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:




On Wed, 16 Mar 2022 at 21:13, Matthew Rowles <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
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