Isochoric thermal conductivity of solid nitrogen

The isochoric thermal conductivity of solid nitrogen is investigated on four samples of different densities in the temperature interval from 20 K to the onset of melting. In α-N2 the isochoric thermal conductivity exhibits a dependence weaker than Λ∝1/T; in β-N2 it increases slightly with temperature. The experimental results are discussed within a model in which the heat is transported by low-frequency phonons or by “diffusive” modes above the mobility edge. The growth of the thermal conductivity in β-N2 is attributed to the decreasing “rotational” component of the total thermal resistance, which occurs as the rotational correlations between the neighboring molecules become weaker.