Differential thermal analysis

The differential thermal analysis ( DTA) is a thermal method for material analysis. It belongs to the group of methods of thermal analysis. The DTA uses the fact of a characteristic energy expenditure during the phase transition for the qualitative and quantitative analysis. The measurement is based on a comparison of the temperatures of the sample and a selected reference substance in a symmetrical measuring chamber. In this case, the reference substance to be investigated temperature range no phase transitions. With a constant supply of energy (heat) through the furnace, the temperature is measured in two pots ( the sample and reference ) and recorded the difference over the temperature sensor. Such a temperature difference appears only during phase transitions, and from the curve can thus be draw conclusions on the composition of the sample.

Frequent fields of application of the DTA analysis of mineral substances, such as the dewatering of clays, and clinker phase formation in Zementrohmehlen, the detection of the heat of reaction from the combustion of organic matter, as well as the characterization of plastic materials.

To investigate the polymorphism, which has a special meaning in the pharmacy for characterization of some drugs, the differential thermal analysis is a method frequently used. DME allows to detect this complex phenomenon, and to interpret, especially when the sample to be analyzed is a mixture of several crystalline modifications.

A further developed from the DTA method is differential scanning calorimetry (english differential scanning calorimetry, DSC). While in the DTA, the temperature difference between the two crucibles ( sample and reference ) is recorded as a function of the energy supplied or the temperature of the reference substance directly in the DSC, the heat flow difference is detected therefrom. Thus, characteristic temperatures and caloric characteristics are determined.