The thermal diffusivity of molecular cryocrystals
V.V. Sumarokov1, A. Jeżowski2, P. Stachowiak2, and Yu.A. Freiman1
1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Nauky Ave., Kharkov 61103, Ukraine
2W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław, Poland
Received November 12, 2018
Low-temperature thermal diffusivity of molecular cryocrystals (O2, N2, CO, N2O and CO2) has been investigated and some anomalies were found. The thermal diffusivity of these crystals vary by more than 4–6 orders of the magnitude in the temperature range from 1 K up to their triple points. The thermal diffusivity displays jumps at the phase transition points. It has been found that the thermal diffusivity of solid oxygen is nonmonotonic. Below 4 K, the temperature dependence shows a plateau which is due to the fact that both the heat capacity and the thermal conductivity have the cubic temperature dependence in this temperature range. For the cryocrystals of the nitrogen group, a similar plateau is shifted to lower temperatures. The temperature dependence of the equali-zation time for these crystals is studied.
Key words: thermal diffusivity, thermal conductivity, specific heat, density, molecular cryocrystals.