Environmental degradation of Bi-2212 highly textured rods

Resumen del trabajo presentado a la: "3rd International Conference on Superconductivity and Magnetism" celebrada en Estambul (Turquia) del 29 de abril al 4 de mayo de 2012.
The development of practical applications of high temperature superconductors requires not only the knowledge of their electrical properties, but their behaviour under different environments. Bulk Bi-2212 superconductors have demonstrated that they are suitable for many applications when they are properly processed, for example trough the laser floating zone technique. The Bi-2212 bulk materials textured by this technique have very interesting electrical properties that allow developing current leads and fault current limiters. One of the main advantages of this method is that samples can be rapidly grown due to the large thermal gradients present at the solid-liquid interface. On the other hand, for any practical application, it is necessary to take into account their reactivity to moisture and carbon dioxide, which leads to their chemical degradation as: Bi2Sr2CaCu2O8 + 3H2O -----> 2Sr(OH)2 + Ca(OH)2 + CuO + CuBi2O4 Sr(OH)2 + CO2 -----> SrCO3 + H2O Ca(OH)2 + CO2 -----> CaCO3 + H2O In this work, the environmental (water and saturated carbon dioxide water) susceptibility of Bi-2212 thin rods grown by laser floating zone method has been measured by means of electrical properties variation (critical current density and resistivity). Although the electrical properties did not change considerably it has been found a higher influence on the mechanical ones. It has been also found that the special microstructure developed in the growth process is responsible for this behaviour. On the other hand, this influence must be considered in practical applications in order to maintain the mechanical integrity of the system.