HIGH-T(C) SUPERCONDUCTOR POLYMER COMPOSITES - MODELING OF ABNORMAL ELECTRICAL-PROPERTIES AT LOW-TEMPERATURE

High-T(c) 2223-bismuth superconducting pigments have been inserted in a matrix of Fe3+ -doped polyphenylene sulphide (PPS) to obtain new composites with variable properties. The fabrication and the characterization of the various components are briefly described. The electrical resistivity at a low temperature of the composites is reported. In the case of multiphase superconducting pigments presenting various T(c)'s and semiconducting fabrication residues inserted in the polymeric matrix, the composites are characterized by abnormal resistivity evolutions between 20 K and 300 K. A new electrical model is proposed to interpret the behavior of such composites in the full 5 K to 300 K temperature range. Percolation features are taken into account through an empirical description of the electrical complex impedances. The computer calculations allow one to characterize fabrication residues and interfaces between insulating, conducting and superconducting areas in the composites.