http://nopr.niscair.res.in/handle/123456789/1605 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/7596 Title: Superconductivity in Mg_1-xM_xB₂ (M = Cu and Ag) system <br/> <br/>Authors: Singh, Kiran; Mohan, Rajneesh; Shelke, Vilas; Gaur, N K; Singh, R K <br/> <br/>Abstract: The polycrystalline samples with nominal compositions Mg_1-xM_xB₂ (M = Cu, Ag; x = 0, 0.05) have been synthesized through solid-state reaction method. All the samples were synthesized from the stoichiometric mixtures of Mg, B, Cu and Ag. The samples were sintered at 850°C for 2 h in the presence of high purity argon flow. The X-ray diffraction (XRD), <i style="">R-T</i> measurement and scanning electron microscopy (SEM) techniques have been used for the characterization of samples for phase formation, superconducting transition temperature (<i style="">T</i>_c) and microstructure, respectively. It is noticed from the XRD patterns that the Cu and Ag doping leads to the formation of Mg-Cu and Mg-Ag alloys as the secondary phase, respectively along with the major phase of MgB₂. In case of Cu doping <i style="">T</i>_c decreases slightly and Ag doping has no effect on it. The grain size remains the same with these dopings, but the grain connectivity improves. <br/> <br/>Page(s): 420-422 Thu, 29 May 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1641 Title: Low temperature properties of La₂/₃Ba₁/₃MnO₃ perovskite manganite <br/> <br/>Authors: Gaur, N K; Srivastava, Archana <br/> <br/>Abstract: The evolution of cohesive and thermal properties of La₂/₃Ba₁/₃MnO₃ perovskite manganite was studied as a function of temperature (1K ≤ T ≤ 10K) by means of Rigid Ion Model (RIM). The heat capacity as a function of temperature computed from this model are, generally, in good agreement with their available experimental data measured with relaxation calorimetry technique. In addition, the results on the cohesive energy (φ), molecular force constant (f), Restrahalen frequency (ν〭), Debye temperature (QD) and Gruneisen parameter (ϒ) are also reported. <br/> <br/>Page(s): 451-453 Thu, 29 May 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1640 Title: Specific heat studies of hexagonal manganites RMnO₃ (Y, Sc, Lu) at low temperature <br/> <br/>Authors: Kaur, Nupinderjeet; Mohan, Rajneesh; Gaur, N K; Singh, R K <br/> <br/>Page(s): 447-450 Thu, 29 May 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1639 Title: High-pressure study of Na: A mean-field potential approach <br/> <br/>Authors: Bhatt, N K; Vyas, P R; Gohel, V B; Jani, A R <br/> <br/>Abstract: Study of anharmonicity through Grüneisen parameter is carried out for elemental Na at finite temperatures and pressures. The mean-field potential (MFP) approach has been employed in conjunction with the local pseudopotential to evaluate Helmholtz free energy at elevated temperatures and pressures. The calculated pressure and temperature variation of thermodynamic Grüneisen parameter (ϒth), pressure dependence of isothermal bulk modulus (BT) and total free energy at T = 300-K have been calculated. Results obtained are satisfactorily compared with the experimental and other first principles data. <br/> <br/>Page(s): 443-44 Thu, 29 May 2008 22:58:59 GMT