Re: Millisite crystal structure?
I was afraid of that. Unfortunately, my sample is a powder containing about 3 or 4 different alkali phosphates, so a little tricky. On Tue, 24 Dec 2024, 15:51 Alan W Hewat, wrote: > Current (2023) knowledge, including main x-ray lines, is summarised on > https://www.mindat.org/min-2712.html > which also links to the extensive American Mineralogy database (which does > not include Millisite). If you have a clean sample, you may need neutrons > to distinguish it from similar hydrated minerals, but it's not obvious that > it's interesting enough :-) > Alan > > Dr Alan Hewat, NeutronOptics > Grenoble, FRANCE (from phone) > alan.he...@neutronoptics.com > +33.476984168 VAT:FR79499450856 > http://NeutronOptics.com/hewat > ___ > > > On Tue, 24 Dec 2024, 04:49 Matthew Rowles, wrote: > >> Hi all >> >> Does anyone know of a published crystal structure for millisite? >> >> It is nominally (Na,K)CaAl6(PO4)4(OH)9·3H2O >> Tetragonal, a=7, c=19.07 Å >> See http://www.minsocam.org/ammin/AM45/AM45_547.pdf >> >> >> or maybe anything possibly isostructural/morphous? It's pretty close to >> wardite, but has an extra hydroxide and water. >> >> ICDD PDF4+ has nothing, Various searches on COD haven't revealed >> anything. I don't have access to ICSD. >> >> Thanks >> >> >> Matthew Rowles >> ++ >> Please do NOT attach files to the whole list > > >> Send commands to eg: HELP as the subject with no body >> text >> The Rietveld_L list archive is on >> http://www.mail-archive.com/rietveld_l@ill.fr/ >> ++ >> >> ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: Millisite crystal structure?
Ta a lot Stephan I'll have a shot at that Thanks Matthew On Thu, 26 Dec 2024, 17:56 Stefan Seidlmayer, wrote: > Dear Matthew, > > it seems that based on this article from the 70s the Millisite structure > should definitely be a subgroup of the wardite structure. > Thankfully the wardite has been quite unambigously determined recently by > high-quality neutron single crystal xrd (ICSD#13007) > > Based on this and the similarity of the formula I would suggest to use a > transition which splits the Na 4a site in two, the simplest step would be > to use C2221 (#20) and then replace additional Na site with Ca and look for > the exchange of one H2O position to OH. > > I hope this helps. If you have good XRD data a refinement of the > substituted wardite structure model might prove my derivation. > > Best regards and a happy new year. > > Stefan Seidlmayer > > > Am Di., 24. Dez. 2024 um 04:49 Uhr schrieb Matthew Rowles < > rowle...@gmail.com>: > >> Hi all >> >> Does anyone know of a published crystal structure for millisite? >> >> It is nominally (Na,K)CaAl6(PO4)4(OH)9·3H2O >> Tetragonal, a=7, c=19.07 Å >> See http://www.minsocam.org/ammin/AM45/AM45_547.pdf >> >> >> or maybe anything possibly isostructural/morphous? It's pretty close to >> wardite, but has an extra hydroxide and water. >> >> ICDD PDF4+ has nothing, Various searches on COD haven't revealed >> anything. I don't have access to ICSD. >> >> Thanks >> >> >> Matthew Rowles >> ++ >> Please do NOT attach files to the whole list > > >> Send commands to eg: HELP as the subject with no body >> text >> The Rietveld_L list archive is on >> http://www.mail-archive.com/rietveld_l@ill.fr/ >> ++ >> >> ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
