Superconducting Properties of Sm and Nd Substituted BPSCCO-2212 System
Systematic substitutional studies in Bi1.7 Pb0.3 Sr2 Ca1-x REx Cu2 Oy (RE = Sm, Nd and 0.0 ≤ x ≤ 1.0) system were carried out in order to determine the effect of the magnetic moment and ionic radius of the rare-earth ion on the Tc suppression rate. The single phase nature was maintained for both the systems throughout the substitutional region. In both these tetragonal structured compounds, a-parameter increased and c-parameter decreased as the dopant concentration increased. The oxygen content was found to increase with increasing Sm/Nd concentration, increase being more for the Nd doped samples. Resistivity studies have shown that the samples exhibited metallic nature at lower concentrations of rare earth before becoming semiconducting. The resistivity results have also shown that Tc (onset)’s are more for Sm substituted samples when compared to Nd substituted ones. The hole carrier concentration was found to decrease with rare earth ion substitution. DC magnetization measurements have indicated a decrease in superconducting volume with x for both Sm and Nd doped samples. For the same composition x, the superconducting volumes were found to be less in Nd doped samples. The results have shown that substitution of Ca by Sm /Nd probably brings about changes in the hole carrier concentration, the change being more for Nd. Consequently the Tc suppression rate and decrease in superconducting volume were more for Nd substituted ones suggesting that the magnetic moment of the rare-earth ion plays an important role in addition to its valency state.
KeywordsIonic Radius Hole Concentration Superconducting Property Excess Oxygen Insulator Transition
Unable to display preview. Download preview PDF.
- 2.Y. Yaroslavsky, M. Schieber, V. Beilin, S. Litvin, V. Burtman, V. Cinodman and D. Shaltiel Physica C 209 (1993) 179.Google Scholar
- 3.S.K. Agarwal, V.N. Murthy, G.L. Bhalla, V.P.S. Awana and A.V. Narlikar; Indian Journal of Pure and Applied Phys., 30 (1992) 586.Google Scholar
- 5.H.W. Zandbergen, W.A. Groen, A. Smit and G. Van Tendeloo; Physica C 168 (1990) 426.Google Scholar
- 8.A.Q. Pham, N. Merrien, A. Maignan, F. Stude, C. Michel and B. Raveau; Physica C 210 (1993) 350.Google Scholar
- 9.C.S. Gopinath, S. Subramanian, P. Sumana Prabhu, M.S. Ramachander Rao and G.V. Subba Rao Physica C 218 (1993) 117.Google Scholar
- 11.S. Satyavathi, M. Muralidhar, K. Nanda Kishore, V. Hari Babu, O. Pena, M. Sergent and F. Beriere J.Appl.Superconductivity (1995) (In Press).Google Scholar
- 12.K. Nanda Kishore, M. Muralidhar, V. Hari Babu, O. Pena, M. Sergent and F. Beriere; Physica C 204 (1993) 299.Google Scholar
- 13.S. Satyavathi et al. (to be communicated) (1995).Google Scholar
- 15.N.F. Mott, Metal Insulator Transitions (Taylor and Francis, London, 1974), and references thereinGoogle Scholar