General EPMA > EPMA Standard Materials
NIST Standards!
John Donovan:
This topic will be focused on the NIST (previously NBS) quantitative standard reference materials (SRM) standards and all associated issues related to obtaining, mounting, characterizing, utilizing, etc., etc., etc.
I will make it "sticky" so it will always be available for newcomers. Let me know if anyone has other suggestions. :)
Probeman:
OK. I'll start this thread off with a comment about the NBS (NIST) mineral glasses which as we all know have had further characterization performed more or less informally by various labs, so here's my lab's contribution:
Here's the output from my standard database for both standards:
St 160 NBS K-412 mineral glass
TakeOff = 40.0 KiloVolt = 15.0 Density = 2.600
SRM 470, NIST
C.M. Taylor (Photometry?) FeO 2.77, Fe2O3 8.15
Total as FeO 10.10, Excess O 0.815
Na = 430 PPM (EPMA by JJD)
Oxide and Elemental Composition
Average Total Oxygen: 43.597 Average Total Weight%: 100.120
Average Calculated Oxygen: 42.797 Average Atomic Number: 12.694
Average Excess Oxygen: .800 Average Atomic Weight: 21.981
ELEM: SiO2 FeO MgO CaO Al2O3 MnO O Na2O
XRAY: ka ka ka ka ka ka ka ka
OXWT: 45.352 9.960 19.331 15.250 9.270 .099 .800 .058
ELWT: 21.199 7.742 11.657 10.899 4.906 .077 43.597 .043
KFAC: .1621 .0654 .0776 .1008 .0334 .0006 .1738 .0002
ZCOR: 1.3079 1.1840 1.5025 1.0818 1.4676 1.2046 2.5078 1.9910
AT% : 16.571 3.044 10.530 5.970 3.992 .031 59.822 .041
24 O: 6.648 1.221 4.224 2.395 1.601 .012 24.000 .016
St 162 NBS K-411 mineral glass
TakeOff = 40.0 KiloVolt = 15.0 Density = 2.600
SRM 470, NIST
C.M. Taylor (Photometry?) FeO 4.39, Fe2O3 11.23
Total as FeO 14.49, Excess O 1.12
Oxide and Elemental Composition
Average Total Oxygen: 43.558 Average Total Weight%: 100.183
Average Calculated Oxygen: 42.438 Average Atomic Number: 13.227
Average Excess Oxygen: 1.120 Average Atomic Weight: 22.412
ELEM: SiO2 FeO MgO CaO Al2O3 MnO O
XRAY: ka ka ka ka ka ka ka
OXWT: 54.301 14.420 14.671 15.471 .100 .099 1.120
ELWT: 25.382 11.209 8.847 11.057 .053 .077 43.558
KFAC: .2018 .0950 .0568 .1027 .0004 .0006 .1735
ZCOR: 1.2577 1.1793 1.5585 1.0769 1.4586 1.2001 2.5106
AT% : 20.217 4.490 8.143 6.172 .044 .031 60.903
24 O: 7.967 1.769 3.209 2.432 .017 .012 24.000
Right off you'll note that I've got some FeO/Fe2O3 data so you'll see that there is some "excess oxygen", that is, not all the Fe is as FeO.
Secondly, you will note that there are some trace elements (Na and Mn) that have been documented by several labs. What does your lab obtain for trace impurities in these NBS (NIST) glasses?
Thirdly, are these glasses still available on the open market? They are terrific.
Anette von der Handt:
Hi,
I haven't mounted them yet but I am about to, then I can add to your second point. In regard to your third question, my lab got the K-411 as glass microspheres a few years ago so they should be still available. I found the glass shards online listed at SPI supplies as part of their "30 glasses mounts". I got both as glass shards as a generous gift from John Fournelle. He also recommended them to me as standards for pyroxene analysis.
John Donovan:
Also check this discussion of mounting the Smithsonian standards which also come in tiny fragments in very small vials:
http://probesoftware.com/smf/index.php?topic=172.0
Probeman:
In the NIST K-411 and K-412 mineral glasses, one of them (K-411) is not certified for aluminum as it is apparently a zero concentration. I've never looked closely at trying to measure it myself, but I always see a few hundred PPM of Al in K-411 when measuring Al.
Has anyone made a more serious effort to characterize the NIST K-411 mineral glass for Al?
john
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