Improved Jc properties and microstructure in Na-doped MTG-YBCO crystals
Abstract:The effect of Na2C2O4 addition on the microstructure, magnetization and dc transport properties of melted-textured-growth (MTG) YBa2-xNaxCu3Oy + 40 mol% Y2BaCuO5 crystals with x 0, 0.1 and 0.2 has been investigated. X-ray diffraction patterns reveal that the length of the c-axis increases with increasing the Na-doped concentration and that these crystals are in single phase except for very weak peak of Y211. Composition analyses indicate the evidence of Na+ ion existing in the Na-doped samples and the part Y3+ or Ba2+ ion being replaced by Na+ ion. Magnetization curves at 77 K show an improved field dependence of the critical current density and a second peak around 0.8-1 T for Na-doped YBCO crystals. DC transport measurement gives a shift of the irreversibility line to lower temperatures and a larger anisotropy for the Na-doped YBCO crystal. The possible source of these behaviours were supposed to be connected with the certain inhomogeneous distribution of Na (different x) in MTG YB(Na)CO crystal, which leads to a distribution of different Tc clusters.
Document Type: Miscellaneous
Affiliations: 1: Department of Physics, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China 2: Shanghai Institute of Metallurgy, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China 3: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
Publication date: March 1, 2002