Specific heat measurement at low temperature by thermal radiation calorimetry

Heat capacity of a disk-shaped specimen was measured in the temperature range from 150 to 310 K by means of a technique of thermal radiation calorimetry. The specimen is heated and cooled by a cylindrical heater in a vacuum chamber kept at liquid nitrogen temperature. Surfaces of the heater and the specimen were blackened with powder chemicals mixed with Bi₂O₃ and MgO to achieve the high and constant hemispherical surface emissivity. The temperature dependence of the emissivity was derived from the spectral emissivity in the wavelength range from 3 to 200 μm. Results of the measurements on Ni and fused quartz specimens were discussed