PyXRD v0.6.7: a free and open-source program to quantify disordered phyllosilicates using multi-specimen X-ray diffraction profile fitting

Geoscientific Model Development

E.Van Ranst¹  M.Dumon¹ 

DOI  :  10.5194/gmd-9-41-2016

学科分类：天文学(综合)

来源: Copernicus Publications

【 摘 要 】

This paper presents a free and open-source program called PyXRD (short forPython X-ray diffraction) to improve the quantification of complex,poly-phasic mixed-layer phyllosilicate assemblages. The validity of theprogram was checked by comparing its output with Sybilla v2.2.2, whichshares the same mathematical formalism. The novelty of this program is theab initio incorporation of the multi-specimen method, making it possible toshare phases and (a selection of) their parameters across multiplespecimens. PyXRD thus allows for modelling multiple specimens side by side, andthis approach speeds up the manual refinement process significantly. Tocheck the hypothesis that this multi-specimen set-up – as it effectivelyreduces the number of parameters and increases the number of observations –can also improve automatic parameter refinements, we calculated X-raydiffraction patterns for four theoretical mineral assemblages. Thesepatterns were then used as input for one refinement employing themulti-specimen set-up and one employing the single-pattern set-ups. For allof the assemblages, PyXRD was able to reproduce or approximate the inputparameters with the multi-specimen approach. Diverging solutions onlyoccurred in single-pattern set-ups, which do not contain enough informationto discern all minerals present (e.g. patterns of heated samples). Assuminga correct qualitative interpretation was made and a single pattern exists inwhich all phases are sufficiently discernible, the obtained results indicatea good quantification can often be obtained with just that pattern. However,these results from theoretical experiments cannot automatically beextrapolated to all real-life experiments. In any case, PyXRD has proven tobe useful when X-ray diffraction patterns are modelled for complex mineralassemblages containing mixed-layer phyllosilicates with a multi-specimenapproach.

【 授权许可】

Unknown