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From: Paritosh W. <par...@gm...> - 2024-08-23 09:51:19
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Hello Rajesh, Interesting fittings but if I am right you have deposited your thin films using pulsed laser deposition right ? Paritosh On Fri, Aug 23, 2024, 6:18 PM Dutta, Rajesh via xrayutilities-users < xra...@li...> wrote: > Dear Dominik, > > > > Many thanks for the fruitful hints. It is doable somehow even though it is > orthorhombic system on top of cubic. Luckily, our SrFeO2.5 (5.6, 5.65, > 15.7A) can be treated as pseudocubic system (rotating 45 deg around > c-axis). With this setting a,b axes of SrFeO2.5 become like cubic > SrTiO3(3.905A). However, I had to manually build both the SrTiO3 and > SrFeO2.5 to match the c-axis and to incorporate elastic constants as well. > Please have a look at the attached figure (simulation and experimental > data). Let me know your thoughts. > > > > Besides that, I have questions: (1) Only multibeam kinematical model takes > all the reflections using “surface_hkl=(0,0,1)” where others take only one > given (H, K, L). Is there any way to make a list for (H,K,L) so that other > model can calculate the XRD for several (H,K,L). I tried to give a list but > did not work. (2) Is the relaxation parameter treated as strain/stress > here? If not, how can I input in-plane stress or strain? I will try to fit > the data and let you know the outcomes. > > > > Thanks again, > > Bye, > > Rajesh > > > > *From:* Dominik Kriegner <dom...@gm...> > *Sent:* Thursday, August 22, 2024 5:46 AM > *To:* Dutta,Rajesh <rd...@dr...> > *Cc:* xra...@li... > *Subject:* Re: [Xrayutilities-users] XRD-Simulation needs elastic > parameters > > > > *External.* > > Dear Rajesh, > > > > Is there a standardized way the elastic parameters are provided in the cif > files? If so one could update the parser to allow to read it properly. > > > > But likely it's better you define the materials manually. I recommend you > to look at > > https://xrayutilities > .sourceforge.io/examples.html#using-the-materials-subpackage > > I am however afraid I did not include some documentation on how to add the > elastic parameters. For this maybe best look at how it is done for the > predefined materials in the code > > https://github.com/dkriegner/xrayutilities/blob/main/lib/xrayutilities > /materials/predefined_materials.py > > > > Finally I must warn you that I do believe that the pseudomorphic stack was > never tested for orthorhombic materials on top of a cubic material. I am > almost certain it won't exactly do what you expect. > > You might be able to help yourself and distort the material as you see > fit, but I would not rely on the pseudomorphicstack code to work without > changes! > > > > cheers > > Dominik > > > > On Thu, Aug 22, 2024 at 2:21 AM Dutta, Rajesh via xrayutilities-users < > xra...@li...> wrote: > > Dear xrayutilities users, > > > > I am very new to this tool. I am trying to build a layer stack of Sr2Fe2O5 > (ortho) on top of SrTiO3 substrate (cubic). I managed to construct the > model using cif files. However, in the cif file seemingly it is not > possible to incorporate cij (elastic parameters). Therefore, the fitting > XRD gives an error saying “layer’ argument needs elastic parameters. > > > > How to solve this issue while importing cif files. I attach few parts of > the code below: > > > > # global parameters > > wavelength = xu.wavelength('CuKa1') > > offset = -0.00 # angular offset of the zero position of the data > > > > # set up LayerStack for simulation: SrTiO3/SrFeO2.5 > > Sr = xu.materials.elements.Sr <http://xu.materials.elements.sr/> > > Ti = xu.materials.elements.Ti > > O = xu.materials.elements.O > > Fe = xu.materials.elements.Fe > > STO = xu.materials.Crystal.fromCIF(os.path.join("data", "STO.cif")) > > SFO = xu.materials.Crystal.fromCIF(os.path.join("data", > "Sr2Fe2O5-along.cif")) > > > > lSTO = xu.simpack.Layer(STO, inf) > > lSFO = xu.simpack.Layer(SFO, 800, relaxation=0) > > > > pstack = xu.simpack.PseudomorphicStack001('list', lSTO, lSFO) > > > > # set up simulation object > > thetaMono = arcsin(wavelength/(2 * xu.materials.Ge.planeDistance(2, 2, 0))) > > Cmono = cos(2 * thetaMono) > > dyn = xu.simpack.DynamicalModel(pstack, I0=1.5e5, background=0, > > resolution_width=2e-3, polarization='both', > > Cmono=Cmono) > > fitmdyn = xu.simpack.FitModel(dyn) > > fitmdyn.set_param_hint('SFO_a', vary=True, min=15.7, max=15.8) > > fitmdyn.set_param_hint('STO_a', vary=True, min=3.90, max=3.91) > > fitmdyn.set_param_hint('resolution_width', vary=True) > > params = fitmdyn.make_params() > > > > I tried to build the materials using Crystal class and SGLattice, there I > can define elastic tensors but it does not account proper Wyckoff > positions, this is why I used cif files. > > > > Any help, please let me know if you need more info. > > > > Thanks, > > Rajesh > > > > *-------------------------------------* > > *Dr. Rajesh Dutta* > > > *Research Staff Scientist Drexel University College of Engineering > Pronouns: he/his/him* > > Drexel University > 3100 Market Street > <https://www.google.com/maps/search/3100+Market+Street+%0D%0APhiladelphia,+PA+19104?entry=gmail&source=g> > Philadelphia, PA 19104 > <https://www.google.com/maps/search/3100+Market+Street+%0D%0APhiladelphia,+PA+19104?entry=gmail&source=g> > drexel.edu > > -------------------------------------------- > > > > _______________________________________________ > xrayutilities-users mailing list > xra...@li... > https://lists.sourceforge.net/lists/listinfo/xrayutilities-users > > _______________________________________________ > xrayutilities-users mailing list > xra...@li... > https://lists.sourceforge.net/lists/listinfo/xrayutilities-users > |
