Hi

Firstly, glass substrate for coating should be cleaned with acetone in ultrasonic bath,

followed by ethanol and lastly with di-ionized (DI) water for 10 minutes. The last step is blowing the glass substrate with N2 gas for drying purpose.

Then, the synthesized TiO2 NPs can be suspended in ethanol and sonicated for 10-15 minutes. Then TiO2 solution can be deposited on the glass substrate using spin coating technique with 6000 rpm

for 1 minute. The deposition can be done for 5 times or more depending on the thickness required. The deposited thin film can then be dried at 150º C for 10 minutes to vaporize the solvent. Lastly, then annealing is done at 450º C for 1 hour to restructure the crystallinity of the thin film.

TO prepare different thickness of you material by spin coating follow  the next steps.

1- Clean your substrate well and fix it on the spin coater.

2- put on or two drops on the substrate according to area of the substrate.

3- start the spin coater at certain ppm.( fix it all the time of the experiment).

4- Make annealing for 1 h at 100 deg to reduce any pores  through the film.

5- If you want to in crease the thickness of the material repeat the aforementioned steps.

I wish this is useful and help you.

Thank you Anupma Thakur and Majibul Babu for your valuable input. I shall implement the method recommended by Anupma Thakur and see if I acquire the expected results.

From powder, this is not possible. There is no such thing as a 'nanopowder' where there are free, independent particles < 100 nm. The word is an oxymoron. You have a collection of fused post- and sub-micron aggregates and agglomerates.

Dear Prof. Alan,

Greetings!

In continuation to your observation, i would like to seek a quick clarification. If we have synthesized TiO2 nano particles (NPs) in the presence of suitable capping agents in a manner that we have NPs in the range of 10 to 15 nm or if we were to purchase a commercially available TiO2 NPs which are dispersible in any solvent say water due to the presence of suitable capping agents, the existence of independent Nano particles even below 100 nm should exist.

If i were to understand the point your are driving home, we are suppose to sonicate and spin coat the dispersion?

If we were to make a thin film of TiO2 NPs using either dip coating or spin coating methods, are there ways to get an absolutely agglomerate free thin film?

Thank you for valuable time in advance sir.

Warm regards

Ganesh

Can refer to this work for more clarity,

This may help to resolve your query. They have given a detailed procedure starting from TiO2 precursor and not tiO2 powder.

"Nanostructure Thin Films of Titanium Dioxide Coated on Glass and Its Anti UV Effect for Living Organisms "

DOI- 10.2174/157341310791171180

Thank you Sai Prasad. Agglomeration issue still needs to be addressed though...

Regards

Ganesh

Ganesh K M

I reiterate - if your TiO2 is in powdered form then there's no way you can get a thin film by spinning the material onto a substrate even after so-called 'dispersion'. This is because there are no free, independent, discrete particles < 100 nm in a powder. The normal routes to a thin film are sol-gel (e.g. titanium isopropoxide in alcoholic solutions) or evaporative processes. In a nanodispersion (particles < 100 nm) then the separate particles can be stabilized and kept discrete by steric or charge ('electrostatic') routes. Note that suspensions of TiO2 < 100 nm are typically made for the wood varnish industry - these are completely transparent as your 10 -15 nm TiO2 sol would be too. As Rudy Rucker said: I think dry nanotechnology is probably a dead-end' (August 2002). Take a look at these webinars (registration required) for more information on the fundamentals:

Dispersion and nanotechnology

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat

Adhesion and cohesion

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W180725AdhesionCohesion