I have tried to create TiO2 nanoparticles from sol gel, and when using old sol (milky) for spin coating, it creates a fine powder layer deposited on the substrate. What conditions need to be changed to create a strong thin film on the substrate compared to conventional particle creation. My purpose is to make multilayer TiO2/SiO2 films to learn about photonic crystals. Can anyone with experience in this matter help me? Thank you very much.
i use this volume ratio (TTIP: Ethanol: water: 0.2M HCl = 1: 10: 10: 1)
To create TiO2 nanoparticles, Titanium Tetra-Isopropoxide solution and De-ionized water can also be used in 1:5 Ratio in the presence of 0.1M conc. Sulphuric acid. Particles then formed (in the presence of Ice) can be thoroughly/magnetically stirred with Ethanol (C2H6O) for three hours as a solvent with water in 1:5 ratio. Then sintered at 120-130 degree celsius for 2-3 hours in furnace/oven.
For thin film TiO2 formation , various methods can be used. The quality of thin films can be improved by sputtering in the presence of plasma.
Hi !
Using an aged, milky TiO₂ sol leads to premature hydrolysis and aggregation, resulting in a powdery, non-adherent film during spin coating. You can form a uniform and strong thin film, by using freshly prepared sol with controlled pH (acidic ~pH 2–4), add chelating agents like acetylacetone, and if possible filter before use. Try to optimize spin the coating parameters (e.g., 3000–5000 rpm, 30–60 s), and follow with a soft bake (~100 °C) and high-temperature annealing (~450–500 °C) to densify and crystallize the film.
Hope in these ways you can troubleshoot your problem!
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