Abstract
A new isoperibol type calorimeter for laser-flash heat capacity measurement over the temperature range from 80 to 300K is described. In the new calorimeter the sample is surrounded by a heat sink made of copper, of which temperature is kept nearly the same as that of the sample; thus the heat loss from the sample is considerably diminished. The temperature of the heat sink is detected by a Minco platinum resistance thermometer, and the temperature difference between the heat sink and the sample is sensed by a copperconstantan thermocouple. In this way, the temperature of the sample can be determined with an inaccuracy of ±0.01K, which is much better than that of ±0.2K for the conventional laser-flash calorimeter using thermocouple as the temperature sensor. In order to test the reliability of the calorimeter, the heat capacity of the α-alumina single crystal was measured from 80 to 300K. The results were compared with the N. B. S. data, and the standard deviation was ±0.28%. The imprecision and the inaccuracy of the heat-capacity measurement using this calorimeter are estimated to be within ±0.3% and ±0.5%, respectively.
