Getting a good TiO2 film can be a real challenge. Moisture, temp. etc play a crucial role.
Try this recipe - (u can change the amounts proportionally)
Take 1 gm ethyl cellulose in 20 ml ethanol and dissolve it by slightly warming the solution. You will get a clear solution.
Take 0.5 g TiO2 and add 2.5 ml terpineol. Add 0.5 ml of the above prepared ethyl cellulose solution.
Add excess propanol or ethanol (preferably ethanol) and sonicate for 1hr.
Remove excess ethanol by rotary evaporator or keep the mixture in air for 1-2 days so that ethanol evaporates.
You should get a viscous paste like formulation. In our case one coating gave about 7-8 micron thickness.
You can also use poly-vinyl-pyrolidone (PVP) instead of ethyl cellulose. However, u will have to do optimizations on your own.
Heat the films very slowly in order to avoid thermal shock.
A pre-treatment using TiCl4 and post treatment (after annealing your films) using the TiCl4 would improve adhesion of your films.
You have to repeat screen printing process at least 2 times to get proper thickness. To avoid cracks u should heat your films very slowly. Heat at 50 deg C for at least 10 min. Then increase to 80 deg C for 10 min. You should reach 500 deg C in about 40 min and stay at that temp for 30 min. Then allow the films to cool down to room temp (or at least up to 100 deg C) before taking them off the heater.
Try this recipe - (u can change the amounts proportionally)
Take 1 gm ethyl cellulose in 20 ml ethanol and dissolve it by slightly warming the solution. You will get a clear solution.
Take 0.5 g TiO2 and add 2.5 ml terpineol. Add 0.5 ml of the above prepared ethyl cellulose solution.
Add excess propanol or ethanol (preferably ethanol) and sonicate for 1hr.
Remove excess ethanol by rotary evaporator or keep the mixture in air for 1-2 days so that ethanol evaporates.
You should get a viscous paste like formulation. In our case one coating gave about 7-8 micron thickness.
You can also use poly-vinyl-pyrolidone (PVP) instead of ethyl cellulose. However, u will have to do optimizations on your own.
Heat the films very slowly in order to avoid thermal shock.
A pre-treatment using TiCl4 and post treatment (after annealing your films) using the TiCl4 would improve adhesion of your films.
You have to repeat screen printing process at least 2 times to get proper thickness. To avoid cracks u should heat your films very slowly. Heat at 50 deg C for at least 10 min. Then increase to 80 deg C for 10 min. You should reach 500 deg C in about 40 min and stay at that temp for 30 min. Then allow the films to cool down to room temp (or at least up to 100 deg C) before taking them off the heater.
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