Thank you dr for your replay

,but does it consume the loss in yield,and does the effect of temperature decrease or increase size ?

And could we start with aluminium hydroxide as precursor to get aluminium oxide

The other way to controlling the size of particle in nano scale is to using surfactants like PVA (polyvinyl alcohol) ,PVP (Polyvinyl pyrrolidone) ,etc because this component can prevent the agglomeration of the early formed particles .

And about the producing nano particle the alternative method is to increasing the deposition rate because with this method the size and size distribution of particle can be enhanced and if the surfactant component be at the media, they can prevent the secondary growth and then you can reach particles with narrow size distribution.

Thank u dr for replay

but i wander could annealing change the phase,size only or could change the shape؟

fine Dr ,but the paper study the effect of temperature on size

while the structure still tetragonal ,so temperature doesn`t affect on shape?

About the shape of particles we cant say absolutely that increasing the annealing temperature can change the shape of particle but we can understand that temperature can increase the growth rate of some direction and this can be affect even the shape of particles but this is about the SnO2 particles not alumina but we can generalize the result of this paper on your work that temperature may be affect on the size and shape of crystalline particle by changing the rate growth of some direction because crystalline materials have anisotropic properties .

Hi Alaa

Alumina can be used as an active catalyst as it showed acidic sites (mainly Lewis acidic sites) and also it can be used as a support and this is due to its high surface area, mechanically stable  and the porous structure.

Please find the attached paper that discussed the different phases of alumina and the effect of the precursor, calcination temperature on the prepared alumina catalyst 

Have a good day

Ahmed