A 3-350 K FAST AUTOMATIC SMALL SAMPLE CALORIMETER

A description of a fully automated calorimeter for rapid measuring the heat capacity of solids in the temperature region from similar to 3 t o similar to 350 K and in magnetic fields from 0 to 10 T is given. A c omprehensive mathematical analysis of the semiadiabatic heat pulse tec hnique for heat capacity measurements on solid materials resulted in t he development of the necessary formal algorithms for the complete aut omatization of the data collection process. Simultaneously a procedure for the on-line evaluation of uncertainties in the measured heat capa city data is developed. An approach which eliminates the need for a se parate temperature sensor(s) attached to an adiabatic heat shield(s) u sed to maintain semiadiabatic conditions during heat pulse heat capaci ty measurements has been proposed and tested. The sensorless technique provides reliable control of the heat transfer inside a vacuum chambe r and results in accurate heat capacity data. The calibration results show that the heat capacity can be measured with an average accuracy b etter than 1% on small samples (similar to 1 g) over the whole tempera ture region. (C) 1997 American Institute of Physics. [S0034-6748(97)02 011-X].