Hi All...
I want to reduce band gap of Titanium dioxide by doping it with Tungsten trioxide using ball mill. Should i follow this method or some other ?
I think that depends on your goal, the material that you would get out of the ball mill would be a heterogeneous mixture of two powders. This would mean that the band gap measured (I assume you will do this optically), would be a convolution of the two powders not a property of the atomic structure of the material.
If your goal is to make a pellet or powder with a certain bulk bandgap this will be fine. If you are trying to make a material that has a given electronic structure then I don't think this will work.
dear Aarif Shah , I agree with the opinion of Md. Abdur Rahman, you cannot use ball milling for doping because you cannot bind the two materials atomic structure milling is just a physical mixing.
for more information can read;
Optimization Studies of Photocatalytic Tungsten-Doped Titania Coatings Deposited
https://res.mdpi.com/coatings/coatings-03-00194/.../coatings-03-00194.pd
with regards
Milling is simple and not a suitable technique to bring an effective change in the crystal structure as well as in the band gap of desired material. i suggested that you can used electron beam evaporation techniques which is far batter than milling technique, in this process coating is uniform so that electron beam evaporation technique will helps in uniform the crystal structures coating.
Read the answer from Vadim - this is a very tried and true technique. The milling process will alloy the phases to provide intimate mixing. Then, the heat treatments will allow further diffusion to homogenize things. It will likely take 2-3 repetitions for completeness.
The heat treatment can be done in a reducing environment to further change the bandgap. There was a lot written about non-stoichiometric oxides in the past. The reducing environment can be done with h2, CH4, or NH3 - and mixes. You will see a variety of colors: maize, blue, gold.
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