I have synthesized carbon coated material. however when I performed TGA, there is weight gain in my bare sample and weight loss in carbon coated sample?
It would be better if you can reveal your composition and percent of weight gain. And you can easily check XRD to study what was happening at that stage.
Hi, increased weight means that your sample absorbs or reacts with the purging gas. The most common purging media are nitrogen and air. Nitrogen is inert (i.e., does not react) for most common materials at usual conditions, so it is the absorption then. Air can also oxidize materials due to the oxygen. Since your carbon-coated samples do not lose weight, I guess it is the absorption case and the coating blocks it.