The specific heat and thermal conductivity of Eccosorb CR-124 between 800 mK and 6 K

Eccosorb CR-124 is a castable iron-loaded epoxy resin with excellent absorption properties for electromagnetic waves in the GHz range. It is commonly used in low temperature instruments to absorb thermal radiation. The specific heat c(T)c(T) of Eccosorb CR-124 was measured between 800 mK and 6 K with the heat pulse method. The results were fitted to the function c(T)=(0.132±0.003)·T+(0.0053±0.0003)·T3Jkg-1K-1, with T   being the temperature in Kelvin. In addition, the thermal diffusivity D(T)D(T) of Eccosorb CR-124 was determined. At a temperature of 2.3 K, a peak is observed in D(T)D(T). Consequently, the thermal conductivity λ(T)λ(T) of Eccosorb CR-124 features two distinct regimes. Below 2.3 K, it fits the function λ(T<2.3K)=(0.0038±0.0003)·T2±0.1Wm-1K-1. Above 2.3 K, it fits the function λ(T>2.3K)=(0.0057±0.0004)·T1.4±0.04Wm-1K-1.