Dear Jon,
It might be just me, my current QPA practise is to micronise all samples down to 10-40 micron range and make a flat sample surface for the machine to scan. I trust the SRMs are already fine enough and Matthrew packed them well. There are roughness correction models but they may be sample (particles size) dependant hence used scaresly in my QPA practise. I am not aware of any guideline of roughness models based on controlled QPA experiments, so I am just worry the roughness models could either under- or over- correct the QPA results. Cheers! -- Dr. Xiaodong (Tony) Wang Senior Research Infrastructure Specialist (XRD) Central Analytical Research Facility (CARF) | Queensland University of Technology Address: Level 6, P Block, Gardens Point campus, 2 George St Brisbane QLD 4000 Tel: +61 7 3138 1904 | Mob: 0452 571 680 Email: tony.w...@qut.edu.au | Web: www.qut.edu.au/ife/carf At 2022-04-13 18:09:53, "Jonathan WRIGHT" <wri...@esrf.fr> wrote: >Maybe a silly question: are you assuming you have the data on an absolute >scale >in order to do these calculations? Do things like surface roughness somehow >not >matter? > >Best > >Jon > > > > >On 13/04/2022 11:56, Matthew Rowles wrote: >> Thanks Tony >> >> When I add the absorption edge correction to the silicon nitride model (and >> add >> beta-silicon nitride), it becomes -2.8 wt% amorphous; up a little due to the >> added correction and down a little due to the extra phase. >> >> If I change your al-SN thermals from 1 to those given in ICSD 77811, I get >> +4.8 >> wt% amorphous. Your atoms were already neutral, so I left them as-is. >> >> If I make all the Si-nitride phases' thermal parameters == 0, then I can get >> up >> to 8.5 wt% amorphous. >> >> In all of this, corundum is staying as charged atoms, with Al and O beqs >> fixed >> at 0.334 and 0.278. >> >> I'll have to have a go at applying the absorption edge correction; I always >> forget which parameter is which thing and have to rederive my understanding >> of >> it everytime... >> >> >> Thanks >> >> Matthew >> >> On Wed, 13 Apr 2022 at 13:58, iangie <ian...@126.com >> <mailto:ian...@126.com>> wrote: >> >> Dear Matthew, >> >> I tried your data and get ~-1% amorphous. My .pro is in below link. >> >> https://www.dropbox.com/s/xuw13c91l9gq5m5/ROW.pro?dl=0 >> <https://www.dropbox.com/s/xuw13c91l9gq5m5/ROW.pro?dl=0> >> >> I normally do not refine Beq, which I believe gives biggest source of >> error >> in QPA... >> >> >> Cheers! >> >> -- >> >> *Dr. Xiaodong (Tony) Wang* >> *Senior Research Infrastructure Specialist (XRD)* >> Central Analytical Research Facility (CARF) | Queensland University of >> Technology >> *Address:* Level 6, P Block, Gardens Point campus, 2 George St Brisbane >> QLD 4000 >> *Tel:*+61 7 3138 1904 | *Mob:*0452 571 680 >> *Email:* tony <mailto:stephen.blank...@qut.edu.au>. >> <mailto:stephen.blank...@qut.edu.au>w...@qut.edu.au >> <mailto:stephen.blank...@qut.edu.au> | *Web:* www.qut.edu.au/ife/carf >> <http://www.qut.edu.au/ife/carf> >> >> >> At 2022-04-13 13:00:44, "Matthew Rowles" <rowle...@gmail.com >> <mailto:rowle...@gmail.com>> wrote: >> >> Hi all >> >> Thanks to those that have replied off-list. >> >> I've managed to jiggle things around and get various answers. If you >> want an answer between -14 and +6 wt% amorphous, I can make it >> happen. I >> can either use charged atoms or not, or use thermal parameters or >> not. >> Combining those between the corundum and Si3N4, you get the >> following: >> >> >> image.png >> This is using the scattering factors defined with 11 gaussians. >> >> If you use the ones defined by 9 gaussians, you get >> image.png >> >> The structures I used are below. In the certificate for 656, the >> structures are referenced, but those structures have no thermal >> parameters. Does anyone know what was used in the NIST determination? >> >> >> >> phase_name "Aluminium_oxide_alpha_10425_icsd" >> Hexagonal( 4.759355, 12.99231) >> space_group "R -3 c H" >> site Al1 num_posns 12x 0 y 0 z 0.14772 occ Al+3 1. beq 0.318 >> site O1 num_posns 18x 0.3064 y 0 z 0.25 occ O-2 1. beq 0.334 >> >> phase_name "ALPHA_Marchand_ICSD_26191" >> Hexagonal( 7.75411, 5.62034) >> space_group "P31c" 'atom positions from Marchand. Thermals from ICSD >> 77811 >> site Si1 num_posns 6x 0.0806 y 0.5095 z 0.3020 occ Si+4 1 beq 0.25 >> site Si2 num_posns 6x 0.1675 y 0.2560 z 0.0070 occ Si+4 1 beq 0.29 >> site N1 num_posns 2x 0 y 0 z 0 occ N 1. beq 0.88 >> site N2 num_posns 2x =1/3; y =2/3; z 0.3500 occ N 1. beq 0.46 >> site N3 num_posns 6x 0.0390 y 0.3860 z 0.0310 occ N 1. beq 1.06 >> site N4 num_posns 6x 0.3190 y 0.3210 z 0.2660 occ N 1. beq 0.17 >> >> phase_name "BETA_Billy_ICSD_35566" >> Hexagonal( 7.60633, 2.90778) >> space_group "P 63/m" ' structure from Billy, thermals from ICSD >> 170004 >> site Si1 num_posns 6x 0.2323 y 0.4096 z 0.25 occ Si+4 1 beq 0.231 >> site N1 num_posns 2x =1/3; y =2/3; z 0.25 occ N 1 beq 0.326 >> site N2 num_posns 6x 0.3337 y 0.0323 z 0.25 occ N 1 beq 0.314 >> >> >> >> >> >> >> On Tue, 12 Apr 2022 at 17:13, Matthew Rowles <rowle...@gmail.com >> <mailto:rowle...@gmail.com>> wrote: >> >> Hi all >> >> I've collected some more data, and am still getting spurious >> results, and by spurious, I mean -5 wt% amorphous in >> SRM-alpha-656 >> when quantified by the external method against SRM 676a. >> >> We had some SRM-656alpha (couldn't find any of the beta) stored >> in a >> drying oven, and some SRM676a stored in a cupboard. I collected >> some >> data using a D8 with Ni-filtered Cu and a lynx-eye detector >> (0.25° >> fixed divergence, 250 mm radius, 2x2.5° sollers). The patterns >> were >> collected consecutively (using the same program), with a single >> peak >> from SRM1976 (b, I think), acting as an intensity calibrant (the >> intensity didn't appreciably change), collected before, after, >> and >> between. >> >> Does anybody want to have a look at the data and see what I'm >> doing >> wrong? Data available at: >> >> https://raw.githubusercontent.com/rowlesmr/pdCIFplotter/changing-str-to-float-conversion/data/row_Cu_676a.xy >> >> <https://raw.githubusercontent.com/rowlesmr/pdCIFplotter/changing-str-to-float-conversion/data/row_Cu_676a.xy> >> >> >> https://raw.githubusercontent.com/rowlesmr/pdCIFplotter/changing-str-to-float-conversion/data/row_Cu_al656.xy >> >> <https://raw.githubusercontent.com/rowlesmr/pdCIFplotter/changing-str-to-float-conversion/data/row_Cu_al656.xy> >> >> >> Thanks >> >> Matthew >> >> >> >> >> >> On Wed, 16 Mar 2022 at 21:13, Matthew Rowles <rowle...@gmail.com >> <mailto:rowle...@gmail.com>> wrote: >> >> Hi List People >> >> Do any of you use NIST SRM656 in your quantitative analysis >> quality control? >> >> I've recently started at a new lab, and am finding it >> impossible >> to make a physically realistic model (in Topas) that gives >> results anywhere near correct (or at least, close to the >> certificate values). >> >> As an example, using the external std approach with SRM676, >> I've >> managed to calculate there is -11 wt% amorphous in the >> beta-656 >> standard. >> >> I've tried using the silicon nitride structures given in the >> SRM >> certificate, but the papers and the ICSD entries don't list >> any >> thermal parameters. >> >> I can get the same results as given on the certificate using >> a >> siroquant model, but I don't know the provenance of the HKL >> files used in the analysis. >> >> >> Thanks in advance >> >> >> Matthew Rowles >> >> >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> >> Send commands to <lists...@ill.fr> 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 <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> 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/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
