Experimental determination of phonon thermal conductivity and Lorenz ratio of single-crystal bismuth telluride

We use a magnetothermal resistance method to measure the lattice thermal conductivity of single-crystal Bi 2 Te 3 from 5 to 60 K. Lattice thermal conductivity is calculated by extrapolating the thermal conductivity versus electrical conductivity curve to a zero electrical conductivity value. Our results show that the measured phonon thermal conductivity follows the e ΄ min/T temperature dependence and the Lorenz ratio corresponds to the modified Sommerfeld value in the intermediate temperature range. Our low-temperature experimental data and analysis on Bi 2 Te 3 are a complement to previous measurements of Goldsmid (Ref. 17) and theoretical calculations by Hellman et al. (Ref. 18) at higher temperature 100-300 K.