Thermal conductivity of solid neon

The thermal conductivity of solid neon samples was measured from 0.5 to 10 K. An isotopically purified ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ sample and a ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ sample with 0.15-at.% ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, as well as a sample with the natural isotopic mixture, were studied. Measurements were made at molar volumes between 13.4 and 12.89 ${\mathrm{cm}}^3$/mole. The conductivity is found to increase rapidly with decreasing molar volume. The conductivity is determined primarily by the intrinsic phonon scattering above about 4 K. Normal and Umklapp phonon scattering terms are found to be necessary to make reasonable fits to the data using the Callaway relaxation-rate theory. The functional form of the three-phonon Normal processes can be represented best by ${\tau }_N^{-1\mathrm{}}\propto B_N{x}^2{T}^4$ ${\sec }^{-1\mathrm{}}$, where $x=\frac{\hslash \omega }{\mathrm{kT}}$, $\omega$ is the phonon frequency, and $B_N$ is a constant. These fits show that the enhancement of phonon scattering from isotopic defects due to differences in zero-point energy decreases with molar volume.