To the best of my knowledge, Rietveld is the only statistically reliable method to obtain a quantitative distribution of mineral phases in complex systems, such as soils, cements etc. I know that there are some thermal methods (TGA, DTA) that require pure standards for quantitative analysis, which are not always available for complex materials. Please correct me if I am wrong, I deal with waste and heavy-metal contaminated soils and my experience with analytical techniques is limited to XRD, SEM, EPMA, XANES, FTIR and optical microscopy, so I am not be up-to-date with more sophisticated equipment.
Can anybody provide me with a good reference to support such a statement? I apply Rietveld quantitative analysis to assess the mineralogy of contaminated media, and I want to support the statement in a journal publication that this is the more statistically reliable of the available techniques, if one needs to look at a bulk sample (not focus on the nm scale). I also have a question on the accuracy of the method. I follow the discussions on the list and I would like to ask where you draw the line for a "good" and a "bad" refinement. Do you make a distinction between different types of materials and applications? My take is that I cannot expect to have an accuracy of 0.1% when I am dealing with samples that contain 10 phases and are bound to be subject to significant variability (such as waste and soils). I am happy if I have a 1-2% absolute error in the quantification and I do not even attempt to refine atomic positions or elemental substitutions. Can you give me your two cents on that? Maria Chrysochoou, Ph.D. W.M. Keck Geoenvironmental Laboratory Stevens Institute of Technology Tel.: +1 201 216 8773 Fax: +1 201 216 8212 E-mail: [EMAIL PROTECTED]
