TITLE:
Alkaline Earth (Ca) and Transition Metal (Ni) Doping on The Transport Properties Of Y1-Xcaxba2(Cu1-Yniy)3O7-δ Superconductors
AUTHORS:
Dinesh Varshney, Arvind Yogi, Neha Dodiya, Irfan Mansuri
KEYWORDS:
Y-Based Superconductors, Doping Effect, Transport Properties
JOURNAL NAME:
Journal of Modern Physics,
Vol.2 No.8,
August
12,
2011
ABSTRACT: 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.