THERMOELECTRIC PROPERTIES OF THE SEMICONDUCTING CHEVREL-PHASE MO2RE4SE8

We have prepared and measured the electrical resistivity, Seebeck coef ficient, and thermal conductivity of the Chevrel material Mo2Re4Se8 in the 300-1000 K temperature range. The results show that Mo:Re,Ses is a semiconductor with a relatively low thermal conductivity. The semico nducting nature of this compound is consistent with theoretical predic tions based on the number of valence electrons per [Mo-6] cluster. The crystal structure of Chevrel phases contains several voids of differe nt sizes and shapes which can be filled by a variety of atomic element s. The filling of these interstices may be used as a means to achieve low thermal conductivity values by increasing the phonon scattering. T his represents an attractive possibility considering that low thermal conductivity is one of the requirements for a good thermoelectric mate rial. Various approaches to determine the potential of Chevrel phases for thermoelectric applications are presented and discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.