Thermal conductivity of YbB44Si2.

The low temperature thermal conductivity of YbB₄₄Si₂ is investigated. The rare earth boron icosahedra compounds are of interest as potential high temperature thermoelectric materials. The thermal conductivity of YbB₄₄Si₂ is relatively large below room temperature, showing crystalline behavior and having a peak exceeding 10 W/m/K at ∼35 K. This departs markedly from the low amorphouslike behavior observed in another rare-earth-containing boron cluster compound: RB₆₆ (R=rare earth). From a comparison and consideration of the various models, we conclude that disorder is the important factor in the generally observed low thermal conductivities of these compounds, with RB₆₆ being exceptionally disordered as compared to YbB₄₄Si₂. [ABSTRACT FROM AUTHOR]