Stacking faults and clays?

rowlesmr

Hi all

Does anyone know of anyone who has used stacking fault models to look at interstratified clays?

Matthew

rowlesmr

Just reading some BGMN papers.

.

In Topas, you can define sx, sy, sz as stacking fault vectors to displace each layer. Is there any way to refine a rotation of a layer about the stacking direction?

johnsoevans

Hi Matthew. I would have recommended the Kristian Ufer and related papers, but you've clearly found those! I don't think you can specify a rotation explicitly. You can, of course, define various rotated layers.

karsten

Hi,

if the layers can be considered isolated (ignoring the basal reflection) a single layer in a partially empty supercell may do the trick. I once did a refinement for smectite and it also works fine for nanocrystalline calcium silicate hydrates. https://doi.org/10.1107/S1600576721012668

Jandrix1369

Related to this, I found the "Stacking Faults" Tutorial in the "Misc" files within the TOPAS directory. I use JEdit but without a tutorial on how to properly interpret and analyse these files, I've put quite a timesink into this in trying to understand... so my questions are:

1: Can the Stacking Faults kaolinite tutorials be adapted for other clays such as illite and muscovite? This is one of my primary works at the moment in trying to distinguish the two for a better refinement. I see the stacking faults scripts work well for refining kaolinite without having to mess around with complex site information (which may not even yield accurate results).

2: Are there any good tutorials regarding the Stacking Faults work on TOPAS/JEdit I can follow?

johnsoevans

The only tutorials I know of are: https://topas.webspace.durham.ac.uk/tutorial_stacking_faults/

These only describe the basics of how to set things up in TOPAS as a starting point. I don't work on clays so have never had a science driver to put other tutorials together. If other people want to prepare tutorials, they could be put on the wiki.

For me, developing appropriate models for complex systems like this sits in the realm of research so needs expert time-on-task.