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Message Icon Topic: Preparation of transparent TiO2 films. Post Reply Post New Topic
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gabonino
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Quote gabonino Replybullet Posted: 04 March 2004 at 1:14pm

ceec,

I tried Prasas' recipe, and it seems to be quite stable during the very first days: however, after a while, it begins to get too viscous, ending up in the formation of a pale white gel. My solution was almost clear, having the yellow color only after drying it. The time Dr. Prasas tells you about is going to help you with the formation of better chains of TiO2, suitable for your coating....this change, however, will remain unseen under the eyes

Oscar Gabriel Nińo A.
Chemical Engineer
Universidad Nacional de Colombia
M. Sc. Process and Energy Engineering
Technische Universität Berlin
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ceec
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Quote ceec Replybullet Posted: 21 April 2004 at 10:49pm
sorry for bothering again...the coating crystallined at only 100 heating...some crystals stay on the film but not coated...can you tell if  I need to stirr the solution after the addition of HCl...'cos I found there some ppt formed when HCl is added even with very slow speed by a syringe...any ways to solve this?
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Quote DEARWL Replybullet Posted: 11 May 2004 at 8:59am

Dear FORUM

This is my first to there,i have a problem how can i do the TEM of the TiO2 films on the galss?

thanks! 

THANK
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HoKra
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Quote HoKra Replybullet Posted: 12 May 2004 at 7:33am

Hi Forum Members,

I tried to use a binary TiO-SiO sol. I know that a lot of work has been done around this system. However, I faced problems when I tried to mix a sol made of Ti(isoPro)4 with one containing TEOS. Lots of TiO2-precipitates fell out and the sol became a white suspension. Does anyone of you know a recipe for both starting sols which will lead to a transparent binary sol? 

Holger Krause

Student of Microsystemtechnology

IMTEK Freiburg, Germany 

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rammahipal
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Quote rammahipal Replybullet Posted: 28 May 2004 at 12:00pm

Hi

I tried to prepare TiO2 Soln by using Titanium ispropoxide(5ml),Ethanol(35ml) and acetic acid(0.5ml)

but the soln remained white even after 12hrs.

did one some one prepared the soln by this method.

the soln formed is white

Iam not sure whether the soln for med is right or not.

can some one suggest me in this regard

Ram
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HoKra
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Quote HoKra Replybullet Posted: 01 June 2004 at 10:12am

Hi Ram,

try to start with the recipe from M.Prassas (see first Page of the Forum). I used it with several modification concerning the amount of isopropanol.

  I used the following way:

Volumratio Ti(isoPro):isoPro:HCl-2M = 12:60:0,4

Pour the Ti(isoPro) under stirring to the isoPro and ad afterwards the HCl.

The solution becomes transparent after less the 1 hour. However, there may appear some precipitates (not much). Therefor I used a syringe filter (0,2µm pores) to fill the sol in a container for storage. The sol will remain stable if cooled (3°C) for many days (it did not gel after 3 weeks, if cooled).  

I also tried to use it with Ethanol instead of Isopropanol. Right after mixing, the sol was transparent, but after 15 min it became white because of precipitates of TiO altough I used a glovebox with a Nitrogen atmospere. Therefor I think that it is difficult to create a stable Sol using ethanol.

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Holger Krause
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-IMTEK Freiburg, Germany
-University of Applied       Sciences, Muenster, Germany
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rammahipal
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Quote rammahipal Replybullet Posted: 02 June 2004 at 12:50pm

Hi Hogler,

Thanks for your mail.

in the recipe proportionality you mentioned

the ratio of  isoproponal/TiO2 was decreased from the one which M.Prassas Mentioned.

as per what administrator said as u increase the ratio of  proponal to TIO2 precursor the soln remains stable for long time.

any way thanks for your mail.

 i will try with your recipe.

regards

 

Ram
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University of arkansas
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HoKra
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Quote HoKra Replybullet Posted: 03 June 2004 at 5:19am

Hi Ram,

the reason why I am using less Isopropanol is because I would like to decrease the shrinkage. It is correct that a higher ratio of isopropanol/ Ti(isopro) increases the stability of the sol, but on the other hand it also increases the volume-loss of the xerogel. It depends on the thickness you would like to reach and the coating technique you apply which ratio fits best for your application.

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Holger Krause
Student of Microsystemtechnology
-IMTEK Freiburg, Germany
-University of Applied       Sciences, Muenster, Germany
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Nai74
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Quote Nai74 Replybullet Posted: 03 June 2004 at 1:22pm

Hi HoKra,

I'd like to tell you if we increase the Isopropanol/Ti(isopro) ratio we get more sol stability. But the layer will be less thicker!.. is it?

Best regards

Naimi Boubekeur
Ph.D. Thesis
LPMO - CNRS
32, avenue de l'Observatoire
F-25044 Besanēon Cedex France
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rammahipal
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Quote rammahipal Replybullet Posted: 04 June 2004 at 12:43am

Hi Hogler

i tried ur recipe but as soon as i added Ti precursor and HCL the solution become gel with in 5 min.i tried twice.

any further u would like to give.

but thanks for your response.

danken sie.

 

Ram
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University of arkansas
USA
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