Utilization of DTA and DSC

We wiU now compare these two methods of thermal analysis of solids, a Antilications of DTA 

One of the major uses of DTA has been to follow solid-state reactions as they occur. AU decomposition reactions (loss of hydrates, water of constitution, decomposition of inorganic anions, e.g.- carbonate to carbon dioxide gas, etc.) are endothermic and irreversible. Likewise are the synthesis reactions such as CaO reacting with AI2O3 to form calcium 

DTA is especially suited in the construction of unknown phase diagrams of binary compounds. A hypothetical phase diagram and the DTA curves which would be used to construct it are shown in the following diagram, shown as 3.5.44. on the next page. In this diagram, the endothermic (Endo) peaks point to the right while the exothermic (Exo) peaks point to the left. 

For the most part, the thermal changes observed are specific, but it is wise to cool reversibly, while observing the DTA peaks in cooling so as to be sure exactly what the original peak represents. 

Still another use to which DTA has been employed is the characterization of amorphous materials. The following, given as 3.5.45. on the next page, shows a typical DTA thermogram obtained when a powdered sample of glass is run. 

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