COMPARATIVE-STUDY OF ELECTRONIC TRANSPORT-PROPERTIES IN BULK AND PULVERULENT SAMPLES

The problems related to electric measurements performed on powder are presented, In order to compare the results with those obtained on the bulk two amorphous compounds are selected : a ''low temperature carbon'' (HTT 600) and a molybdenum sulphide MoS2,8. D.c. and a.c. electric transport properties are analyzed in terms of hopping conductivity between localized sites. The electronic transport due to the hops is explained by means of tunnelling effect (QMT model). The interpretation of the experimental results is obtained by the use of numerical approach. The parameters characterizing the properties of the compounds under study, bulk or powder, are comparable. However in the case of the pulverulent samples, the analysis of the results appears more difficult. The comparative results are coherent if the measurements performed on powder are chosen in the high frequency domain and at low temperature.