Contacts for superconducting ceramics

Superconducting ceramics with transition temperatures over 77 K were tested with different types of contacts. The contacts were prepared by a number of methods from different metals and from conductive paint. The measurements indicate that it is possible to measure the height of the potential barrier at the junction point by measuring the ohmic nonlinearity with alternating current. This measurement makes it possible to determine the stability of conductivity of the contacts and the superconductor. Deterioration of the properties of these contacts depends on the number of cooling cycles. The nonlinearity is stable below superconducting temperatures. It is noted that this assessment of the properties of contact junctions can reduce the time necessary for life tests and point to an optimum technology for their manufacture.