Transport studies of bulk ${\mathrm{Pb}}_{0.2}$${\mathrm{Hg}}_{0.8}$${\mathrm{Ba}}_2$${\mathrm{Ca}}_{1.75}$${\mathrm{Cu}}_3$${\mathrm{O}}_{\mathit{x}}$

Measurements of the resistance versus temperature R(T) were made on samples of ${\mathrm{Pb}}_{0.2}$${\mathrm{Hg}}_{0.8}$${\mathrm{Ba}}_2$${\mathrm{Ca}}_{1.75}$${\mathrm{Cu}}_3$${\mathrm{O}}_{\mathit{x}}$ above their superconductive transition temperatures. Current-voltage (I-V) characteristics were also studied at 77, 27, and 4.2 K in applied magnetic fields varying from 0 to 4.5 T. The R(T) data confirmed the visual observation that the samples were granular. The I-V curves were generally fit best by a modified Ambegaokar-Halperin model from which were obtained the resistance of the samples, the critical current density, and the pinning potential. The first two properties were dominated by the granular nature of the samples, whereas the pinning potential represented an intrinsic property of the material.