Anisotropic transport in single-crystal molybdenum bronze, Li$_{0.33}$MoO$_{3}$

We present transport measurements (resistivity, thermopower, thermal conductivity) on single crystals of the quasi-one-dimensional semiconductor Li$_{0.33}$MoO$_{3}$ in the temperature range 200-500 K. First synthesized and studied long ago,\footnote{B. T. Collins {\it et al.}, J. Sol. St. Chem. {\ bf 76}, 319 (1988).} the thermal and thermoelectric properties for this compound have not been previously reported. We find extreme anisotropy in the Seebeck coefficient within the $a-c$ planes, with $S_c-S_a\simeq 300 \mu$V/K near room temperature. The thermal conductivity at room temperature in the $a-c$ planes was $\sim 1.5-2$~W/mK and 7-8 times smaller along $b^*$. We also report x-ray studies of the out-of-plane ($b^*$) lattice constants indicating a small structural transition at $T\approx 350$~K that coincides with anomalies in the transport properties.