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Alkaline Earth (Ca) and Transition Metal (Ni) Doping on The Transport Properties Of Y<sub>1-X</sub>ca<sub>x</sub>ba<sub>2</sub>(Cu<sub>1-Y</sub>niy)<sub>3</sub>O<sub>7-δ</sub> Superconductors

Author(s): Dinesh Varshney | Arvind Yogi | Neha Dodiya | Irfan Mansuri

Journal: Journal of Modern Physics
ISSN 2153-1196

Volume: 02;
Issue: 08;
Start page: 922;
Date: 2011;
Original page

Keywords: Y-Based Superconductors | Doping Effect | Transport Properties

We report the results of dc resistivity, ac susceptibility, and thermopower study of partial substitution at Y (A site by Ca) and at Cu (B site by Ni) polycrystalline superconductors. The iodometric analysis reveals that the oxygen deficiency,δ,for YBa2Cu3O7-δ(S-I),Y0.9Ca0.1 Ba2Cu3O7-δ(S-II),Y0.8Ca0.2Ba2Cu3O7-δ(S-III) and Y0.9Ca0.1 Ba2(Cu0.99Ni0.01)3O7-δ(S-IV) samples are 0.16, 0.30, 0.39 and 0.29 respectively. The x-ray powder diffraction pattern indicates that all samples are in orthorhombic phase. The dc resistivity, ac susceptiblity and the thermopower measurements shows that the divalent Calcium doping at the trivalent Y site and transition metal Ni doping at Cu site causes a suppression of the superconducting transition temperature (Tc) from 89 to 81 K. The ac susceptibility confirms the ferromagnetic to antiferromagnetic phases at a defined Tc. The room temperature S value increases for Ca substituted YBa2Cu3O7-δwhile to that it decreases for Y0.9Ca0.1Ba2(Cu0.99Ni0.01)3O6.71. The above feature is an indicative of enhanced number of mobile holes for the Ca doped YBa2Cu3O7-δ, while to that the charge carrier density is reduced in simultaneous A (Ca) and B (Ni) site doped sample.

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