Examples of DTA and DSC under Extreme Conditions

For this summary, forms of thermal analyses under extreme conditions are described for the measurement of heat and temperature, as dealt within Sects. 4.1-4. The distinction between DTA and DSC seen in these methods is described in Appendix 9. In Appendix 10, DTA or DSC at very low and high temperatures and DTA at very high pressures are mentioned. This is followed by a discussion of high-speed thermal analysis which, in some cases, may simply be thermometry. Finally, micro-calorimetry is treated. One might expect that these techniques will develop in this century [1]. The numbers in brackets link to references at the end of this appendix. 

Low-temperature DTA and DSC needs special instrumentation [2]. In Fig. A. 10.1 a list of coolants is given which may be used to start a measurement at a low temperature. Fromabout 100 K, standard equipment can be used with liquidnitrogen as coolant. The next step down in temperature requires liquid helium as coolant. A differential, isoperibol, scanning calorimeter has been described for measurements on samples of 10 mg in the 3 to 300 K temperature range [3]. To reach even lower temperatures, especially below 1 K, one needs again another technique [4], but it is 

By surrounding the DSC with low-temperature baths lower temperatures can be reached as indicated. For other calorimeters see Sect. 4.2. 

As an added feature of larger cooling capacity, faster cooling rates are possible. The computations below apply to a disk-like sample  

High temperature and pressure DSC and DTA needs special materials for the construction of the calorimeter, as is shown in Figs. A.10.2 and A.10.3. At high temperature, the control of heat loss and gain by radiation becomes important, at high pressure the strength and high mass of the enclosure must be considered. 

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