-periodic falling tones observed during the period of hiss activity and appear in minutelong sequences with average spacing between individual elements of the order of 0.15 s. Hissler elements exhibit almost no dispersion and no complex internal structure in slope and intensity, and successive hissler elements do not overlap in time. It seems that the reported hisslers might have propagated in prolongitudinal mode. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2009.
Composition dependence of UV-visible and MID-FTIR properties of Se98-xZn2Inx (x = 0, 2, 4, 6 and 10) chalcogenide glasses
(2009) Abhay Kumar Singh; Kedar Singh
The UV-VIS absorption spectra of thin film of Se98-xZn2Inx (x = 0, 2, 4, 6 and 10) chalcogenide glasses were measured in the wavelength range of 200-1100 nm by using spectrophotometer. It is observed from UV-VIS absorption measurements that the optical energy gap (Eg) decreases with In content and it found a minimum for the Se92Zn2In6 system. The refractive index (n), extinction coefficient (k), real dielectric constant (') imaginary dielectric constant (''), absorption coefficient () are evaluated maximum for the Se92Zn2In6 composition. However, FTIR spectra were recorded in the wavenumber range 4000-400 cm-1. The FTIR recorded spectrum was shown to be a broad spectrum with increasing transmission in the MID (6-25 m) infrared region. The MID-IR spectrum transmittance percentage was also found to be considerably high for the Se92Zn2In6 system. © 2009 Taylor & Francis.
Crystallization kinetics and thermal stability of Se98-xZn 2Inx chalcogenide glasses
(2009) Abhay Kumar Singh; Kedar Singh
In this paper, we report on the non-isothermal crystallization kinetics of Se98-xZn2Inx (0≤ x≥ 10) chalcogenide glasses. The onset crystallization activation energy Ec, peak crystallization activation energy Ep and overall crystallization activation energy E have been determined by different approaches. The values of Ec, Ep and E have minima at a composition corresponding to 6 at% In. However the stability factor S and the crystallization rate constant stability factor K have a maximum and a minimum, respectively, at in the same composition. The nucleation and growth order parameter n, and the dimension order parameter m, are also determined and discussed for the present glasses. © 2009 Taylor & Francis.
Correlation between Meyer-Neldel rule and phase separation in Se98-xZn2Inx chalcogenide glasses
(2009) Abhay Kumar Singh; Neeraj Mehta; Kedar Singh
The present work reports the observation of Meyer-Neldel rule for the thermally activated crystallization of glassy Se98-xZn2Inx (0 ≤ x ≤ 10) alloys. We have observed a strong co-relation between the pre-exponential factor K0 of rate constant K(T) of crystallization and activation energy of crystallization Ec in the present case. This indicates the presence of compensation effect for the non-isothermal crystallization process in the present glassy system, which is explained in terms of phase separation of the present alloys due to flaw bonds of these amorphous solids. © 2008 Elsevier B.V. All rights reserved.
Optical and FTIR properties of Se93-XZn2Te5InX chalcogenide glasses
(2009) Abhay Kumar Singh; Neearj Mehta; Kedar Singh
In this work, we report the optical properties of bulk Se93-XZn2Te5InX (X=0, 2, 4, 6 and 10) chalcogenide glasses. Refractive index, extinction coefficient, real dielectric constant (ε′), imaginary dielectric constant (ε″), absorption coefficient (α) and energy band gap were obtained from analysis of common range (250-1100 nm) UV/Visible transmittance spectrum. Besides, transmission percentages were obtained from FTIR spectra in wave number range 4000-400 cm-1.The concentration dependence structural phenomena have been explained with help of average coordination 〈z〉. © 2009 Elsevier B.V. All rights reserved.

2009

Browse

Filters

Settings

Sort By

Results per page

Search Results