Poll

What Standard Should Be Developed Next?

Mg2SiO4 (Forsterite)
Fe2SiO4 (Fayalite)
UO2 (depleted)
ThSiO4 (Thorite or Huttonite)
CsZrOPO4
PbSiO3 (Alamosite)
Al2SiO4F2 (Topaz)

Author Topic: Standards Which Should Be Developed For EPMA Next  (Read 19025 times)

John Donovan

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Standards Which Should Be Developed For EPMA Next
« on: August 03, 2015, 02:59:24 PM »
Note: you must be logged in to see the poll results and/or to vote!

This is a popularity contest.  The most popular standard material will be developed next.

We're shooting for $100/gram for that are not water soluble and are beam stable. Please indicate your preference in the above poll.

Remember, our ability to develop this next standard depends on our "nest egg" funds from sales of the first "crowd sourced" RbTiOPO4 at $100/gram from The CalChemist site here:

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

Marc will need to purchase the starting raw materials from this "nest egg" for whatever standard is polled as next most desired.
« Last Edit: June 09, 2016, 10:03:44 AM by John Donovan »
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Marc Schrier

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #1 on: October 15, 2015, 06:03:25 PM »
Just out of curiosity, what's the interest in UO2?  Would another depleted oxide or phosphate work? -Marc

John Donovan

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #2 on: June 09, 2016, 08:38:13 AM »
Please (if you haven't already), vote in the standards to be developed next poll here (you must be logged in to vote and/or see the poll results!):

http://probesoftware.com/smf/index.php?topic=560.0

to help us identify the next candidate material for standard development.  More materials could be considered but it's at least a start...

So far 13 people (out of ~300 members) have voted.  It would be nice to get a more comprehensive sampling!

Thank-you!
« Last Edit: June 09, 2016, 10:05:06 AM by John Donovan »
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Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #3 on: June 23, 2016, 01:50:41 PM »
Bump.   ;D

Please vote in the standard material poll above if you haven't already.  Remember you have to be logged in to see the poll results or to vote.

http://probesoftware.com/smf/index.php?topic=560.0

john
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Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #4 on: June 28, 2016, 08:36:29 AM »
It's a close race between the top three standard candidate materials:

http://probesoftware.com/smf/index.php?topic=560.0

Remember you have to be logged in to see the poll results or to vote!
The only stupid question is the one not asked!

John Donovan

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #5 on: July 12, 2016, 03:43:32 PM »
By the way, I just had a nice chat with Julien Allaz, who as you may know is heading up the MAS FIGMAS effort (with Anette von der Handt and Owen Neill), to document our current standards and manage future efforts in developing new standards.

I just want to say for the record that I fully support their efforts and that our own efforts here to "jump the gun" and start thinking about new standards is just merely to "prime the pump" informally to get us all thinking and talking about opportunities for new, pure, robust and plentiful(!) standard materials for SEM and EPMA.

I would characterize the FIGMAS effort as the "formal" process, and our own small efforts a complementary "informal" process. My personal take is that although we absolutely need to document what we already have, before we can get really serious about new standards, we already know that there are specific elements in specific phases that we know we don't have any reasonable availability of.  For example Rb and Cs primary standards. That is why I was so happy to obtain the RbTiOPO4 standard material that the Calchemist site is now offering at $100/gram.

http://www.calchemist.com/standards.htm

Cheap and significant quantities of pure standard materials is the goal!

I should also add that I personally have no interest in a Cs standard (though it is leading in our informal poll at the moment), but I do know that what's out there for Cs are only very small (flyspeck) quantities, of relatively poorly characterized natural materials. And since we already have a recipe for a Cs zirconyl phosphate phase, it might be one candidate new standard. Maybe.

Frankly I'd personally be more interested in a pure end member fayalite (Fe2SiO4) for testing matrix corrections, but I think it should be a community decision... depending on the difficulty of preparation of course, hence the poll here:

http://probesoftware.com/smf/index.php?topic=560.0

In any case, I would expect that if the MAS or FIGMAS group decides to perform a survey on what standard to develop next, it will be much more complete survey, with better statistics (one would hope anyway!). But this simple poll is just one small attempt to begin to "test the waters" as they say!

Julien said he is still working on the FIGMAS web site but will post something here as soon as he can. We of course are all very interested in what the future will bring...
« Last Edit: July 12, 2016, 04:38:10 PM by John Donovan »
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crystalgrower

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #6 on: January 26, 2018, 11:09:28 AM »
Any combination of Cs and Zr and PO4 will give two phases:  CsZr2(PO4)3 as already reported, and CsPO3.  It is not a matter of heat or pressure, but cation radius. 

Now there is a reliable published synthesis for Cs4Ba(PO3)6 which yes has a lot of EDS overlaps.  Materials Research Bulletin vol 12 pages 13-16 in French. I would try Cs4Sr(PO3)6 using the same starting proportions and temperatures. 

There are also reliable syntheses for Th(PO3)4 and U(PO3)4 Any takers?

FYI all the metaphosphates that I have suggested are totally insoluble.  No colour centres when run on full scan XRF.  They polish very well.  They fit your cost profile.  The people who have purchased rare earth ultraphosphates can vouch for longterm electron beam stability of similar compounds. 

I know.  They ain;t silicates.
« Last Edit: January 26, 2018, 11:20:21 AM by crystalgrower »

Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #7 on: January 26, 2018, 11:20:25 AM »
Any combination of Cs and Zr and PO4 will give two phases:  CsZr2(PO4)3 as already reported, and CsPO3.  It is not a matter of heat or pressure, but cation radius. 

Now there is a reliable published synthesis for Cs4Ba(PO3)6 which yes has a lot of EDS overlaps.  Materials Research Bulletin vol 12 pages 13-16 in French. I would try Cs4Sr(PO3)6 using the same starting proportions and temperatures. 

There are also reliable syntheses for Th(PO3)4 and U(PO3)4 Any takers?

I'm interested in any high concentration Cs synthetic that is stoichiometric, non-water soluble and beam stable.  The RbTiOPO4 is perfect is all these respects, but according to Marc Schrier there is no Cs analog of this Rb compound.

So if CsZr2(PO4)3 fits the bill with regards to stoichiometry, insolubility and beam stability, I would be very interested.   

Or is there a Cs compound that is even higher Cs concentration?  We were originally hoping for a CsZrOPO4 compound, but when Marc tried to synthesize it we got CsZr2(PO4)3 instead, so maybe that's the only choice in a Cs phosphate?
john
« Last Edit: January 26, 2018, 12:41:55 PM by Probeman »
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Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #8 on: January 26, 2018, 12:43:05 PM »
So if CsZr2(PO4)3 fits the bill with regards to stoichiometry, insolubility and beam stability, I would be very interested.   

I wonder if we could "crowd source" this project?  What would you guess it would cost for you to make say 5 or 10 grams of this compound?
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crystalgrower

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #9 on: January 26, 2018, 05:01:36 PM »
The Cs4Sr(PO3)6 calculates about 46% Cs.

It's straightforward to make in a Pt crucible.  You need Cs2CO3 and SrO or SrCO3 and H3PO4 and a furnace that will hold at  400C.  It takes a few hours to react the mixture on a hotplate to a stable liquid.   Then you let it cook overnight at 400C.

Time depends on crucible size.  Only caveat is that you must have pure Pt.   The alloy used for XRF pellets will not survive for long with the P2O5 glass that is formed. 


Brian Joy

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #10 on: January 27, 2018, 10:53:09 AM »
I'd definitely be willing to contribute to an effort to synthesize Cs4Sr(PO3)6, as I've been looking for a reliable Cs standard for a number of years.  I get 48.6 wt% Cs and 51.6 wt% Cs2O.
Brian Joy
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Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #11 on: January 27, 2018, 04:38:58 PM »
It's straightforward to make in a Pt crucible.  You need Cs2CO3 and SrO or SrCO3 and H3PO4 and a furnace that will hold at  400C.  It takes a few hours to react the mixture on a hotplate to a stable liquid.   Then you let it cook overnight at 400C.

Time depends on crucible size.  Only caveat is that you must have pure Pt.   The alloy used for XRF pellets will not survive for long with the P2O5 glass that is formed.

I would contribute something as well for a Cs synthetic if you think Cs4Sr(PO3)6 would be stoichiometric.  Do you know if it is stable under the beam and non water-soluble?
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crystalgrower

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #12 on: January 29, 2018, 01:29:27 PM »
Right now I will say this

1. The Cs4Sr(PO3)6 is stoichiometric and not water soluble. Other oligophosphates I made are beam stable single crystals.

2.  Those of you who bought REEP5O14 standards between September 2009 and December 2011 were buying my work.  Of course the products only bore the company name. 

3. I have sufficient feedback here to try a batch when the weather improves in March or April (garage operation). Batch size would be 5 grams or so.

4. I'm in Toronto so I will contact Brian Joy off line to discuss assistance.  I have the raw materials. 


crystalgrower

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #13 on: January 29, 2018, 01:59:24 PM »
Thorium: The Taylor collection had large quantities (~300 grams) of ThO2 that had been cut into 2mm cubes.  These appear to all have ended up in the subset purchased by Astimex.  The material has been used longterm for probe, it is sintered from grains and takes a good polish.  The 2mm x 2mm face shows as about 8 grains after polishing. 

Maybe somebody can invite them to see if they want to sell groups of 5 cubes for a special price?  5 cubes would be close to a gram.   The advantage is that synthesis of any other phase would require very costly waste disposal. 

And how do people feel about simple compounds?  Oxides vs fluorides vs sulfies vs silicates?

Probeman

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Re: Standards Which Should Be Developed For EPMA Next
« Reply #14 on: July 24, 2018, 01:56:39 PM »
Here's a variation on a crazy idea from Donovan...

As we know, trace element accuracy is possible in EPMA but there are a number of artifacts that can make such analyses problematic. Depending on the specific matrix involved there may be issues with off-peak background positions, on-peak interferences, sample (and detector) absorption edges and beam sample sensitivity to name just a few.

Therefore many of us are seeking secondary standards for checking our trace element accuracy in EPMA.  The problem of course is that getting homogeneous (and accurate) trace element standards is difficult.  For both natural and synthetic materials we have problems with inclusions or contamination and heterogeneity. Then there are the issues with knowing what the trace element level actually is.  Is it 110 PPM or is it 115 or 105 PPM?  Who knows?  Every technique has its systematic errors.  This is discussed in some length in this topic here:

http://probesoftware.com/smf/index.php?topic=928.0

But there are two values that we can know with very high accuracy, First we can know something is 100% with extremely high accuracy.  For example, if our Si or SiO2 EPMA standard has been analyzed for possible contaminants and all are less than a few PPM, then we can be pretty confident that our Si is 99.99% Si or our SiO2 is 99.99% SiO2 (or however many 9s we checked for).

Likewise, we can also know that something is *zero* with extremely high levels of accuracy.  In fact in these cases we can have trace element accuracy *equal* to our measurement precision level, by simply using a matrix matched pure synthetic blank standard.

For example, if we use highly sensitive techniques such as ICP-MS on a pure synthetic standard material, and we know that our possible contaminants (that is, trace elements of interest) are well below the detection limit of the microprobe (let's say 1 PPM), then by measuring a pure synthetic standard which is similar to our matrix and carefully analyzed so we know the traces are below EPMA sensitivity, we can now check the accuracy of our EPMA trace element measurement by simply seeing if we can measure zero. If we do not obtain a zero measurement, then something is wrong, perhaps the background is curved (it always is!). Or there's a spectral interference, etc., etc.  This of course is where the blank correction in PFE can be applied to correct our unknowns.

For very simple unknowns such as measuring traces in say quartz, we are already fine, because there are many highly pure SiO2 materials available at low cost.  But that is not the case for other materials of interest.

Let's take a simple case of measuring traces in say olivine.  We'd like to have matrix similar to our unknown. But growing a homogeneous olivine of intermediate composition is difficult. There's always some zoning in an MgFeSiO4 composition, but wait! We don't care what the major element composition is, we only care about the trace elements in some olivine composition.  That is we really only care that the trace elements Mn, Ni, Cr, Al, Ca, etc. are below the detection limit for EPMA.  That way we can check our trace element accuracy in a matrix matched standard because we know regardless of the actual Fe-Mg ratio, we should obtain zero +/- the measurement precision.

In fact, we would actually *want* our olivine trace element standard to have a range of composition!  Why? Because then we can find an appropriate Mg rich or Fe rich (matrix matched) area of our synthetic olivine to test our zero measurement accuracy!

Now let's take a nasty case of trace U and Pb in monazite. Traditionally we would try and obtain a perfect homogeneous synthetic monazite that is accurately doped with the trace elements of interest.  But that is extremely difficult to synthesize.  It is usually highly zoned in major element composition (and trace elements) and therefore it can not really be considered a standard.

But, as long as the trace elements in question (say U and Pb), are *not* present at EPMA detection limits- it does not matter!  Again, by having a highly zoned synthetic monazite that we know is free from U and Pb, we have the perfect standard to check our trace element accuracy and we can probably find an intermediate composition of Ce, Nd, Gd, Sm, Th, etc. phosphate, that is a close matrix match to our actual unknown and we have high accuracy for zero concentrations of U and Pb.

We can continue the same line of thinking to traces in alloys, traces in sulfides, etc.  Again: the actual composition doesn't have to be an exact match (or even known accurately for that matter). What really matters is that the trace elements of interest are below EPMA detection limits in a similar matrix.

So what I think we really need are highly purified starting materials, and then synthesize some olivines, monazite, etc. for use as secondary trace element standards, to test our trace accuracy determinations in a close matrix match material.

As has been said before:  "if you can't measure something, try measuring nothing, because if you can't measure nothing, you can't measure anything".  And I would take it one step further: " for best accuracy, try measuring nothing, in a matrix matched pure synthetic material".

Hey I told you it was crazy!   :)     What do you think?
« Last Edit: July 24, 2018, 01:59:10 PM by Probeman »
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