http://nopr.niscair.res.in/handle/123456789/5947 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/5971 Title: Effect of Ga and Zn doping on coherent transition of YBCO superconductor <br/> <br/>Authors: Mohanta, A; Behera, D <br/> <br/>Abstract: The simultaneous incorporation of Ga³⁺and Zn²⁺to the Cu-site of YBa₂Cu₃O₇_-δ has been analyzed for microstructural and electrical properties. Temperature-dependent electrical resistivity, X-ray diffraction and SEM analysis of a set of YBa₂(Cu_0.95Zn_0.05_-xGa_x)₃O₇_-y films prepared by solid state reaction technique have been investigated to study the substitutional effects of Ga and Zn at chain and plane site of Cu, respectively. The redistribution of charges in the superconducting system due to oxygen content and the resistance of the weak-links related inhomogeneities give rise to <i>T</i>_{c<i> </i>}degradation and dual values of exponents in the <i>T</i>_c0 region. The exponent values for fluctuation conductivity in the <i>T</i>_c0 region decrease with increase of substitution concentration. The dual exponent character shows that the intergranular weak links develop more resistance with increasing impurities. <br/> <br/>Page(s): 676-680 http://nopr.niscair.res.in/handle/123456789/5970 Title: Electrical and optical properties of poly(aniline-co-8-anilino-1-napthalene sulphonic acid) — A material for ESD applications <br/> <br/>Authors: Bansal, Vineet; Bhandari, Hema; Bansal, M C; Dhawan, S K <br/> <br/>Abstract: The homopolymer of aniline (An) and its copolymer with 8-anilino-1-napthalene suplhonic acid (8-ANSA) was synthesized by chemical oxidative as well as electrochemical polymerization process in the presence of <i style="">para</i>-toluene sulphonic acid (PTSA) as a dopant. The spectral, thermal, morphological and electrochemical properties of PTSA doped polyaniline and its copolymer (An-co-8-ANSA) were studied and compared to elucidate the effect of the inclusion of 8-ANSA in the copolymer feed. The resultant copolymer showed better solubility and processibility but this approach usually results in the lowering of conductivity, hence the ratio of aniline and 8-ANSA in the copolymer feed was selected to 80:20. The room temperature conductivity of the PTSA doped polyaniline (PANI-PTS) and poly(An-co-8-ANSA) in 80:20 was found to be in the order of 1.74 S/cm to 9.77×10^-1S/cm, respectively. Conductivity mechanism of charge transport has been investigated in the range 30-300K. In the temperature range 30-70 K, copolymer showed tunneling mechanism. However, above 70 K conductivity attributes to Mott^’s variable range hopping (VRH) mechanism. The electrochemical behaviour of the polymers was studied by cyclic voltametry. The structure of the copolymer is characterized by ¹H NMR spectroscopy, UV-visible and FTIR spectroscopy. Electrostatic charge dissipation (ESD) of the conducting copolymer blend was also studied by blending of 1% of PTSA doped polyaniline and poly(aniline-co-8-ANSA) with LDPE which shows a static decay time of 0.1 to 0.25 sec on dissipating the charge from 5000 to 500 V. <br/> <br/>Page(s): 667-675 http://nopr.niscair.res.in/handle/123456789/5969 Title: Pressure-volume relationships and bulk modulus for sodium halides <br/> <br/>Authors: Kushwah, S S; Bhardwaj, N K <br/> <br/>Abstract: Equation of state for solids developed by Kushwah <i>et al. </i>[<i>Physica B</i>, 388 (2007) 20] has been used here to determine the pressure-volume relationships, bulk modulus and its pressure derivatives for NaF, NaCl, NaBr and NaI solids. The results are found to present close agreement with the experimental data. The results for <i>P, K</i> and d<i>K</i>/d<i>P</i> at different compressions have been used to study the relationship between d<i>K</i>/d<i>P</i> and <i>P</i>/<i>K</i>. <br/> <br/>Page(s): 663-666 http://nopr.niscair.res.in/handle/123456789/5968 Title: Fractional quantum Hall effect in graphene <br/> <br/>Authors: Sahoo, S; Das, S <br/> <br/>Abstract: The electrons in most of the conductors can be described by non-relativistic quantum mechanics but the electrons in graphene behave as massless relativistic particles, called Dirac fermions, though their speed is given by the Fermi velocity. The relativistic nature of the energy dispersion relation of electrons in graphene modifies the inter electron interactions. This results in the observation of a number of peculiar properties e.g. anomalous quantum Hall effect. We study the fractional quantum Hall effect (FQHE) in graphene. The quantized Hall conductivity in graphene in FQHE is shown to be: <img src='/image/spc_char/pap_eq1.gif'>,   where <i style="">n</i> = 0, 1, 2, 3 … This fascinating result shows that the FQHE in graphene has a sequence of states which is different from the sequence found in the 2D electron gas. <br/> <br/>Page(s): 658-662