Strong Dependence of Superconducting Transition Temperature (Tc) on the Rare Earth Ionic Size in REBaSrCu3O7 (RE=Y, Dy, Nd and La) Series
Abstract
The REBaSrCu3O7 compounds with RE=Y, Dy, Nd and La have been synthesized by the standard solid-state reaction route. Superconducting transition temperatures (Tc), as measured by ac susceptibility technique, are 81 K, 79 K, 62 K and 45 K for samples with RE=Y, Dy, Nd and La, respectively. The rare earth dependence of Tc in the REBaSrCu3O7 series is quite different from that observed in the REBa2Cu3O7 (RE:123) series where Tc is nearly independent of the choice of the RE (except when RE=Ce, Pr and Tb). Neutron diffraction studies have been carried out on the REBaSrCu3O7 compounds and structural details have been obtained from the Rietveld analysis of the room-temperature neutron diffraction data. The compounds with RE=Y, Dy are found to crystallize in the orthorhombic RE:123 structure (space group Pmmm) with orthorhombicity considerably smaller than that of the RE:123 compounds. In fact, the orthorhombicity reduces so much that the REBaSrCu3O7 compounds with light rare earths, RE=La and Nd, are tetragonal or almost tetragonal.
- Publication:
-
Modern Physics Letters B
- Pub Date:
- 2000
- DOI:
- 10.1142/S0217984900000471
- Bibcode:
- 2000MPLB...14..361A