Yes, The transformation of anatase to rutile depends on the particle size and preparation method also. Also I think the supporting materials also can play some role in the transformation bcos of local heating....but still converting rutile to anatase will be tricy and you have to try this using various particle size nanocrystalline tio2 and if you succeed in converting rutile TiO2 completely to anatase will be of great importance ...all the best...keep on updating...

There is literature stating that under certain conditions anatase becomes more stable than rutile for nanoparticles below some certain critical size. I am not aware of any work experimentally showing the backward transformation, I doubt that it is possible, but you could at least avoid the transformation to rutile by keeping your nanoparticles from growing large.

Dear Dr.Kubrin,

Thanks! The literature, for example: [DOI: 10.1021/jp000499j] in which it was found by isothermal and isochronal annealings, that thermodynamic stability of the anatase and brookite phases depend on the particle size. So, the particle size of less than 11 nm corresponds to stability of the brookite phase, for particle sizes between 11 nm and 35 nm, the stable phase is anatase and rutile is the most stable phase at the sizes greater than 35 nm. So, this way is avoiding the anatase to rutile transformation usually by limiting the temperature of the deposition process or/and postdeposition treatments.

I also have not seen any reports of ex situ transformation of rutile to anatase.

However, there could be direction(s) in which anatase just would provide better channeling of some ions. I mean the Ion Beam-Assisted Annealing. This way could provide an ex situ conversion.

By changing the anneling temperature we can change the phase of TiO2. From 450 to 600 C temperature gives anatase, after 600 it will start to change to rutile.

Dear Shwetha,

Please, read the question more careful.

p.s.

600 C is not the highest critical temperature of transformation, see the link attached.

https://www.researchgate.net/post/What_is_the_highest_possible_temperature_of_anatase_to_rutile_transformation_of_titanium_dioxide

It is very difficult to change the crystallite structure to anatase once rutile is formed.  However, if the grain size is very small, you could try and dope the surface and see if some local structural modification occurs 

Dear Dr.Revathi Ramachandran Bacsa,

Do you mean ex situ doping of nanosized rutile TiO2 crystals? What method does one want to use to do it? Any prerequisite?

I am not sure that it can done, but if you have crystals  that are really small, you can try sulfur doping that is known to favor the stabilisation  of anatase.  You can do this by heating the crystals in thio urea. this may create anatase on the surface. 

Dear Dr.Revathi Ramachandran Bacsa,

There is calculations(see the link above) showing that stability of anatase phase increases with decreasing the crystallite size. Annealing enlarges crystallites. 

However, an interesting experiment could be conducted. If TiO2 anatase crystallites were far away from each other(that probably possible by using very low concentration of precursor), what would be with the phase after annealing? If crystallites do not have a chance to agglomerate, up to what temperature anatase will be stable?

Nevertheless, it does not seem possible to transform rutile to anatase in a typical heat treatment.

i think your question is not correct...pl. go through liturature...the rutile is highly stable structure than anatase and it is obtained after calcination of anatase at higher temp more than 650 (approx) deg. and coversion of rutile to anatase may not be possible...till today i do not came across such ref.

Dear Dr.Rajesh Jagannath Tayade,

There are reports with the temperatures of the anatase-rutile transformation of more than 1000 C(see the link in this topic above).

Can you say for sure that rutile powder will not transform to anatase film during annealing the powder on an appropriate substrate?

Yes, The transformation of anatase to rutile depends on the particle size and preparation method also. Also I think the supporting materials also can play some role in the transformation bcos of local heating....but still converting rutile to anatase will be tricy and you have to try this using various particle size nanocrystalline tio2 and if you succeed in converting rutile TiO2 completely to anatase will be of great importance ...all the best...keep on updating...

Dear Rajesh Jagannath Tayade,

I will!

In [10.1021/ja044689] the method that allows to prepare anatase TiO2 crystals from rutile TiO2 powder via the wet-chemical process with the intermediate product Titanate was proposed.

http://pubs.acs.org/doi/abs/10.1021/ja044689%2B

Reversible sheet-to-tube transition and associated lattice transformation(nanosheet- rutile, nanotube- anatase) were obtained in [1] by deprotonation of titania nanosheets.

[1] Shaping Nanometer‐Scale Architecture Through Surface Chemistry,

Zoran Saponjic, Nada M Dimitrijevic, David M. Tiede, AJ Goshe, Xiaobing Zuo, Lin X. Chen // Advanced Materials (Impact Factor: 15.41). 04/2005; 17(8):965 - 971, DOI: 10.1002/adma.200401041 

Article Shaping Nanometer‐Scale Architecture Through Surface Chemistry

Yes, I converted Rutile to Anatase phase by multiple shock treatment for the first time, on subsequent shock treatment Anatase converted back to Rutile structure. I am in the process of finding the exact thermodynamic condition to convert Rutie TiO2 to Anatase TiO2 phase. However I am presenting a research paper on reversible phase transformation from Rutile to Anatase and back to Rutile (controllable ratio of mixed phase) in SAMPE 2016 symposium on 24th May 2016 at Long beach CA, USA.    

Hello,

Even i have the same question that whether Rutile to Anatase transition is possible under certain environment.

I am adding a reference from springer link by

Dorian A. H. Hanaor ,Charles C. Sorrell ,

Review of the anatase to rutile phase transformation

If we look at that the Gibbs energy vs Pressure plot, negative pressures would be required for Anatase to be more stable than Rutile. The transformation to Anatase thus is irreversible.

I am also curious of the concept of negative pressure.

Is there a way we can create an environment wherein negative pressure can be put into effect ?