Spin Coating TiO2: Effects of pH & Alcohol Type

[venus]

Hi everyone!
I'm doing some research on spin coating, my precursor is TiCl4 and I mix it with ethanol, but I have cracks on my films, can anyone help me?
The reaction is:
Ticl4+ ethanol ---> TiO2 + HCl +...
What effects does the pH and the type of alcohol used have? How can I change the viscosity ? Can anyone tell me what happens chemically in this reaction?

 

[Astronuc]

Is it a Ti-based substrate which you are coating? What is the temperature and pressure of the process?

Surface tension (wettability) of the solution could be a factor. Have you looked at what other people have done regarding chemical deposition of TiO₂ films.

The reaction is:
Ticl4+ ethanol ---> TiO2 + HCl +...

What is the water content of the ethanol? One might be getting TiCl₄ + 2 H₂O -> TiO₂ + 4 HCl and perhaps there are some intermediates that interfere with the precipitation process and hence the cracking.

 

[ravenprp]

Hi there! Spin coating is a great technique for producing thin and uniform films, but it can also be quite tricky to get the desired results. In your case, the cracks in your TiO2 film could be due to a variety of factors, including the pH and type of alcohol used.

Firstly, the pH of your solution can greatly affect the final film quality. A high pH can lead to the formation of larger particles, which can result in an uneven film and potentially cause cracking. On the other hand, a low pH can cause the solution to become too acidic, which can also affect the film formation process.

Additionally, the type of alcohol used can also play a role in the formation of your film. Different alcohols have different viscosities, and this can affect the thickness and uniformity of your film. Ethanol, for example, has a lower viscosity compared to other alcohols like isopropyl alcohol. You may want to experiment with different types of alcohols to find the one that works best for your particular precursor and process.

In terms of changing the viscosity, you can try adjusting the concentration of your precursor or the alcohol in your solution. This can help to fine-tune the viscosity and potentially improve the film quality.

As for the chemical reaction that is occurring, the mixing of TiCl4 and ethanol results in the formation of TiO2 and HCl as byproducts. This is a hydrolysis reaction, where the TiCl4 reacts with water (present in the ethanol) to form TiO2 and HCl. The exact mechanism of this reaction can vary depending on factors such as temperature and pH.

I hope this helps to answer your questions and provides some insights into the potential causes of the cracks in your TiO2 film. Good luck with your research!