It is known that bulk materials and thin films represent two different universes in terms of diffusion controlled transformations. Are commonly used phase diagrams, mainly made using bulk materials investigations, can find application in the exploration of thin films?
Dear colleagues, what is your opinion on this topic?
Dear Krzysztof, I would recommend to check the work from Helmut Dosch and coworkers about matter in confined geometries (i.e. thin films or nanomaterials), check e.g. the short review in Applied Surface Science 182 (2001) 192, doi: 10.1016/S0169-4332(01)00426-3, and references therein to get a first idea about the models, important parameters and resulting (critical) phenomena! Certainly, there is plenty more information available, but I think that this is a quite good first step into the matter! Good luck, Dirk
It is an interesting question, however if phase diagram behavior depends of the thickness of the material, then they will be infinite phase diagrams for a compound, something that sounds to me difficult to admit.
Dear Krzysztof Wieczerzak
In my opinionو one should expect differences in phase diagrams between bulk materials and thin films since non equilibrium amorphous phases exist in thin film may not found in the equilibrium phase diagram. The formation of amorphous phases as a result of massive reduction in temperature experienced by deposit atoms on arrival on substrate, as well as the relatively low mobility of deposit atoms on the surface which in turn hinder the re-arrangement of atoms into the equilibrium crystal structure.
Best regards
A typical phase diagram depends on temperature, pressure and composition (concentration). For sure, you must expect variation in phase diagram for the a bulk and thin film since effect of these three variables in the difference medium will differ. You may like to read the 8th edition of Atkins physical chemistry.
In addition to the main parameters (e.g., temperature, pressure and phase composition) of phase diagram, you might need to correct the XRD intensities due to the effect of crystallographic preferred orientation.
All depend from properties of materials: may be can maybe not.
Need check, and possible make methode to validate.
Good luck, Alex.
By processes implying low temperature (i.e. Pvd or electrodeposotion) you can obtain alloys not predicted by phase diagrams (that are constructed for equilibrium conditions). These alloys are not thermodynamically stable. So if you increase the temperature, they can decrease their excess of energy and you obtain a thin film exactly composed of the phases predicted by the phase diagram of the bulk material. It happens at ambiant temperature with thin film of gold deposited on copper. With ageing, the copper and gold diffuse and at the end your (cheap) watch becomes pink.
Commonly used phase diagram of materials demonstrates phase transformation of a given chemical composition as a function of temperature at equilibrium. The state of equilibrium is governed by diffusion controlled process. Thus it may be well understood that there will be a difference in phase diagram between the bulk and thin material under ambient condition.
Yes you should, if there is no amorphous or meta-stable crystalline phase, there will be certainly extension of solid solubility of thin film over the bulk.
For nano grained of binary alloys, which are meta stable, the temperature needed to produce a change in the phases is reduced due to the amount of energy stocked in the layer. The more metastable the alloy is the less energy you need to promote phase changes. In that point of view, there is a shift in the phase diagram. But when the changement is total, the result becomes a stable alloy which follows the diagram of the bulk.
It is very interesting question for researchers and scientists. Bulk materials are preparing in one method and thin films are preparing in different methods. Both are different and its depends on the thickness of the samples. I think also depends on the oxidation pressure, temperature, processing time and particle/grain.
Wish you good luck.
Hi dear Krzysztof
As I know and studied, because of severe effect of surface tensions in that scale and resulting tensions on lattice, it is so possible to moving phase stability regions in phase diagrams an in some cases forming different phase. I had seen some cases in articles.
I hope this answer can be useful to you.
Be succeed and best regards.
Dear colleagues, thank you for your comments on the topic and especially for recomendation of very interesting literature.
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