R M Iyer
Articles written in Bulletin of Materials Science
Volume 11 Issue 4 December 1988 pp 269-275
K Govinda Rajan N V Chandra Shekar G V N Rao A J Singh R M Iyer
Gallium phosphide is a typical III–V compound semiconductor and is also an important electronic material. The synthesis and single crystal growth of this compound by melt methods is rendered very difficult because of the large phosphorus vapour pressure. A high pressure vessel with internal heating and a quartz reactor was first developed for the direct synthesis of gallium phosphide. The crystal growth was carried out in a second high pressure chamber rated for 100 bars gas pressure and equipped with the paraphernalia for crystal growth. Single crystals of gallium phosphide were grown from the polycrystalline starting material by the vertical Bridgman method and the vapour pressure problem was overcome by encapsulating the melt in a column of molten boric oxide. Both boron nitride and silica were employed as crucibles, and with the former, single crystal rods of 8–10 mm diameter and 10–15 mm length were obtained.
Volume 14 Issue 2 April 1991 pp 223-226 International Conference On Superconductivity—I
On the synthesis and structure of single-phase (Bi, Pb)2Ca2Sr2Cu3O10
P V P S S Sastry J V Yakhmi R M Iyer
We report an elegant method for the synthesis of single-phase Bi-2223 superconductor from a stoichiometric composition Bi1.7Pb0.3Ca2Sr2Cu3Oy by a matrix reaction route. The superconducting transition temperature
Volume 14 Issue 2 April 1991 pp 241-246 International Conference On Superconductivity—I
Synthesis of single phase Tl-2223 superconductors: How much thallium do we really need?
G M Phatak R M Iyer K Gangadharan R M Kadam P V P S S Sastry M D Sastry J V Yakhmi
This paper describes the synthesis and microwave absorption studies of single phase Tl-2223 compound, with
Volume 14 Issue 2 April 1991 pp 275-278 International Conference On Superconductivity—I
Effect of non-stoichiometry and Ce-doping on the tetragonal superconducting phase CaBaLaCu3O7−
I K Gopalakrishnan R Alfred Gunasekaran J V Yakhmi R M Iyer
We have synthesized CaBaLaCu3O7−
Volume 14 Issue 3 June 1991 pp 603-605 International Conference On Superconductivity—II
Inelastic neutron scattering from Tl2CaBa2Cu2O8
S L Chaplot B A Dasannacharya R Mukhopadhyay K R Rao P R Vijayaraghavan R M Iyer G M Phatak J V Yakhmi
Coherent inelastic neutron scattering measurements have been carried out on the high temperature superconductors Tl2CaBa2Cu2O8 (Tl-2122,
Volume 14 Issue 3 June 1991 pp 681-686 International Conference On Superconductivity—II
P K Pujari T Datta Satya Prakash S B Manohar I K Gopalakrishnan G M Phatak J V Yakhmi PVPSS Sastry R M Iyer
Doppler-broadened annihilation radiation spectra have been measured as a function of temperature from 77 K to 300 K, for several high temperature oxide superconductors viz single-phase YBCO, single- and mixed-phase Tl-Ca-Ba-Cu-O and Bi-Ca-Sr-Cu-O compounds. The temperature-dependent parameters extracted respond to a change at the onset of superconducting transition. The observations point to involvement of oxygen valence electrons at the onset of superconducting transition. Also a possible structural change and/or increase in electron density at the oxygen vacancy/defect sites seem to accompany the transition. In addition, the parameters derived are seen to be sensitive to the presence of more than one superconducting phases in mixed phase samples.
Volume 14 Issue 3 June 1991 pp 827-830 International Conference On Superconductivity—II
Thermoelectric power of single-phase samples of Tl2CaBa2Cu2O
V Vijayashree C K Subramaniam R Srinivasan I K Gopalakrishnan PVPSS Sastry J V Yakhmi R M Iyer
Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower of these samples was measured in the temperature range 250 K-
Volume 46, 2023
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Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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