With all due respect, this thermograph is a mess. Endotherms use to be melting or boiling, exotherms can be cristallization. Reaction(s) can be considered in both cases. Phase changes are more difficult to establish. You can look for other similar or equal thermal analysis, given the material you have and compare results. Good Luck!

Victor, thank you! I'll try to use thermal X-Ray and compare the results.

I quickly looked at your DSC data. Unless you don't have any additional information, DSC will not tell you which phase transformation occurs, it will only give you information about the overall energy dissipation. Unless you don’t have a known material, DSC curves should always be verified by other methods.

You could try an in-situ phase analyses by X-ray diffraction, but please keep in mind that by using conventional X-rays the exposure times are very long, so in contrast to your DSC analyses (constant heating rate of some K/min), you will have to keep the material on the chosen temperature for long time to get sufficient peak-to-background-ratio. This might affect your results regarding the phases. I don’t know your material, but might short heat treatments followed by water quenching feasible to “freeze” your structure and afterwards do post-mortem microstructure and phase analyses? Otherwise, the use of hard X-rays (synchrotron radiation) would be advisable, as the exposure time is seconds instead of hours. In case, unknown, non-equilibrium … phases occur, interpretation of the diffraction pattern might be difficult as well if there are no related entries in a database.

Carsten, thank you a lot for your answer! I'll take into consideration features of the in-situ X-ray analysis if I use it. But may be you know any program, which can analize peak profile, define baseline and so on?

I typically use fit2D (for peak integration) and CMPR software together with PDF2 database (for peak analyses). The database you have to purchase, fit2D and CMPR are free of charge.

Dear Vadim,

not sure whether this helps, but since you ask for software solutions, Netzsch used to offer a program called Thermokinetics offering some possibilities in kinetic analysis including multivariate nonlinear regression capabilities used in first selecting from different pre-defined reaction models (naturally also with the option to combine several of these in different ways), then using this background information to produce a fit to several measurements typically performed at different heating rates.

I hope I have described this correctly. I would not know, though, whether these options are state of the art in other programs, too, nowadays - and in any case, as far as I know Thermokinetics is a commercial package which comes with a quite substantial price tag attached to it.

Best regards,

Dirk Lehmhus

you can use the combination of modulate DSC and X-ray difraction

Hi Vadim, I believe is possible to obtain some information of the DSC obtained but, just is necessary to be sure about experimental details, I means, details about the setup of DSC.

Carsten, thank you for advices, I'll try to use this program, and I already have experiences in using PDF2 base.

Dear Dirk, I've never heard about Thermokinetics, but I think it may help me with my DSC analyzes. Many thanks!

Marina, I wish to use, but I have no possibility for it)

E. Garcia-Sanchez, what experimental details do you mean?

Hi Vadim

Very useful comments before. I should like to add some experimental tips that could help:

1-Have you correctly substracted the baseline?

2-Run your DSC with the minimum mass possible (this could help to separate peaks in case reaction or transformation enthalpies are large)

3-Run your DSC with the maximum mass possible (this could help to detect peaks in case reaction or transformation enthalpies are small)

4-Run DSC of individual chemicals, for exmple a DSC of only GLYCINE and a DSC of only NITRATES and try to indentify some features of these patterns in in total DSC.

5- If your DSC suggests a temperature where some process finished, stop your reaction there and make XRD of the products at that point.

Good luck!

Dear Vadim

Try to run a simultaneous DSC-TG (Dif.. Scan..Calor..- Thermogravimetry) since the mass change can give you valuable information, correlated to DSC.

Miguel

how do you get the baseline, type of crucibles used in the test, atmosphere, some times with low energy transformations are critical all these details. but I believe one f the most important is the procedure for obtain the baseline

Hi, Vadim,

Indeed if the experimental procedure was correct and you really have the superposition of endo- and exo-stages the only possibility to get info about each stage is to create the appropriate multi-stage kinetic model . NETZSCH software can help but you have a lucky chance to try the CISP ForK kinetics software which is designed for these very complex cases. You can try it for free, moreover if you contact me we can try to analyse your data together as CISP is in SPb and I am the head of this project.

1% : your DSC machine is damaged

98.999% : you don't follow the DSC manual

0.001%: the curve is right.......

Hi, Everyone! Sorry for my delayed response. Now is time to finish this work and I'm trying again to find out what hapenned in my system.

Dear Migel, I followed your second advice and results are attached to the post.

As it seems the main problem is in the correct definition of the baseline.

E. Garcia-Sanchez, I think that you're quite right. But, unfortunately, I have to analyze only data I have from this experiment and I can't change its conditions.

Dear Arcady, I'm very intrested in your software and I've already downloaded it. But how this software package can help me in baseline obtaining?