Working principle & Instrumentation
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| DTA instrumentation |
Thermal analysis are Techniques in which a physical property of a substance is measured as a function of temperature whilst the substance is subjected to a controlled temperature programme certain techniques lie in this here we discuse DTA in deatail.
DTA mesures the temperature difference between the sample and refrence materila as they both undergo the same temperature programme. The record is the differential thermal or DTA curve or thermogram; the temperature difference (∆T) should be plotted on the ordinate with endothermic reactions downwards and temperature or time on the abscissa increasing from left to right. The term quantitative differential thermal analysis (quantitative DTA) covers those uses of DTA where the equipment is designed to produce quantitative results in terms of energy and/or any other physical parameter.
Sample Preparation Samples are usually finely ground and placed in a sample holder. It's crucial to have a representative sample and to account for factors like sample size and packing density, as they influence the thermal behavior.
Results interpretation The base line corresponds to the portion or portions of the DTA curve, thermogram or thermograph for which ∆T is approximately zero.
A peak is that portion of the DTA curve which departs from and subsequently returns to the base line.
Endothermic peaks or endotherm, is a peak where the temperature of the sample falls below that of the reference material, i.e., ∆T is negative.
Exothermic peaks or exotherm, is a peak where the temperature of the sample rises above that of the reference material, i.e., ∆T is positive.
Peak width is the time or temperature interval between the points of departure from and return to the base line. There are several ways of interpolating the base
line as peak height peak width , peak area etc.
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| DTA thermogram |
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