Dear experts on Rietveld with x-ray,
When it comes to Rietveld, I have exclusively been working with neutrons. Now I am just trying Rietveld with x-rays, and immediately came up with a question. Since x-ray scatters from electrons, it seems to me that we always have to use, for instance, O-2 instead of O, and so on, for ionic compounds. But I have an impression that O is still used in many examples, including certain example files given in GSAS, such as Y2O3.EXP. Why is it? As a naturally following question, since no material is perfectly ionic, the oxidation numbers may become another "refinable" parameters. But I suppose they are never refinable in GSAS or in FullProf. Therefore, I suppose the fractional occupation may be compromised instead? Is this in any way discussed among x-ray experts? Thanks a million in advance. Jae-Ho *********************************************** Jae-Ho Chung, Assistant Professor Department of Physics, Korea University Anam-dong 5, Seongbook-gu Seoul 136-713, Rep. of Korea tel.) +82-2-3290-3116 fax.) +82-2-927-3292 web.) <http://scattering.korea.ac.kr> http://scattering.korea.ac.kr ***********************************************
