Hi, my research involves in ZnO synthesis. I have performed rietveld refinement of my samples and obtain a good fit using Fullprof suite software. However to obtain the crystallite size, the IRF file is required which often generated from the standards as LaB6, Si etc.,,, . May i know whether others standards (in my case, pure ZnO) be used to generate the IRF file since I have analyzed the pure ZnO sample with the same XRD instrument. I also have performed the rietveld refinement on the pure ZnO and obtain pretty much similar crystal parameter (lattice constants,...atom occupancies..etc.,,) with the standard ZnO sample from the cif files. Therefore, can i used the pure ZnO XRD pattern to generate the IRF file ?
It is tempting to use your existing ZnO data, but don't!
You really want a sample for which sample peak broadening is negligible, and there are so many ways to get broadening*, it is really important to have a NIST or other certified line breadth standard, not just line position.
*You might say, not so many ways, just crystallite size and microstrain effects. But there are lots of ways to introduce microstrain and it can be really hard to get rid of it all.
Yes, you can use pure ZnO to generate the Instrumental Response Function (IRF) file for Rietveld refinement, provided that the ZnO sample is well-characterized and its diffraction peaks are sharp and well-defined. Here are the key points to consider when using a standard like ZnO to generate the IRF file:
Requirements for a Standard
Steps to Generate IRF Using ZnO
Example Procedure in FullProf
In FullProf Suite, you can follow these general steps:
Considerations
- Consistency: Ensure that the same XRD instrument settings (e.g., slit sizes, detector settings) are used for both the standard and the samples being analysed.
- Validation: Validate the IRF by comparing the refinement results of known standards (like LaB6 or Si) to ensure accuracy.
Conclusion
Using pure ZnO as a standard to generate the IRF file is feasible if it meets the criteria for a good standard material. The key is to ensure that the ZnO sample is highly crystalline and well-characterised. This approach allows you to account for the specific instrumental broadening effects in your XRD setup, leading to more accurate crystallite size and microstrain measurements in your Rietveld refinements.
Although Joshua's answer is very nice, and demonstrates skill in using Chat GPT or Open AI, that answer was not written by a human.
Notice that the requirements for the standard mean that are somewhat vague but properly applied mean that you must have compared your local standard, such as ZnO, to a certified NIST SRM, or equivalent.
Notice the Validation point under considerations means that you must compare your local, secondar, standard to a well characterized primary standard! So, you really need NIST SRM 660 or 640.
If you have compared your ZnO to NIST SRM 660x or 640x and find identical peak widths (interpolated to the same angles), then sure, use your ZnO, but without that comparison, don't! (As I said more briefly, above.)
The point from Joshua about Consistency is very important: acquire your sample data and reference data using same settings and acquisition parameters (except possibly count time).
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