PREPARATION AND THERMOELECTRIC PROPERTIES OF SOME ARSENOPYRITE PHASESBASED ON RUSB2-2XTE2X AND RUSB2-2XSE2X SOLID-SOLUTIONS

The synthesis and some properties of several arsenopyrite phases based on RuSb2-2xTe2x and RuSb2. Se-2x(2x) solid solutions is reported. The existence of solid solutions with the arsenopyrite structure in the R uSb22 degrees (x over tilde)Te-2x system for 0.25 < x < 0.65 was confi rmed. In the RuSb2-2xSe2x system, no series of solid solutions was fou nd, and only the RuSbSe phase was prepared in single phase form. In an effort to assess the potential of these materials for thermoelectric applications; electrical resistivity, Seebeck coefficient, and thermal conductivity were measured between 300 and 1000 K. Low thermal conduc tivity values were achieved for the ternary and quaternary composition s investigated, about five times lower than those obtained for binary compounds such as IrSb2 and CoSb2 at room temperature. In these materi als, scattering of the phonons by electrons transferred between mixed valence ions accounts for the low thermal conductivity observed. Despi te these low values, the samples are characterized by low carrier mobi lity and high electrical resistivity values, resulting in thermoelectr ic figures of merit lower than state-of-the-art thermoelectric materia ls. (C) 1997 Elsevier Science Ltd. All rights reserved.