AN ADIABATIC LOW-TEMPERATURE CALORIMETER FOR HEAT-CAPACITY MEASUREMENT OF SMALL SAMPLES

A small sample adiabatic calorimeter for measuring heat capacities in the temperature range 60-350 K using the Nernst method has been constr ucted. The sample cell of the calorimeter is 6 cm(3) in the internal v olume, equipped with a miniature platinum thermometer and surrounded b y two adiabatic shields. Two sets of 6-junction chromel-copel thermoco uples were mounted between the cell and the shields to indicate the te mperature differences between them. The adiabatic conditions of the ce ll were automatically controlled by two sets of temperature controller . A mechanical pump was used to pump out the vapour of liquid nitrogen in the cryostat to solidify N-2 (1), and 60 K or even lower temperatu re was obtained. The performance of this apparatus was evaluated by he at capacity measurements on a-alumina. The deviations of experimental results from a smoothed curve lie within +/-0.2%, while the inaccuracy is within +/-0.5% compared with the recommended reference data in the wole temperature range.