This is very interesting discussion. Because based on temperature one nano-material can be converted into another one. For example, If we heat MnO2 nano-particles at about 1000 degree C, it can be converted into Mn3O4 nano-particles.

The increase in nanoparticle size occurs by either Ostwald ripening (for more soluble materials) or by oriented attachment (for less soluble crystals). Both processes depend on the temperature (at least through the diffusion via kT). Thereby, higher temperature causes coagulation of grain boundaries which leads to formation of clumps which is due to enhanced Ostwald ripening process at higher temperature.

• Actually my phd about nano thermoresponsive polymer and its applications as drug delivery. If you have any question about this subject I will be happy to answer it.

Yes, mostly nanomaterials behave differently at different temperatures. Because changes occurred on their microstructure and atomic configuration can well study when they are subjected to thermal analysis. Many researchers observed new phases and additional exothermic and endothermic peaks in nanostructured materials, which were not present in their bulk counterparts. The new peaks and phases are explained on the basis of grain growth process and their microstructure and atomic configuration changes when exposed to high temperature. A large fraction of atoms in nanoparticles are surface atoms and these atoms have significant influence on the thermal properties of nanostructure materials. Structural changes can be expected in small particles because of the large amount of free energy associated with their grain boundaries. The energy associated with the interface regions becomes substantial when the size of the crystallites is in nanosized regime and it may influence phase transitions in nanophase materials.

Similarly the nanomaterials significant behaviour at elevate temperatures can be easily be observed in chemiresitive based sensing application.

As temperature increases crystallite size increases and also phase may be change. In the same phase for different crystallite size behavior will be different.

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