R. K. Singh

Indian Institute of Science Education and Research Mohali

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Dinesh Varshney

Devi Ahilya Vishwavidyalaya

N. K. Gaur

Barkatullah University

Rajneesh Mohan

SASTRA University

Vilas Shelke

Barkatullah University

K. K. Choudhary

Indian Army

Kiran Singh

Dr. B. R. Ambedkar National Institute of Technology Jalandhar

Shovit Bhattacharya

Bhabha Atomic Research Centre

Netram Kaurav

Sage (United Kingdom)

Sadhna Singh

Barkatullah University

Nupinderjeet Kaur

Brno University of Technology

Cooperative Institutions

Barkatullah University

Devi Ahilya Vishwavidyalaya

Bhabha Atomic Research Centre

UGC DAE Consortium for Scientific Research

Institute of Physics, Bhubaneshwar

Homi Bhabha National Institute

Indian Institute of Technology Delhi

Indian Institute of Technology Indore

Solid State Physics Laboratory

CSIR National Physical Laboratory of India

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High-pressure phase transitions inCuxAg1−

Physical review. B, Condensed matter (1992)

Dinesh C. Gupta R. K. Singh

The high-pressure phase transitions in ${\mathrm{Cu}}_{\mathit{x}}$${\mathrm{Ag}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$I mixed crystals have been investigated theoretically by means of a three-body-potential model, which takes proper account of the Cauchy discrepancy and the charge-transfer effects in terms of three-body interactions. We have found that the values of the transition pressures (${\mathit{P}}_{\mathit{t}}$) increase slowly up to the concentrations x\ensuremath{\le}0.5 and remain close to the values of ${\mathit{P}}_{\mathit{t}}$ for AgI, while there is a rapid increase in ${\mathit{P}}_{\mathit{t}}$ at x>0.5. The slow increase of ${\mathit{P}}_{\mathit{t}}$ at x\ensuremath{\le}0.5 shows the dominance of the zinc-blende phase of AgI over that of CuI, indicating the persistence of a polytype structure in ${\mathrm{Cu}}_{\mathit{x}}$${\mathrm{Ag}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$I mixed crystals at these concentrations.

10.1103/physrevb.45.7031

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Citations (7)

Influence of temperature on elastic properties of caesium cyanide

physica status solidi (b) (2007)

Preeti Singh N. K. Gaur R. K. Singh

Abstract An extended three body force shell model (ETSM), which incorporates the effects of translational–rotational (TR) coupling, three body interactions (TBI) and anharmonicity, has been applied to investigate the temperature dependence of the second order elastic constants ( c ij , i , j = 1, 2) of CsCN. The elastic constant c 44 obtained by us shows an anomalous behaviour with the variation of temperature. The variations of elastic constants ( c 11 , c 12 , c 44 ) with temperature are almost in excellent agreement with Brillouin scattering measured data. We have also evaluated the temperature variations of the third order elastic constants ( c ijk ) and the pressure derivatives of the c ij in the CsCN material. However, their values could not be compared due to lack of experimental data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Caesium

Coupling constant

10.1002/pssb.200642463

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Citations (9)

Pressure induced phase transitions in some diluted magnetic semiconductors. I: Cd_1−xMnxTe

Phase Transitions (1993)

R. K. Singh Anita Arora

Abstract We have analysed the pressure induced phase transition from zincblende (B3) to rocksalt (B1) structure, and associated volume collapses, in the diluted magnetic semiconductors Cd1–x Mn x Te (0 ≤ x ≤ 0.6) using the three-body potential (TBP) approach developed by Singh and coworkers (Phase Transitions, 1989, 15, 127–134). In this approach the Gibbs free energy is expressed as a function of the three-body and van der Walls interactions and the pressure at T = O K. The phase transition (B3→B1) pressures (Pt ) and associated volume collapses, −ΔV(Pt )/V(0), computed by us, for the first time, from the TBP approach are in reasonably good agreement with their experimental values determined from the energy-dispersive X-ray and electrical resistivity measurements. We have also obtained satisfactory prediction of the observed linear decrease of the phase-transition pressures with concentration (x) in Cd1– x Mn x Te.

Magnetic semiconductor

10.1080/01411599308200314

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Citations (7)

Journal of Superconductivity (2002)

Dinesh Varshney K. K. Choudhary R. K. Singh

Atmospheric temperature range

10.1023/a:1021282721720

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An intralayer pairing mechanism for the coexistence of charge- and spin-density waves induced superconductivity in LaSrCuO

Superconductor Science and Technology (2002)

Dinesh Varshney G S Patel R. K. Singh

Starting from an effective two-dimensional dynamic interaction that includes screening of holes as carriers by charge density fluctuations and by optical phonons, we investigate the nature of a d-wave pairing mechanism leading to superconductivity in layered La-based cuprates. We consider the La–Sr–CuO system as an ionic solid containing layers of holes as carriers with a single CuO2 layer in a unit cell, where the localized spins form an antiferromagnetic (AF) order. The electron–phonon interaction matrix element in the case of an ordinary unit cell without the local AF order yields s-wave superconductivity. While for the unit cell with AF order, the wave-vector dependence of the intralayer effective interaction potential shows the sign reversal to create d-wave pairing due to localized antiferromagnetic spin order for the screened phonons. Following the strong coupling theory, the superconducting transition temperature, the isotope exponent, coherence length and magnetic penetration depth are also estimated. The implications of the intralayer pairing model and its analysis are discussed.

10.1088/0953-2048/15/11/323

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Citations (10)

Calcium and oxygen doping in Y Ba2Cu3Oy

Solid State Communications (2007)

Rajneesh Mohan Kiran Singh Nupinderjeet Kaur Shovit Bhattacharya Manglesh Dixit

Transition temperature

Calcium titanate

10.1016/j.ssc.2006.12.031

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Citations (14)

Temperature dependence of the phonon dynamics of CD4 in plastic phase

Il Nuovo Cimento D (1988)

R. K. Singh Nirmit Prabhakar

Debye model

Dynamics

10.1007/bf02450199

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Synthesis of Hg-added Bi2212 superconductors using various routes

Superconductor Science and Technology (1997)

Vilas Shelke R. K. Singh

We have studied the effect of Hg addition in the BiSrCaCuO system. Polycrystalline samples with nominal compositions and (x = 0.3) were synthesized in an open atmosphere by three different synthesis routes, i.e. solid-state reaction, matrix method and double-matrix method. The samples were characterized through XRD, R - T measurement and SEM. The phase ultimately obtained was mainly Bi2212. Almost identical depressions were observed in all the samples as a consequence of overdoping of charge carriers due to the high-oxygen ambient provided by HgO decomposition. Additional air annealing was found to be useful in attaining proper tuning of charge carriers, while quenching to room temperature had an adverse effect. Improvement in grain boundary linkage was observed for additionally annealed samples.

Charge carrier

Matrix (chemical analysis)

10.1088/0953-2048/10/1/009

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Citations (5)

Journal of Superconductivity (2002)

E.G. Rini N. K. Gaur Vilas Shelke Jyotsna Galgale M. P. Verma

Debye model

Debye–Hückel equation

Atmospheric temperature range

Debye

Specific heat