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 to similar to 350 K and in magnetic fields from 0 to 10 T is given. A comprehensive mathematical analysis of the semiadiabatic heat pulse technique for heat capacity measurements on solid materials resulted in the development of the necessary formal algorithms for the complete automatization of the data collection process. Simultaneously a procedure for the on-line evaluation of uncertainties in the measured heat capacity data is developed. An approach which eliminates the need for a separate temperature sensor(s) attached to an adiabatic heat shield(s) used to maintain semiadiabatic conditions during heat pulse heat capacity measurements has been proposed and tested. The sensorless technique provides reliable control of the heat transfer inside a vacuum chamber and results in accurate heat capacity data. The calibration results show that the heat capacity can be measured with an average accuracy better than 1% on small samples (similar to 1 g) over the whole temperature region. (C) 1997 American Institute of Physics. [S0034-6748(97)02011-X].