The transport of heat in isotopic mixtures of solid neon: an experimental study concerning the possibility of second-sound propagation

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Abstract
The thermal transport properties of solid mixtures of the neon isotopes 20Ne and 22Ne have been studied by means of heat-pulse and steady-state thermal conductivity measurements. The results have been interpreted numerically using the Callaway formalism to establish the relaxation rates for phonon scattering. The rate for three-phonon normal processes which is of particular interest can be represented by tau N-1=(4.5+or-0.5)*105x2T4s-1, where x=h(cross) omega /kT and W is the phonon frequency. The phonon scattering by isotopic impurity atoms was found to be 40% stronger than that predicted on the basis of the mass difference alone, but accords well with calculations that include the effects of strain field scattering. The intrinsic process relaxation rates have been used to assess the possibility of second-sound propagation in perfect neon crystals.