Electrical properties and longitudinal modulus of superconductor/polymer NdBa2Cu3O7-delta/PVC composites

High temperature superconductor NdBa2Cu3O7-delta/poly(vinyl chloride) (Nd12 3/PVC) composites have been prepared by cold press and hot press methods. A ddition of PVC resulted in increase of the electrical resistivity with perc olation occurring between 0.3 and 0.5 Nd123 volume fraction for both prepar ation methods. Although the samples showed some form of magnetic levitation at liquid nitrogen temperature, they do not show any zero-resistance tempe rature indicating the lack of effective superconducting percolative path. T he density deviates from the linear calculated value with increasing Nd123 content at 0.3 volume fraction for the cold press and at 0.6 for the hot pr essed samples due to increasing porosity. X-ray powder diffraction patterns suggest that the Nd123 crystals tend to align when the composites are prep ared by hot press method. A resistance anomaly is observed at 90 K in the h ot press composites indicating improved electrical contact between the alig ned Nd123 grains. The longitudinal modulus increases as Nd123 content is in creased. (C) 2001 Kluwer Academic Publishers.