Recenly, I have prepared TiO2 film by a sol-gel method . Then, I use the tapping mode of AFM to characterize this film. The film is relatively uniform in morphology with surface roughness less than 20 nm. From the phase imaging of AFM, I have observed that there are two different phase areas in this film. I want to know what information I can get from this obsevation, the crystal phase difference?
In fact, my TiO2 film is calcined at 550 centigrade which is a transformation temperature of TiO2 from anatase phase to rutile phase. Therefore, I guess the two different phase areas observed in the AFM pahse diagram may be correspoding to the anatase phase and rutile phase. However, I am not very sure if this analysis is correct or not. Can anyone help me?
Thanks!
Dear Dawei Li, what do you mean by "phase diagram" and by "two phases"? I would believe that this relates the phase relation between excitation for tapping and response. So, you are getting two mechanically different kinds of interactions between tip and sample, depending on tip location on the sample. Is that correct?
Now I would try to correlate this information with your topology and some other microscopic information (SEM, for example) to obtain an idea to what kind of scale this belongs in your specimens.
Furthermore, I'd say that a corrugation scale of 20nm might be considered pretty rough, but this also depends on the lateral scale on which these elevations occur. After all i have heard and learned about AFM in recent years, the tapping mode is a rather crude kind of measurement, not quite gentle to your specimen.
Dear Dawei Li, what do you mean by "phase diagram" and by "two phases"? I would believe that this relates the phase relation between excitation for tapping and response. So, you are getting two mechanically different kinds of interactions between tip and sample, depending on tip location on the sample. Is that correct?
Now I would try to correlate this information with your topology and some other microscopic information (SEM, for example) to obtain an idea to what kind of scale this belongs in your specimens.
Furthermore, I'd say that a corrugation scale of 20nm might be considered pretty rough, but this also depends on the lateral scale on which these elevations occur. After all i have heard and learned about AFM in recent years, the tapping mode is a rather crude kind of measurement, not quite gentle to your specimen.
Dear Kai Fauth, thanks for your kind reply.
The "phase giagem" here means "pahse imaging". Your explanation is correct.
However, what I really want to know is that is there any relation between "phase imaging distribution difference" and "crystal phase distribution difference" for our TiO2 film or related films.
It is unlikely you can know this a priori. You will have to find out for your kind of specimens. Unlike the case when you work with macroscopic single crystals and where a high level of reproducability can be achieved (and therefore you might be able to more universally classify the relation between tapping/non tapping (->e.g. non contact tuning fork measurements, see the profile of F.-J. Giessibl) response and surface properties (differences in surface termination, for example)), this is very much specimen and preparation dependent in samples with nanoscale constituents.
Based on this personal prejudice, my prediction is that you will not get an easy answer to your question. Rather, the answer shall have to be elaborated by your research. If you get a conclusive result, then the signatures you found may serve as a powerful characterization tool.
It may be, however, that other researchers have encountered effects like the one you describe and will share their findings or opinions. You should nevertheless not adopt these interpretations without cross-checking for being reasonable or true in your specific specimens.
Based on my experiences in identifying the two phases of TiO2, I suggest to use AFM linked with Micro Laser Raman spectroscopy to identify the phases of Anatase and Rutile. SEM is also another alternative in identifying the morphology, but this depends on the film preparation and thickness...
Raman-AFM Combinations
By combining Raman spectral imaging with AFM, it is possible to link the molecular information obtained by confocal Raman spectroscopy with the ultra-high spatial and topographical information acquired by AFM.
So, it seems never the reference was shared. But has anyone here found?
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