KTaO3

[Probeman]

I'm attempting to analyze some trace elements in orthoclase and one of the traces I'm attempting is Rb.  The primary standard for this is the very nice RbTiOPO4 standard material described here:

https://probesoftware.com/smf/index.php?topic=301.msg2872#msg2872

However, I am running into a number of spectral interferences that need to be corrected, for example Rb is seemingly interfered by both Si and K. The interference standard for Rb interfered by Si is easy, SiO2, but finding an interference standard for Rb interfered by K is harder, since almost anything I can find that contains K, also contains Si, and one can't use a standard for an interference correction that contains additional interfering elements.

Searching through my standard database one material standards out, a KTaO3 standard that I got from Lynn Boatner from Oak Ridge many years ago, but it doesn't seem to be mounted in any of my standard blocks and looking through my standard stash I can't seem to locate any of the original material.

Does anyone have this KTaO3 material, or perhaps another K containing material that doesn't also contain Si?

[Anette von der Handt]

MTI seems to have it: https://www.mtixtl.com/ktao3.aspx but its somewhat pricey. It does seem to be a popular material for study in the material sciences though, maybe see if there is someone at your place that works with it?

I think I have KCl and KBr but I am not sure if you want to go down that route. There are various minerals that contain K but not Si (very useful tool for this http://athena.unige.ch/athena/mineral/search.html) but I am not sure if they would make a good interference standard either.

[Brian Joy]

However, I am running into a number of spectral interferences that need to be corrected, for example Rb is seemingly interfered by both Si and K. The interference standard for Rb interfered by Si is easy, SiO2, but finding an interference standard for Rb interfered by K is harder, since almost anything I can find that contains K, also contains Si, and one can't use a standard for an interference correction that contains additional interfering elements.

Usually I use PET to analyze for Rb; interferences from Si Kα and K Kα(2) are not a problem.  Can you not do this on the SX-100?  I can't remember.  At any rate, KTiOPO₄ might work well as a standard.  I have the materials to synthesize it.  Should I give it a try?

[Anette von der Handt]

Brian, I think the answer to this question is always "yes" 

[Probeman]

However, I am running into a number of spectral interferences that need to be corrected, for example Rb is seemingly interfered by both Si and K. The interference standard for Rb interfered by Si is easy, SiO2, but finding an interference standard for Rb interfered by K is harder, since almost anything I can find that contains K, also contains Si, and one can't use a standard for an interference correction that contains additional interfering elements.

Usually I use PET to analyze for Rb; interferences from Si Kα and K Kα(2) are not a problem.  Can you not do this on the SX-100?  I can't remember.  At any rate, KTiOPO₄ might work well as a standard.  I have the materials to synthesize it.  Should I give it a try?

That's a good question and CalcZAF can answer it:



So, technically the peak position is just barely inside the Cameca spectrometer limit (~83800), but the high off-peak position won't be inside the limit, so no the Cameca cannot really do Rb La on a PET crystal. Though I guess one could go with "same side" off-peaks:

https://probesoftware.com/smf/index.php?topic=68.msg6255#msg6255

and place both off-peaks on the low side and extrapolate, but then you've got the giant Si Ka line and its extended tails there interfering with the off-peak positions. But now I'm kind of actually enjoying the challenge of this interference correction!

Actually I've decided to start a new topic in the Probe for EPMA board on this trace analyses attempt in orthoclase because to be honest, I'm running in to other sorts of troubles and would appreciate any advice.

KTiOPO4 would be an excellent standard for this interference correction, but don't go to the trouble. First let me see if I can find it at ESPI or another source. If it's an industrial material it shouldn't be too expensive.

[Brian Joy]

However, I am running into a number of spectral interferences that need to be corrected, for example Rb is seemingly interfered by both Si and K. The interference standard for Rb interfered by Si is easy, SiO2, but finding an interference standard for Rb interfered by K is harder, since almost anything I can find that contains K, also contains Si, and one can't use a standard for an interference correction that contains additional interfering elements.

Usually I use PET to analyze for Rb; interferences from Si Kα and K Kα(2) are not a problem.  Can you not do this on the SX-100?  I can't remember.  At any rate, KTiOPO₄ might work well as a standard.  I have the materials to synthesize it.  Should I give it a try?

That's a good question and CalcZAF can answer it:



So, technically the peak position is just barely inside the Cameca spectrometer limit (~83800), but the high off-peak position won't be inside the limit, so no the Cameca cannot really do Rb La on a PET crystal. Though I guess one could go with "same side" off-peaks:

https://probesoftware.com/smf/index.php?topic=68.msg6255#msg6255

and place both off-peaks on the low side and extrapolate, but then you've got the giant Si Ka line and its extended tails there interfering with the off-peak positions. But now I'm kind of actually enjoying the challenge of this interference correction!

Actually I've decided to start a new topic in the Probe for EPMA board on this trace analyses attempt in orthoclase because to be honest, I'm running in to other sorts of troubles and would appreciate any advice.

KTiOPO4 would be an excellent standard for this interference correction, but don't go to the trouble. First let me see if I can find it at ESPI or another source. If it's an industrial material it shouldn't be too expensive.

So it's almost like you're saying that JEOL spectrometers might be better than CAMECA spectrometers for certain tasks??    I can also flip crystals during an analysis, and reproducibility of peak positions is fine (I've tested it ad nauseum).  KTP shouldn't be too difficult to find; it's used widely in laser optics.  I'll probably try growing it anyway.

[Probeman]

So it's almost like you're saying that JEOL spectrometers might be better than CAMECA spectrometers for certain tasks??    I can also flip crystals during an analysis, and reproducibility of peak positions is fine (I've tested it ad nauseum). 

Yeah, almost.   

If you're throwing down the gauntlet, let's see some numbers!  I've posted the spectro reproducibility testing specifications here that I used for the original acceptance tests on my SX100 (and again 5 years later):

https://probesoftware.com/smf/index.php?topic=210.msg8117#msg8117

Dude. Gimme data.   

Note to all: to see the JEOL vs. Cameca board you need to be logged in as a member...

[Probeman]

John - Ta M-alpha is at ~28200 on TAP, so KTaO3 may actually cause more problems than it solves. If you're buying from MTI, that KH2PO4 might be a better option, provided the tail from the P Ka isn't too long. MTI doesn't have KTP, which would probably be better (Ti Kb III might be a bit of an issue), but there's about a hundred laser supply places that do. Most of them don't list prices, but Newlight Photonics (http://www.newlightphotonics.com/Nonlinear-Optical-Crystals/KTP-Crystals) looks pretty cheap.

Not associated with any of these companies, etc.

Dang.  Good point.  Thanks for the heads up!