Thermal conductivity of a rare-earth [formula omitted]-icosahedral compound

Abstract

Thermal conductivity κ of a rare-earth (RE) B 12 -icosahedral cluster compound was investigated up to 900 K. REB 44 Si 2 has Seebeck coefficients exceeding 200 μ V / K at temperatures above 1000 K, while the resistivity rapidly decreases with temperature. ErB 44 Si 2 has the highest power factor. κ of ErB 44 Si 2 was found to take very low values of ∼ 0.015 W / cm / K at 900 K. The RE B 12 -icosahedral cluster compounds in which RE atoms occupy voids among the clusters generally appear to have lower thermal conductivity than boron cluster compounds which do not contain RE atoms. The figure of merit of ErB 44 Si 2 was determined. ZT ∼ 0.04 at 1000 K but the trend is a sharp increase to even higher temperatures.