Dear colleagues,
As you know, The DTA analysis, which is a thermal test, compares the temperature of sample and reference at different times or temperatures to know the changes in sample. In other words, change of temperature between two materials, at a constant and equal heating rate, indicates a chemical or physical reaction in sample.
Now, question is, of course the sample and the reference material are not necessarily the same, so their specific heat capacity is different. So with an equal heat-input rate, their temperature increases at different rates. How does the system compensate this problem in results?
Thanks a lot.
While some of the commercial DTA software could do that automatically, the "raw data" you will get from the DTA will have a slope, then you could fit a baseline to subtract. this should eliminate the difference due to heat capacity of the sample and reference. Generally, the selected reference should be as close to the heat capacity (or thermal mass) of the sample.
The difference in the heat capacity ( sample and reference)determines the position( amplitude) of the scanning baseline . All thermal measurements made during the heating( or cooling) run are made as deviations versus temperature ( or time) from that baseline. C Earnest
I recommend the answers from Kirshon and Earnest , however, to measure the specific heat for a material depending on DTA, the material under investigation and the reference should have the same weight and in this case the difference between their area under the curve will refer to their related differences in their specific heat
In DTA, we have basically two unique crucibles. One of those crucibles is kept empty, which is called the reference, and the sample is embedded in the second one. Reference shows a different heat capacity as a function of time and temperature[Cp (T, t)], likewise, the Cp (T, t) value of the sample is a combination of both sample and its crucible. Therefore, by subtracting the total Cp (T, t) value from the sample from the Cp (T, t) value of the reference, the system can give a pure result for your sample.
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