We have prepared bulk Gd0.7Sr0.3MnO3 materials by conventional solid state reaction technique. Their corresponding nanoparticles were prepared by using ultrasonic energy. The lattice parameters for the bulk polycrystalline sample and corresponding nanoparticles prepared by ultrasonication are almost unaltered, however, the atomic positions are significantly different between the materials prepared by two different techniques. By using FULLPROF studio we have generated the structural view of Gd0.7Sr0.3MnO3 (a) bulk materials and (b) corresponding as shown in the attached figure. Is it realistic? Please let us know any expert opinion. Thank you very much in advance.
When you say that the atomic positions are significantly different, you determined their values from a structural refinement by Rietveld method? The XRD patterns differ only in the peak broadening? When a material is in form of nanoparticles I do not expect so high differencies in atoms coordination.
Dear Professor Marcella Bini,
Thank you very much for your reply. Yes, the atomic positions were determined from a structural refinement by Rietveld method using FullPROF package. yes, we are also surprised why such a high difference in atoms coordination. Would you please look again at the structure (a) and (b) and let us know any further suggestion.
This seems unlikely sir. Many a times due to refinement unrealistic parameters are obtained because the program knows only mathematics not crystallography or chemistry. It may be the case that some features of the XRD pattern were tried to be modeled by atomic positions but the features themselves were not related to actual atomic positional parameters; the features are due to some other parameters which were not refined. I personally think if the refinement procedure is carried out again, carefully avoiding unrealistic deviations in each step, a different convergence will be reached. Taking a look at the XRD patterns will perhaps help to diagnose the problem.
Would you mind to attach both raw XRD data? Nano particles shouldn't change that much compare to it bulk form. Seems like Gd and Sr not share the same wyckoff position. Also certain coordination seems odd.
I agree with Maykel, both structure plots look unrealistic. You should see something like this:
Thank you very much everyone. We understood, it was not correct. Now we are getting the structure correctly. Many many thanks for your expert opinion.
- Badges
- Science topic
- Similar topics
- Engineering
- Electrical Engineering
- Electrodes