Thermal Conductivity of Selenium at Low Temperatures

Abstract

Measurements are reported of the thermal conductivity of glassy selenium and polycrystalline metallic (hexagonal) selenium at temperatures from 2\ifmmode^\circ\else\textdegree\fi{} to above 100\ifmmode^\circ\else\textdegree\fi{}K. At the higher temperatures, the heat conductivity, $\ensuremath{\lambda}$, for the glassy solid is about 1 mw/cm deg. If we write $\ensuremath{\lambda}\ensuremath{\approx}\frac{1}{3}\mathrm{lCv}$, then $l$, the mean free path, is of the order of the interatomic distance. On the other hand, for the high-purity metallic samples, $\ensuremath{\lambda}\ensuremath{\cong}\frac{5}{T}$ w/cm deg. At low temperatures in metallic selenium, $\ensuremath{\lambda}$ varies approximately as ${T}^{2}$, while in the glassy modification $\ensuremath{\lambda}$ behaves in a similar fashion to that expected from earlier observations on soft glass and Pyrex.