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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: 09 June 2004 at 8:55pm

Rammahipal,

you can try an EDX analysis......I do not know so well about the technique, but from what I have seen, you can make it at the same time you do a SEM. I hope this helps, and I hope someone elese gives further information about this, if I am right

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Oscar Gabriel Niño 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: 09 June 2004 at 11:37pm
Quote: Originally posted by rammahipal on 04 June 2004

Hi Holger

i did the experiment in a hood not in a nitrogen atmosphere that might  be the reason for not working.

once again thanks lot for ur reply

i will try to work it in nitrogen environemnt glove box

regards

 


Hi Holger,

Is that critical the preparation of sol should be in nitrogen atmosphere? We are lacking of such facility. Also, if I increase the TIP concentration, I can observe some big crystal on the substrate after drying at 100C. Any suggestion on it? Thx!

 

 

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rammahipal
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Quote rammahipal Replybullet Posted: 10 June 2004 at 12:57am

Hi

I used spectra photometer for abcsorbing UV Visible spectroscopy of the TiO2 Film formed.

Did some one worked on it.

as i wasn't able to get any greeat absorbance in the wave format and also the absorbance was too low.

 is it due very thin film properties or any other reason

can some help me in this regard.

Ram
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University of arkansas
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HoKra
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Quote HoKra Replybullet Posted: 14 June 2004 at 3:42am

Hi Ceec,

the Ti(isopro) reacts pretty easy with the atmospheric water. I am not sure about the exact reaction, but you can see fog evaporating while preparing the sol. Also you have precipitates of TiO2 which will affect the sol stability.

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Holger Krause
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Laser-one
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Quote Laser-one Replybullet Posted: 09 July 2004 at 8:25am
One way to improve sol stability is to add Acetylacetone to the freshly prepared sol (by Prassas formula). Anyone tried it?
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Quote HoKra Replybullet Posted: 19 July 2004 at 6:34am

I have two questions.

First: Why is it necessary to wait 24h before making a TiO2 coating, as M.Prassas proposed? I had good results by coating after one hour

Second: Why is a temperature treatment necessary? Is it to remove the solvent or are there other reasons?

I guess there must be some obvious answers, so I hope some one can tell me the reasons.

Thanks in advance.

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gabonino
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Quote gabonino Replybullet Posted: 19 July 2004 at 3:38pm

Holger,

regarding your questions:

First: Probably the purpose of the aging of the sol is to achieve more viscous sols, that will lead into thicker layers of the coating. I am not sure on such affirmation, but probably someone more involved with the process can contradict this theory.

Second: Thermal treatment is made on coatings in order to achieve several purposes; on those, I can mention densification, which will lead to a more densified coating, less porous and probably more resistant in mechanical matters. On the other side, thermal treatment can be used in order to achieve some specific structure for the coating. For instance, if you want rutile coatings, you should do a thermal treatment, so that you can get a complete transformation into this phase. Later on I hope to send you some other aspects that you can get once you make thermal treatment on a coating

Best regards

Oscar Gabriel Niño A.
Chemical Engineer
Universidad Nacional de Colombia
M. Sc. Process and Energy Engineering
Technische Universität Berlin
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wuji
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Quote wuji Replybullet Posted: 29 August 2004 at 9:08pm

i have one problem,the solution i prepared was stable during the very firt days,hovere after 2 days it begins to chang turbidity,ending up in the formation of a pale whit precipitates,please tell me the reason!

and i want to konw what is the mechanism of the peptization process?

 

thank you
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gabonino
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Quote gabonino Replybullet Posted: 30 August 2004 at 10:44am

wuji,

please contact me through e-mail, I got some articles regarding the peptization process. The change of the characteristics of the sol you preapre as time goes by might occur due to the aging process of the colloid, a very normal process in the lifetime of a sol. As titania tends to be a bit unstable, precipitates might form (I have seen this myself, sometimes they precipitate quickly, sometimes it takes a bit longer). A good thing to improve your sol shelf life could be a change in the pH of it. In this same forum, I think, someone actually recommended a change in the pH for a particular problem I had; I haven't been able to try, but you might want to contact this person, to ask how to change it.

Good luck, please let me know your results... I would really appreciate it,

Oscar Gabriel Niño A.
Chemical Engineer
Universidad Nacional de Colombia
M. Sc. Process and Energy Engineering
Technische Universität Berlin
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Soni
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Quote Soni Replybullet Posted: 03 September 2004 at 6:45am
What would be the following treatment of Mr. Prassas recipe to gain crystalline (anatase, rutile) TiO2-films? I am especially looking for treatments below 100°C. Thanks for your help.
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