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Your search keyword '"Sahu, P. Ch."' showing total 178 results
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178 results on '"Sahu, P. Ch."'

1. An Automated Laboratory Laser Heating Arrangement for Materials Synthesis at High Temperatures and High Pressures

Author

Subramanian, N., Ummru, Mrithula, Bindu, R., Kumar, N. R. Sanjay, Sekar, M., Shekar, N. V. Chandra, and Sahu, P. Ch.

Subjects
Physics - Instrumentation and Detectors, Physics - Geophysics
Abstract

This paper describes the automation of a laser heating arrangement for synthesizing and studying materials at high pressures (up to ~ 1 Mbar) and high temperatures (up to ~ 5000 K). In this arrangement, a diamond anvil high-pressure cell (DAC) containing a microscopic sample of typical diameter ~50-100 micrometer, is mounted on a precision X-Y nanomotor stage that forms part of an IR laser heating optical assembly. Automation of this stage has been accomplished using a LabVIEW virtual instrument program to manipulate the X and Y stages using nanopositioning systems. This has a major feature of enabling a rastered heating of the sample over a user-defined circular area, without any operator intervention in addition to a virtual joystick to position the sample with respect to the laser spot. This auto-rastering feature has the advantage of offering uniform exposure of a circular area of the sample to the incident heating laser beam apart from drastic reduction in scan time compared to a manual scan. The diameter of the circle can be varied from a maximum of ~24 mm down to the focal spot size of the laser (~few micrometers), enabling thereby usage of the laser heating arrangement for heating microscopic samples under high-pressure in a DAC, as well as bulk samples at atmospheric pressure. Examples for both macro and micro scale automated laser-heating experiments have been presented. In particular, at the micro scale, auto-raster heated carbon samples at ~ 17 GPa and ~2000 K showed excellent signatures of diamond formation compared to manually raster heated samples, highlighting the unique advantage of auto-raster heating., Comment: 16 pages, 4 figures, prepared for submitting to appropriate journal

Published
2008

20. Crystal structure of solid C70

Author

Valsakumar, M C, Subramanian, N, Yousuf, M, Sahu, P Ch, Hariharan, Y, Bharathi, A, Sankara Sastry, V, Janaki, J, Rao, G V N, Radhakrishnan, T S, and Sundar, C S

Published
1993
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22. High pressure structural behavior of YGa2: A combined experimental and theoretical study

Author

M, Sekar, N V, Chandra Shekar, R, Babu, Sahu, P Ch, Sinha, A K, Upadhyay, A, Singh, M N, K, Ramesh Babu, S, Appalakondaiah, Vaitheeswaran, G, V, Kanchana, M, Sekar, N V, Chandra Shekar, R, Babu, Sahu, P Ch, Sinha, A K, Upadhyay, A, Singh, M N, K, Ramesh Babu, S, Appalakondaiah, Vaitheeswaran, G, and V, Kanchana

Abstract

High pressure structural stability studies were carried out on YGa2 (AlB2 type structure at NTP, space group P6/mmm) up to a pressure of ~35 GPa using both laboratory based rotating anode and synchrotron X-ray sources. An isostructural transition with reduced c/a ratio, was observed at ~6 GPa and above ~17.5 GPa, the compound transformed to orthorhombic structure. Bulk modulus B0 for the parent and high pressure phases were estimated using Birch–Murnaghan and modified Birch–Murnaghan equation of state. Electronic structure calculations based on projector augmented wave method confirms the experimentally observed two high pressure structural transitions. The calculations also reveal that the ‘Ga’ networks remains as two dimensional in the high pressure isostructural phase, whereas the orthorhombic phase involves three dimensional networks of ‘Ga’ atoms interconnected by strong covalent bonds.

Published
2015

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