my opinion, TG show the mass loss. we can see mass loss at each temperature very low. For example, the water evaporation is shown at temperature of 125, followed by 431, 664, 794. All of these temperature explain the amorphous state. From 923 to 1000 show the crystallization process and from 1050 to 1500 the crystalline is stable.

Thanks 

Hi, 

Thank you for your answer, however I would like to find an interpretation of these small contributions ! I think it can be related to the fact that amorphous silicon nano particles must be highly oxidized as oxygen diffuse easily into this non crystalline structure (the rate of oxidation must be limited by the crystalline lattice, right ?). At this point, I imagine a thick oxide shell composed of many SiOx (with different x

I think your interpretation is fine, but you must find in the literature, what transformation when they are at temperature 431, 664 and 794. In fact, when above 1050, crystalline formed

The plot depicts a succession of small peaks at 923, 794, 664 ºC; for the dTG/dt signal (mg/min) shown along with the TGA plot of the amorphous nanoparticles. This was not observed for the crystalline silicon nanoparticles. Note that differences between the mentioned temperatures are ΔT = 923-794 = 129 ºC for the first gap, and ΔT' = 794-664 = 130 ºC for the second. By taking the ratio between temperature differences and the selected heating rate (10 ºC/min), we obtain virtually the same time interval, 13 min. It seems fair to say that the observed small peaks have some kind of temporal dependency, seemingly with a periodic character. Notice that the dTG/dt plot tends to amplify the effect of temperature disturbances inherent to the furnace and the temperature control system, usually based at the PID algorithm. You may check the integral constant (with time unit) in use by the PID algorithm, to compare to the above mentioned time interval (780 s). You may check also the derivative constant (also with time unit) to see if it adequately relates with the integral one ― it is often set about 4-fold lower. You may repeat the essay, but setting integral action to zero, thus relying just at PD control; to check if that influences the previously observed (small) peaks. You may be dealing with a non-linear effect, which seemingly occurs only for the amorphous nanoparticles, possibly by their glass transition range. The signalled paper discusses the inherent non-linear character of the glass transition.

Article Aspects of the non-crystalline state

Dear Seh-Yoon Lim,

You'll find the article here : https://www.researchgate.net/publication/306659216_Core-shell_amorphous_silicon-carbon_nanoparticles_for_high_performance_anodes_in_lithium_ion_batteries

Regards,

Julien