Upadhyayula V Varadaraju

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Upadhyayula V Varadaraju
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Upadhyayula V Varadaraju
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Varadaraju, Upadhyayula V.
Varadaraju, Upadhyayula
Varadaraju, U. V.
Varadaraju, Upadhyayula Venkata
Varadaraju, Upadhayayula V.
Varadaraju, U.
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1987 - 19886
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Now showing 1 - 6 of 6
  • Placeholder Image
    Publication
    Superconductivity Studies on the High Tc Phase in the Y–Ba–Cu–O System
    (01-01-1987)
    Rao, G. V.Subba
    ;
    Upadhyayula V Varadaraju 
    ;
    Thomas, K. A.
    ;
    Vijayashree, R.
    ;
    Raju, N. P.
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    Srinivasan, R.
    ;
    De, U.
    ;
    Janaki, J.
    ;
    Radhakrishnan, T. S.
    Synthesis, characterization and superconducting behavior of the phases (i) Y2-xBaxCu2O5 (0\leqslantx\leqslant1.6) and (ii) YBa2Cu3CxO7Cy (0\leqslantx\leqslant2.0) are reported. The composition YBa2Cu4O7Cy shows a Tc (zero resistance) of 94K. © 1987 The Japan Society of Applied Physics.
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    Publication
    HIGH-T//c SUPERCONDUCTIVITY IN Ln//2// minus //xBa//xCu//2O//5 (1. 0 less than equivalent to x less than equivalent to 1. 6) AND LnBa//2Cu//3O//7 (Ln equals Dy, Er, Tm, Yb AND Y) COMPOUNDS.
    (01-12-1987)
    Subba Rao, G. V.
    ;
    Upadhyayula V Varadaraju 
    ;
    Vijayashree, R.
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    Padmanabhan, K.
    ;
    Balakrishnan, R.
    ;
    Mary, T. A.
    ;
    Raju, N. P.
    ;
    Srinivasan, R.
    ;
    De, U.
    ;
    Janaki, J.
    ;
    Radhakrishnan, T. S.
    Structure and T//c data on LnBa//2Cu//3O//7 (Ln equals Dy, Ho, Er, Tm, Yb and Y) compounds are reported and discussed. No reentrant behavior has been noted in these high-T//c superconductors for Ln equals Er and Yb until 4. 2 K. Four-probe resistivity was measured in the range 77-300 K employing ultrasonically soldered In-contacts. An inductance bridge with carrier-frequency amplifier was used to quickly check the samples for superconductivity at and above 77 K. A calibrated test set-up was employed to measure the superconductivity transition by the magnetic susceptibility technique.
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    Publication
    High-Tc superconductivity in Ln2-xBaxCu2O5 (1.0≤x≤1.6) and LnBa2Cu3O7 (Ln=Dy, Er, Tm, Yb and Y) compounds
    (01-01-1987)
    Rao, G. V.Subra
    ;
    Upadhyayula V Varadaraju 
    ;
    Vijayashree, R.
    ;
    Padmanabhan, K.
    ;
    Balakrishnan, R.
    ;
    Mary, T. A.
    ;
    Raju, N. P.
    ;
    Srinivasan, R.
    ;
    De, U.
    ;
    Janaki, J.
    ;
    Radhakrishnan, T. S.
    Structure and Tc data on LnBa2Cu3O7 (Ln=Dy, Ho, Er, Tm, Yb, and Y) compounds are reported and discussed. No reentrant behavior has been noted in these high-Tc superconductors for Ln=Er and Yb till 4.2 K. © 1987.
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    Publication
    Superconductivity studies on (Y1-xLnx)Ba2Cu3O7, Ln=La,Pr,Tb
    (01-01-1988)
    Natarajan, S.
    ;
    Chandrasekaran, K.
    ;
    Thomas, K. A.
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    Upadhyayula V Varadaraju 
    ;
    Subba Rao, G. V.
    ;
    Raju, N. P.
    ;
    Sankaranarayanan V 
    ;
    Srinivasan, R.
    Studies on the title compounds show that while La and Pr form complete solid solutions, Tb does not substitute for Y. Superconducting transition temperature (Tc) decreased with increasing x from 91K but pronounced effect is noted for Ln=Pr. PrBa2Cu3O7 exhibits a semiconductor behavior. © 1988 Elsevier Science Publishers B.V.
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    Publication
    Enhancement of thermopower in the high T c superconductor YBa2Cu3O7 and related compounds
    (01-08-1987)
    Srinivasan, R.
    ;
    Sankaranarayanan V 
    ;
    Raju, N. P.
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    Natarajan, S.
    ;
    Upadhyayula V Varadaraju 
    ;
    Subba Rao, G. V.
    The absolute thermopower of single phase YBa2Cu3O7 and Y0.8Er0.2Ba2Cu3O7 has been measured in the range 250 K to the superconducting transition temperature. It is found that these compounds show a large enhancement of thermopower in the range 150 K down to T c. This enhancement shows a steep exponential drop as the temperature increases from the transition temperature. The temperature variation of the enhancement is too steep to be accounted for by electron-phonon or electron-local structural excitation mechanisms. © 1987 Indian Academy of Sciences.
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    Publication
    Effect of chemical substitution on the high-Tc behavior of YBa2Cu3O7
    (01-01-1987)
    Upadhyayula V Varadaraju 
    ;
    Natarajan, S.
    ;
    Kumar, T. S.Sampath
    ;
    Paranthaman, M.
    ;
    Rao, G. V.Subba
    ;
    Raju, N. P.
    ;
    Srinivasan, R.
    The effect of chemical substitution on the high-Tc (91 K) superconducting oxide YBa2Cu3O7, with the distorted perovskite structure, has been studied. Subtle changes in Tc occur when Y is partly replaced by Dy, Ho, Er, Tm, Yb, Lu, Bi and In. The possibility of coexistence of magnetic order and superconductivity or reentrant behavior in these high-Tc compounds will be described and discussed. © 1987.