CsTiOAsO4 ("CTA") as a potential Cs standard

[Probeman]

This is getting very interesting!

[Brian Joy]

An advantage of having two potential standard materials for a given element is the ability to cross-check them; this is made especially convenient when the matrix corrections are small.  When I analyze my most recent batch of CsNbOB₂O₅ for Cs using my most recent batch of CsTiOAsO₄ as the standard, I get the results below when analyzing 35 spots.  I’ve fixed wt% Nb₂O₅ and wt% B₂O₃ at the respective stoichiometric values.  Likewise, I’ve assumed that the CsTiOAsO₄ is stoichiometric.

PAP/MAC30:


Armstrong/FFAST:


The small difference in atomic number correction between the two models accounts fully for the small difference in results.  Further, the results suggest that both compounds are pure and stoichiometric or very nearly so.

EDIT:  I just completed a set of wavelength scans on my most recent batch of CsTiOAsO₄, and they reveal a minute Ca Kα peak corresponding to less than 500 ppm CaO.  I'd noted the presence of Ca in the remnants of the flux that got into the mount; I'm not sure where it came from, but it doesn't appear to have contaminated the CTA significantly.  The small peak near 151 mm on LiFH is Cs Lγ₄.  I'm not certain of the identity of the peak at 180.3 mm on LiFH and at 83.05 mm on PETL (it also shows up on a scan on a CTA crystal from another batch); it is not Zn Kβ(2) and is likely to be a minor Cs peak, perhaps Cs Lβ₆.

[Probeman]

EDIT:  I just completed a set of wavelength scans on my most recent batch of CsTiOAsO₄, and they reveal a minute Ca Kα peak corresponding to less than 500 ppm CaO.  I'd noted the presence of Ca in the remnants of the flux that got into the mount; I'm not sure where it came from, but it doesn't appear to have contaminated the CTA significantly.  The small peak near 151 mm on LiFH is Cs Lγ₄.  I'm not certain of the identity of the peak at 180.3 mm on LiFH and at 83.05 mm on PETL (it also shows up on a scan on a CTA crystal from another batch); it is not Zn Kβ(2) and is likely to be a minor Cs peak, perhaps Cs Lβ₆.

Did you check the NIST x-ray database in Probe for EPMA?  It's pretty complete. Try a scan in PFE and plot up those elements and see what it shows.
john

[Brian Joy]

EDIT:  I just completed a set of wavelength scans on my most recent batch of CsTiOAsO₄, and they reveal a minute Ca Kα peak corresponding to less than 500 ppm CaO.  I'd noted the presence of Ca in the remnants of the flux that got into the mount; I'm not sure where it came from, but it doesn't appear to have contaminated the CTA significantly.  The small peak near 151 mm on LiFH is Cs Lγ₄.  I'm not certain of the identity of the peak at 180.3 mm on LiFH and at 83.05 mm on PETL (it also shows up on a scan on a CTA crystal from another batch); it is not Zn Kβ(2) and is likely to be a minor Cs peak, perhaps Cs Lβ₆.

Did you check the NIST x-ray database in Probe for EPMA?  It's pretty complete. Try a scan in PFE and plot up those elements and see what it shows.
john

Hi John,

Just before I left California in 2011, I wrote a program to search for interferences among X-rays because I was frustrated with the number of X-ray lines that were missing from the PeakSight database.  When I wrote this program, I lifted the old NIST X-ray database from CalcZAF since it was much more complete and included satellites.  So this is what I generally use to identify more obscure X-ray lines, as I can search by a number of different means (list all X-rays and reflections up to specified order produced by a given element, list all potentially interfering X-rays and reflections for a given set of elements near a selected X-ray of interest, list all X-rays and reflections near a given sine(θ) value).  However, the peak at ~180.3 mm on LiF is not present in that database.  When I look at other wavelength scans of Cs compounds that I’ve grown, the peak is always present, and so it is almost certainly due to Cs; the position of the peak suggests that it is one of the Lβ lines.

But yes, you're right -- I should be collecting these scans in PfE so that I don't have to identify X-rays in a two-step process.  I'm slowly making the transition...

Brian