Thermoelectric power of quasi-one-dimensional Nb 3X4 with X= S, Se and Te

Abstract

The thermoelectric power of linear chain synthetic metals Nb 3 X 4 (with X= S, Se and Te) was measured from 5 to 300 K. The thermopower is negative indicating a dominant transport by electrons. Common to three compounds, in lower temperature regions the thermopower rises linearly with temperature but soon saturates. With respect to Nb 3S 4 and Nb 3Se 4 we have found no special anomaly of the thermopower except for a little higher magnitude. With respect to Nb 3Te 4 anomalies in the thermopower vs temperature appear at about 80 and 20 K which are explained in terms of the charge- density-wave phase transition from the simultaneous measurement of the resistivity and the observation of the electron diffraction patterns.