Growth and properties of (NEG)Ba2Cu3O7−δ processed under air
Résumé
According to recent studies, (Nd0.33Eu0.33Gd0.33)Ba2Cu3O7−δ (NEG123) material presents very attractive physical properties owing to an important fishtail effect. However, this three light rare earth (LRE=Nd, Eu and Gd) elements have ionic radius closed to the barium's one leading to the solid solution formation between the LRE and the Ba sites. These substitutions are detrimental for the superconducting properties and up to now, the synthesis under 1% of O2 in Ar is required to achieve interesting properties. In this work, it is shown that, using the Bridgman vertical configuration, single-domains of stoichiometric NEG123 with an optimal critical temperature of 94 K is obtained under air. Satisfying critical current density of 55 kA/cm2 is also measured at 77 K under self field and a fishtail effect can be observed at 2 T and 77 K.