we can see that with the change in the amount of the sample the peaks in the DTA diagrams shift and even the intensity and the area under the peak changes, I want to know the reason?
A very nice explanation of the principles of DTA thermal analysis can be found at: T. Daniels, "Thermal Analysis", Kogan Page Ltd., London, 1973, pp. 79-84.
You can find a typical experimental set-up for 'classic' DTA (differential thermal analysis) at Figs. 5.1 and 5.2 (pp. 200 and 201) at my Ph.D. thesis:
Thesis Cristalização de Biomateriais Vitrocerâmicos e Mineralização...
Kiana... salam Alaikum... Typical DTA measurements are performed at small sample size. This is related to the nature of thermal analysis, where in most cases a thermal decomposition occurs. Consequently, the evolution of the gaseous products of the decomposition will have to pass through a thick bed of the sample (in case of larger sample). This will retard the process somehow and longer time will be needed to terminate the decomposition. Thus, the DTA peak will be wider. The point of maximum rate will be shifted to a higher temperature than for the smaller sample. The same explanation is valid for DTA peaks of melting or phase change... Good luck
Carlos Araújo Queiroz Mahmood M. Barbooti dear sir, thank you so much for your help.
If you want to find a principle of DTA measurement, "DTA and Heat-flux DSC measurements of Alloy Melting and Freezing" will be helpful. And you can find in NIST homepage.
Hi '
In my guess the amount of sample would never affects the DTA curve since we used to take almost average quantity to scan. In my point there may be some process error.
please check it.
Hi;
The weight of the sample influences the peak intensity and temperatures. Both these increase with increasing weight. But it is important to say that with smaller amounts of the sample the resolution will be greatly increased.
My regards
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