Sintering characteristics of pyrophorically generated Y-Ba-Cu-O superconductor powders under vacuum

摘要

The discovery of high temperature ceramic superconducting (HTCS) materials has opened new vistas for potential applications. Among these HTCS materials Y-Ba-Cu-0 (YBCO) has a single super-conducting phase YBa2Cu30x (123) with a critical transition temperature (Tc) at 92 K. The superconducting properties of these materials (bulk) are affected by porosity [1] and by the weak link nature of the grain boundaries [2]. Although better densified bodies can be fabricated by hot isostatic pressing (HIP) [3] and by liquid phase sintering [4], decomposition of YBCO during HIPing and the presence of impurity phases in liquid phase sintered bodies affect the superconducting properties. Hence, these materials need to be fabricated by the pressureless solid state sintering process, which, however, also suffers limitations due to the existence of high vapour pressure of Ba and Cu above 1173 K [5,6]. Therefore minimization of sintering variables (temperature and time) has great importance in achieving better superconducting specimens. Optimization of sintering time and temperature for the YBCO powder compacts using vacuum sintering is discussed in this letter.