Physical properties of skutteruditesYbxM4Sb12, M = Fe, Co, Rh, Ir
Institut für Experimentalphysik, Technische Universität Wien, 1040 Wien, Austria
2 Institut für Physikalische Chemie, Universität Wien, Währingerstraße 42, 1090 Wien, Austria
3 Laboratoire de Chimie du Solide et Inorganique MoléculaireUMR CNRS 1495, Université de Rennes 1, avenue du Général Leclerc, 35042 Rennes, France
Published online: 15 April 2000
A series of compounds , , were synthesised by reaction sintering. From Rietveld refinements isotypism was determined in all cases with the -(skutterudite)-type, space group -No. 204. These refinements also served to derive the Yb-content in the samples. There is a systematic trend for the Yb-occupancy in the parent lattice , revealing a gradual decrease of the Yb-content from x=0.8 (), x=0.5 (FeCo), x=0.2 (Co), x=0.1 (Rh) to (Ir). This dependency seems to correlate with the thermal stability of the ternary compounds: a true ternary compound forms for , whilst for stable binary skutterudite compounds already exist. Measurements of various bulk properties revealed the absence of any long range magnetic order in this series of compounds. While the samples rich in Yb behave metallic like, the Rh and Ir based skutterudites show a semiconducting-like resistivity which at lower temperatures is characterised by variable range hopping in the presence of strong Coulomb interaction. Although exhibits a Seebeck coefficient up to about 150 μV/K, figures of merit ZT generally are below 0.1 near room temperature, primarily due to the large resistivities of the sintered material.
PACS: 72.15.Eb – Electrical and thermal conduction in crystalline metals and alloys / 72.15.Jf – Thermoelectric and thermomagnetic effects / 84.60.Bk – Performance characteristics of energy conversion systems; figure of merit
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000