Electrical resistivity measurements in superconducting ceramics

Electrical resistivity measurements have been done in (Y, Ba, Cu, O) - and (Y, A1, Ba, Cu, O) - based superconducting ceramics. The sintered specimens were prepared by applying gold electrodes and winding on the non-metalized part with a copper strip to be immersed in liquid nitrogen for cooling. The resistivity measurements have been done by the four-probe method. A copper-constantan or chromel-alumel thermocouple inserted between the specimen and the copper cold finger has been used for the determination of the critical temperature Tc. Details of the experimental set-up and resistivity versus temperature plots in the LNT-RT range for the superconducting ceramics are the major contributions of this communication. (author)