Thermal conductivity of solid hydrogen at low orthohydrogen concentrations

Lattice thermal resistance mechanisms are considered in solid parahydrogen containing o−H2 impurity molecules, in the temperature range (T < 4°K) below the heat conductivity maximum. It is shown that for o−H2 concentrations c < 1%, inelastic phonon scattering on isolated o−H2 molecules is significant, producing a contribution to thermal conductivity of K ∼ T/c. At c > 1% changes in thermal flux within the crystal are connected mainly with absorption or emission of phonons by the system formed of pairs of o−H2 (K∼ T3/c2). The results obtained are compared with experiment.

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