We are studying thermal stability of the SnSb sample through TGDTA analysis. All the measurements were carried out in complete Nitrogen atmosphere (in order to avoid metal oxide formation in air). Alumina crucibles were used during the measurements. In the obtained results, instead of weight loss, unusual weight gain up to 0.9% from the initial weight is seen. Such a result is reproducible for more than 5 times. What would be the reason for this? Before taking the measurements all the calibrations were ensured such as complete N2 atmosphere, crucible without any impurities etc.,
As there is no possibility for oxide formation, I am wondering whether Nitrogen gas form metal nitride compounds under temperature. Do anyone have relevant articles or idea about the problem?
There is no possibility of any chemical reaction with UHP nitrogen gas with metals while performing TGDTA.
I would suggest you should try for XPS. I hope you would get your answer.
Thank you so much Dr. Roy. We are now analyzing the system with oxygen and argon atmosphere to study whether similar changes occur in other atmospheres.
However I hope XPS can help.
As indicated by Dr. Roy also, the purity of purged gas might be the problem, check that too.
Lakshmi... I believe that your alloy is a very low melting one as both metals are low melting ones and the expected eutectic mixture. Depending on the temperature range may you watch your sample in a melting point apparatus. You may then notice whether or not the weight gain occurs after melting. There will be a great tendency of your delicate alloy to get oxidized even with the traces of O2 withing the Nitrogen purging gas. No nitrogen metal reaction under such a dynamic system as with TGA run.... Good luck.
Thank you so much for the response Dr. Barbooti. from the DSC analysis melting point is found to be 425 deg Cel for my sample. But I hope the point you mentioned about melting point analysis will be useful for me. I will proceed with that.
It may be worth to check the following somewhat related discussion, albeit concerned with Cu, rather than with SnSb: https://www.researchgate.net/post/Why_my_TGA_graph_shows_a_weight_gain
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