Critical currents and current-voltage characteristics of high temperature superconducting ceramics

Abstract

Abstract We discuss problems related to the “arrangement” and properties of those elements of the granular structure of HTSC ceramics (with an emphasis on the ceramics of the YBa2Cu3O composition) which define the critical currents and current-voltage characteristics of ceramic materials. The basis element of this sort are intergranular boundaries. In materials of practical interest their predominant role as “weak” sites (that is, areas with a low critical current density) is to lower critical current density of ceramics. For modeling purposes ceramics can be regarded as Josephson media, that is as sets of superconducting grains interconnected by Josephson Junctions. This model provides a means of describing a good number of properties of superconducting ceramics without going into detail about the specific genesis and “arrangement” of weak intergranular links. In this way we discuss the critical current and current-voltage characteristics of HTSC-ceramics and their dependencies on temperature, magnetic field and pressure.