Poll
Question:
What would your lab be willing to pay to obtain a reasonable (~gram) quantity of a single crystal standard material?
Option 1: Not Interested
Option 2: $25
Option 3: $50
Option 4: $100
Option 5: $200
This topic is for the development of new standard materials.
At the recent Cameca user's meeting (which included a few JEOL users as well!), we discussed some ideas regarding standards. Anette Von der Handt suggested that we start to organize the community to create a priority list of new standard materials that should be developed. Suggestions for new materials should be made to this topic.
The idea would be to organize an effort to prioritize the development of a kilogram or so of material sufficient for distribution to every probe lab globally.
To start things off I can suggest two standard materials which I deem important and suitable for development. Specifically a Rb and a Cs standard. In fact I had worked with a chemistry grad student a number of years ago at Berkeley to develop an excellent Rb standard, but we only produced a gram or so of the material which is RbTiOPO4. But what a material!
The crystals were beautiful water clear and double terminated. RbTiOPO4 is also insoluble in water and completely robust under electron bombardment. It is also perfectly homogeneous and apparently homogeneous in Ti and P. Based on my own use of this material I think this could be the perfect standard for Rb.
Unfortunately there is no Cs analog, so more research and discussion is necessary.
Have you considered glass standards for these elements?
Quote from: BenH on March 09, 2015, 09:15:30 AM
Have you considered glass standards for these elements?
Hi Ben,
Yes, you be the "glassman", since that is your "bread and butter" as they say...
My only issue with glass standards (and don't get me wrong- I love some, e.g., the NIST mineral glasses), but although we can have purity constraints on synthetic glasses, we cannot get a handle on stochiometry. Since I mentioned the NIST glass, I will point out that the NIST analyses are in error to the extent that some of the Fe is Fe2O3, not FeO. See here:
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 1.5026 1.0818 1.4678 1.2046 2.5078 1.9914
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: 1.2578 1.1793 1.5587 1.0770 1.4589 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
So, once we make the glass, then our problems really begin. What did we make? This is not an inexpensive question to answer.
With a synthetic single crystal of say Al2SiO5 or RbTiOPO4 there is no doubt what we made accuracy wise based on purity and an x-ray diffraction pattern.
Are the conditions and method of synthesis of the K-series CMASFe glasses available?
For Fe-bearing glasses the speciation of Fe will always be a problem. Accessing oxygen fugacities where Fe is 100% Fe2+ or 100% Fe3+ is difficult to intractable for large scale synthesis (for compositions that are somewhat like natural magmas anyway). For 100% Fe3+ oxygen pressures greater than 1 bar are necessary, and 100% Fe2+ cannot be produced by equilibration with pure CO gas (in addition to the problem of graphite precipitation).
At ANU we are in the process of small scale synthesis of some S-bearing CMAS glasses with controlled S-speciation (100% S2- and 100% S6+ compositions) for redistribution as a standard. I will have more details when the synthesis is complete and I am ready to send them out.
Hi John.
I get your point about the advantages to stoichiometry. In the case of elements in common rock forming materials, I think minerals are very preferable to glasses. You pointed out the need for a Rb standard and proposed a reasonable mineral. If you are measuring something very different in composition, you rely heavily on ZAF. In many cases this works quite nicely. In many cases the matrix corrections result in small inaccuracy. There is no perfect standard. The trade off thus becomes using a standard that is more like the unknown versus a confidently constrained crystalline standard that is very different than your unknown. Which results in more uncertainty? That is an issue I commonly face measuring the materials I face. Any input to this dilemma would be appreciated.
Thanks John.
Quote from: BenH on March 14, 2015, 09:20:50 AM
I get your point about the advantages to stoichiometry. In the case of elements in common rock forming materials, I think minerals are very preferable to glasses. You pointed out the need for a Rb standard and proposed a reasonable mineral. If you are measuring something very different in composition, you rely heavily on ZAF. In many cases this works quite nicely. In many cases the matrix corrections result in small inaccuracy. There is no perfect standard. The trade off thus becomes using a standard that is more like the unknown versus a confidently constrained crystalline standard that is very different than your unknown. Which results in more uncertainty? That is an issue I commonly face measuring the materials I face. Any input to this dilemma would be appreciated.
Hi Ben,
Yes, that is exactly the dilemma.
That is: is the accuracy of the std composition or the accuracy of the physics the dominating factor? And I would agree with you that the answer sometimes is "it depends". Though for trace and minor elements, I would argue that precision is more often the culprit than std accuracy or physics... but that's another story.
But if we assume that we can obtain stoichiometric oxides, silicates and other minerals, then these materials are more than adequate for many compositions we generally face, especially when armed with the current physics. Which the accuracy of, I will contend, has improved immensely in the last decade based on my understanding of the literature.
Now, there are still going to be chemical state issues for some materials, especially for low energy lines, and to be sure, there are also a few "black holes" in the periodic table (e.g., Si ka in hafnium) where an emission line is just above the critical excitation energy of an absorber edge in addition to large atomic number effects, but in general I think it makes sense to try and eliminate inaccuracy in many of our standards and more importantly, make these materials available in large quantities to all labs world wide, so we are all at least "on the same page" so to speak.
I am discussing how we might synthesize some of these standard materials with Marc Schrier who now works/operates
http://www.calchemist.com/
growing crystals of all sorts.
He was the original student at UC Berkeley that synthesized the RbTiOPO4 material discussed above (that some of you have) for my UCB EPMA lab years ago when he was a chemistry student there and I was learning what an EPMA was.
We decided to maybe start with making a much larger amount of RbTiOPO4 and so he started strategizing and asked first if there was any trace Pt in the material since he used a Pt crucible... other crucible materials might be possible also (and cheaper).
I analyzed the RbTiOPO4 material last night for Pt and at 15 keV I got:
0.029 wt% +/- 0.030
at 20 keV I got:
0.007 wt% +/- 0.013
So below detection limit. This was using the Pt La line at 100 nA.
Turns out the Pt Ma line is interfered with by the Rb LG3 line!
I will keep you all informed as to progress. In the meantime I would like to ask, if we try to "crowd source" this material so we can create enough material for every EPMA (and SEM?) lab in the world (~1 Kg?), how much money would each lab be able to "cough up" to accomplish this?
I have attached a poll to this topic... see the top of this page
On an slightly related topic please check this post also:
http://smf.probesoftware.com/index.php?topic=449.msg2479#msg2479
The orthorhombic form of CsTiOAsO4 might be a possible material to produce as a Cs standard.
According to Loiacono et al. (1993. Journal of Crystal Growth 131, 323-330) it can be grown by methods similar to KTiOPO4; they report 30 mm as the largest dimension.
In a couple of papers, Cheng et al. (1993. Journal of Crystal Growth 132, 280-288 and 289-296) suggest self-fluxing growth is best, and crystals up to 30-32 mm.
Quote from: AndrewLocock on March 25, 2015, 10:58:09 AM
The orthorhombic form of CsTiOAsO4 might be a possible material to produce as a Cs standard.
According to Loiacono et al. (1993. Journal of Crystal Growth 131, 323-330) it can be grown by methods similar to KTiOPO4; they report 30 mm as the largest dimension.
In a couple of papers, Cheng et al. (1993. Journal of Crystal Growth 132, 280-288 and 289-296) suggest self-fluxing growth is best, and crystals up to 30-32 mm.
Hi Andrew,
Apparently great minds think alike, because Marc Schrier wrote to me by email last week and also suggested the arsenate! Here are some of his comments:
Quote
CsTiOAsO4, 39.6% Cs by weight
CsZrOPO4, 39.7% Cs by weight
for comparison sake, the RbTiOPO4 is 29.7% Rb by weight.
I assume you prefer a high weight %, but these are nearly the same. Do these sound of interest? Do you have any preference between the two? Apparently they are both water insoluble. The phosphate is probably an easier synthesis, but I suspect the two will be similar to the RbTiOPO4 preparation.
We'd probably prefer the phosphate just because arsenic is no fun to play with!
john
Talking with Marc Schrier just now and he might have found a source for quantities of RbTiOPO4 for us, but I'm checking into pricing...
In the meantime I think we should start making a "wishlist" of ideal materials for various elements. My thinking is that for some elements identifying materials that are relatively beam stable and *not* water soluble can be daunting. But there are some "bad boys" of the periodic table in my experience:
The halogens: F, Cl, Br and I
The alkalies: especially Rb, Cs but also an oxygen free Na standard would be ideal to be utilized as an interference for Na on oxygen.
Also semi-metals such as In, Sn, P etc.
What standards are you interested in obtaining?
Hi Guys,
Just before making contact with a RbTiOPO4 (RTP) optics supplier (that John's going to chat with further), I started a ~1 week long flux prep with the ~17 year old flux I used to grow the RTP crystals John has been working with. I got a great yield (486.4 mg) (at this scale), but the crystals are clear and yellow/gold instead of clear and colorless (see attached picture if I got it to work). I have a feeling the flux is now depleted in P2O5, and the excess Rb2O is dissolving the platinum crucible (there was a 3.3 mg loss). There is also a chance the crucible had some trace contamination from the last thing I ran in it or that this TiO2 is not pure enough. For now I think we should just wait and see how John's discussion goes, but if it does not go well (prohibitively expensive, etc.), here's what John and I were planning: Unfortunately the current synthesis is in a ~10 cc platinum crucible, and scaled up a little would only give about 2 g RTP per week. Unfortunately a giant platinum crucible would be prohibitively expensive, so that's a lot of runs to prepare John's goal of 1 kg! -Maybe the community can convince John to bringing that amount down. Our plan was to prepare some RTP from the platinum crucible as a baseline, and then try some alternative (and cheaper) crucibles like alumina, zirconia, silver, and quartz. And then maybe even nickel and graphite in an inert atmosphere if needed. If any work (and John does not see any contamination in the microprobe), then they could be scaled up for a much larger batch.
For now I'll dabble with growing a cesium standard, but if anyone has a material they need prepared and wants to chat about it, drop me a line. I've got gear to run molten salt fluxes and hydrothermal syntheses that should be adequate for most crystals.
Edit by John: The guy at Coherent is out for a week and he's apparently the one I need to talk to. Yes, please send me a crystal to check for Pt. FYI: 1 kg is an upper limit!
Just spoke with a guy at Coherent and he thinks they have scraps of pure single crystal RbTiOPO4 that they can make available for us. The only possible contaminant is K which is intrinsic to the RbCO3 starting material.
Will let you all know how this pans out...
Quote from: Probeman on April 13, 2015, 11:02:45 AM
Just spoke with a guy at Coherent and he thinks they have scraps of pure single crystal RbTiOPO4 that they can make available for us. The only possible contaminant is K which is intrinsic to the RbCO3 starting material.
Will let you all know how this pans out...
It's in the mail.
As soon as I check it for purity and run an XRD I'll make it available for a nominal fee, to cover shipping and handling and a little more so we can start to build up a "kitty" of money for developing further synthetic materials in large quantities. I want to make this material available to to everyone in say, gram quantities, which should last most labs a lifetime or more, I'm thinking... what do you all think?
The poll above has $100 as the most popular "crowd source" amount, so maybe we'll start with a gram of RbTiOPO4 for $100 to start with and see if that is popular enough...
Marc Schrier is thinking that the CsZrOPO4 might be a good material to try and synthesize next?
I'd certainly be interested in a good Cs standard. Currently I use a natural pollucite from Hebron, Maine that I've characterized by a combination of microprobe analysis, stoichiometry, and solution ICP-MS (particularly to get Li2O). My characterization of it is not really as satisfactory as I'd like it to be, especially since I've had to apply a number of assumptions, namely nAl + nSi =3, n large cations = nAl, and nCs + nH2O = 1. I also have some Cs2SiF6 for which I paid an arm and a leg to get from SPI; however it turns out to be too water-soluble for water-based polishing (learned this the hard way) and is quite beam-sensitive. The only other one I have is Corning Glass 95-IRW, which only contains 0.7 wt% Cs2O.
What have other people been using as a Cs standard?
In looking over what starting materials I have here, I don't have any good cesium starting materials. Before I purchase some, I figured I'd bounce it off the group in case someone has some to share (or maybe access to a reuse facility). To start, the materials do not need to be particularly pure, and only once everything is working well (prepare crystals (PXRD), it's water insoluble, polishes nicely, holds up to the beam, looks homogeneous...), then I can pick up purer starting materials. To prepare the flux(es), any of the following would work as a cesium source: Cs, Cs2O, CsOH, CsOH•H2O, Cs2CO3, CsHCO3, CsOAc (CH3COOCs, cesium acetate), HCOOCs (cesium formate), Cs3PO4, Cs2HPO4, or CsH2PO4. If you have any you can share, let me know, otherwise I'll try to place an order for some starting materials soon. I'm not sure if CsZrOPO4 will work, but at least Cs2Zr(PO4)2 and CsZr2(PO4)3 have been prepared. There are also some Cs/Ti/P/O's. I probably ought to do some literature searches too and see what I can dig up!
Quote from: marcschrier on April 22, 2015, 07:24:20 PM
In looking over what starting materials I have here, I don't have any good cesium starting materials. Before I purchase some, I figured I'd bounce it off the group in case someone has some to share (or maybe access to a reuse facility). To start, the materials do not need to be particularly pure, and only once everything is working well (prepare crystals (PXRD), it's water insoluble, polishes nicely, holds up to the beam, looks homogeneous...), then I can pick up purer starting materials. To prepare the flux(es), any of the following would work as a cesium source: Cs, Cs2O, CsOH, CsOH•H2O, Cs2CO3, CsHCO3, CsOAc (CH3COOCs, cesium acetate), HCOOCs (cesium formate), Cs3PO4, Cs2HPO4, or CsH2PO4. If you have any you can share, let me know, otherwise I'll try to place an order for some starting materials soon. I'm not sure if CsZrOPO4 will work, but at least Cs2Zr(PO4)2 and CsZr2(PO4)3 have been prepared. There are also some Cs/Ti/P/O's. I probably ought to do some literature searches too and see what I can dig up!
Hi Marc,
I have 20-25 g Cs2CO3 with stated purity = 99.5 wt%. Would this be enough for you to get started? If so, I'd be glad to send it.
Brian
Quote from: marcschrier on April 22, 2015, 07:24:20 PM
In looking over what starting materials I have here, I don't have any good cesium starting materials. Before I purchase some, I figured I'd bounce it off the group in case someone has some to share (or maybe access to a reuse facility). To start, the materials do not need to be particularly pure, and only once everything is working well (prepare crystals (PXRD), it's water insoluble, polishes nicely, holds up to the beam, looks homogeneous...), then I can pick up purer starting materials. To prepare the flux(es), any of the following would work as a cesium source: Cs, Cs2O, CsOH, CsOH•H2O, Cs2CO3, CsHCO3, CsOAc (CH3COOCs, cesium acetate), HCOOCs (cesium formate), Cs3PO4, Cs2HPO4, or CsH2PO4. If you have any you can share, let me know, otherwise I'll try to place an order for some starting materials soon. I'm not sure if CsZrOPO4 will work, but at least Cs2Zr(PO4)2 and CsZr2(PO4)3 have been prepared. There are also some Cs/Ti/P/O's. I probably ought to do some literature searches too and see what I can dig up!
Hi Marc,
How much Cs starting material would you need to make a few test runs? How much would that cost?
I haven't received any RbTiOPO4 from the guy at Coherent yet. I'll ping him Monday.
john
Brian,
That would be great if you could send it down! Twenty grams Cs2CO3 should be enough to get me started; I have the other chemicals. My address is Marc Schrier, Calchemist, 871 Industrial Rd. Suite K, San Carlos, CA 94070, USA.
John,
For the first phase I figured I'd get some cheap Cs source to figure out what I can make, and if it stands up. The cheapest Cs source I came across was Cs2CO3, 99%, and it was just $0.50/g Cs, so ~$100 for 250 grams. Brian's Cs2CO3 should get me going, and if it goes well, then I'll be more focussed on purity for the next purchase, and we can discuss those requirements when we get to that stage.
In other news I contacted Tom Chatham with Chatham Gems to see if they could offer any assistance, but all of their synthetic gems are doped.
-Marc
I got some RbTiOPO4 material from Coherent. I'm having Julie save a piece for us to analyze for traces and the rest I'll send to Mark Schrier for distribution. I believe he will charge around $100/gram for this material, with most of the proceeds going towards buying raw material for our next community standard project.
I'm thinking CsZrOPO4...
I finally got around to measuring some trace elements in the RbTiOPO4 material. I measured K, Cs, Na, Ca and Mg using 20 keV, 100 nA counting for 400 seconds on-peak and 400 seconds off-peak:
Un 7 RbTiOPO4
TakeOff = 40.0 KiloVolt = 20.0 Beam Current = 100. Beam Size = 5
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 1000, Magnification (imaging) = 1000)
Image Shift (X,Y): .00, .00
Number of Data Lines: 7 Number of 'Good' Data Lines: 7
First/Last Date-Time: 06/11/2015 09:37:16 AM to 06/11/2015 01:14:15 PM
WARNING- Using Exponential Off-Peak correction for cs la
WARNING- Using Exponential Off-Peak correction for na ka
Average Total Oxygen: .000 Average Total Weight%: 100.015
Average Calculated Oxygen: .000 Average Atomic Number: 21.781
Average Excess Oxygen: .000 Average Atomic Weight: 30.549
Average ZAF Iteration: 2.00 Average Quant Iterate: 2.00
Un 7 RbTiOPO4, Results in Elemental Weight Percents
ELEM: K Cs Na Ca Mg Rb Ti P O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC SPEC SPEC
BGDS: LIN EXP EXP LIN LIN
TIME: 400.00 400.00 400.00 400.00 400.00 --- --- --- ---
BEAM: 100.94 100.94 100.94 100.94 100.94 --- --- --- ---
ELEM: K Cs Na Ca Mg Rb Ti P O SUM
360 .015 .013 -.014 .000 -.001 34.979 19.604 12.676 32.741 100.014
361 .016 .012 -.016 .000 -.001 34.979 19.604 12.676 32.741 100.012
362 .016 .015 -.012 .000 .000 34.979 19.604 12.676 32.741 100.019
363 .015 .013 -.017 .000 -.002 34.979 19.604 12.676 32.741 100.010
364 .016 .015 -.010 .000 .000 34.979 19.604 12.676 32.741 100.021
365 .015 .013 -.012 .000 .000 34.979 19.604 12.676 32.741 100.017
366 .016 .012 -.013 .000 -.001 34.979 19.604 12.676 32.741 100.014
AVER: .016 .014 -.013 .000 -.001 34.979 19.604 12.676 32.741 100.015
SDEV: .000 .001 .003 .000 .001 .000 .000 .000 .000 .004
SERR: .000 .000 .001 .000 .000 .000 .000 .000 .000
%RSD: 2.86 9.44 -18.91 273.41 -74.31 .00 .00 .00 .00
STDS: 374 1125 336 358 358 --- --- --- ---
STKF: .1102 .2652 .0583 .1676 .0644 --- --- --- ---
STCT: 8027.8 14411.6 630.3 6846.5 3948.1 --- --- --- ---
UNKF: .0001 .0001 .0000 .0000 .0000 --- --- --- ---
UNCT: 9.9 6.3 -.5 .1 -.2 --- --- --- ---
UNBG: 44.7 162.4 7.8 37.9 23.0 --- --- --- ---
ZCOR: 1.1549 1.1603 2.6938 1.0538 1.8504 --- --- --- ---
KRAW: .0012 .0004 -.0009 .0000 -.0001 --- --- --- ---
PKBG: 1.22 1.04 .93 1.00 .99 --- --- --- ---
Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):
ELEM: K Cs Na Ca Mg
360 .001 .002 .006 .001 .001
361 .001 .002 .006 .001 .001
362 .001 .002 .006 .001 .001
363 .001 .002 .006 .001 .001
364 .001 .002 .006 .001 .001
365 .001 .002 .006 .001 .001
366 .001 .002 .006 .001 .001
AVER: .001 .002 .006 .001 .001
SDEV: .000 .000 .000 .000 .000
SERR: .000 .000 .000 .000 .000
Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):
ELEM: K Cs Na Ca Mg
60ci .000 .000 .001 .000 .000
80ci .000 .001 .001 .000 .000
90ci .000 .001 .002 .000 .000
95ci .000 .001 .002 .001 .000
99ci .000 .002 .004 .001 .001
The only problematic element was Na due to a very congested background as seen here:
(https://smf.probesoftware.com/oldpics/i58.tinypic.com/k3op50.jpg)
I'll need more work to improve the Na background measurement. But in the meantime this looks like excellent material with less than 200 PPM of K and Cs and no Ca or Mg.
john
Quote from: Probeman on June 11, 2015, 03:05:44 PM
I'll need more work to improve the Na background measurement. But in the meantime this looks like excellent material with less than 200 PPM of K and Cs and no Ca or Mg.
john
Nice! Thanks for your work on this. Is the material available from Marc at this point?
Hi everyone,
Yes, I have the material, and it's ready for distribution at $100 for a 1 g sample. For more details see http://www.calchemist.com/standards.htm
I'm working on CsZrOPO4, CsTiOPO4, and CsTiOAsO4, and Ca5(PO4)3Cl, so those are the next things to hopefully see!
-Marc
G'day
Very interesting and important topic!
I guess in an ideal world, every lab would use the same standards. That would make the output from different labs better comparable. The standards would be large homogeneous grains with high concentrations of the element of interest and of course beam stable.
At the moment, everybody has access to the Smithsonian's, which are available free of charge(?). The problem that I see with these standards is, that most standards are "small" grains. Some are not homogeneous or have inclusions and they are all natural, not synthetic. Larger grains are available to purchase at places like Astimex, P&H, ...
I like the idea of synthesizing standards. It is a good feeling to know the composition of the standard that you are using for calibration to measure an unknown. We have quite a few standards where I am not sure how well we actually know their composition....
Ok, back to the ideal world... (@Marc, I will try to convince John) I am not sure, if we need 1kg of material. First of all, most labs are basically broke, because every University wants to do good research, but haven't figured out yet that they need good equipment for that as well (therefore, not every lab will buy all available standards). Second, a lot of labs don't analyses the whole periodic table, but only what the University is "specialized" in. Third, ...
Back to the actual topic, here in Hobart, we do analyse the whole periodic table except for Cs and Rb. ;)
I guess a standard that we could use is something with Fluorine (ideally large, homogeneous, beam stable, ...). We used to use a Topaz, but we have to replace it and haven't really found a good standard yet. You could use an Apatite or Mica's but they are not beam stable at all. So, to cut a long story short, we are very interested in a Fluorine standard.
Cheers
Sandrin
Quote from: Sandrin Feig on June 21, 2015, 11:08:28 PM
I guess in an ideal world, every lab would use the same standards. That would make the output from different labs better comparable. The standards would be large homogeneous grains with high concentrations of the element of interest and of course beam stable.
Yes, exactly. If we make enough of a standard material, and every lab can obtain that ideal standard for $100 a gram, then maybe every lab in the world *can* use the same standard, at least in these particular places on the periodic table, e.g., Rb.
Quote from: Sandrin Feig on June 21, 2015, 11:08:28 PM
At the moment, everybody has access to the Smithsonian's, which are available free of charge(?). The problem that I see with these standards is, that most standards are "small" grains. Some are not homogeneous or have inclusions and they are all natural, not synthetic. Larger grains are available to purchase at places like Astimex, P&H, ...
Yes, free fly specks! Our proposal is to instead create enough of a desired synthetic material that is homogeneous, stable and free from inclusions and available for a nominal amount- $100 won't break the bank for anyone! The money Marc will make on these sales will go towards synthesizing the next "crowd sourced" standard.
Quote from: Sandrin Feig on June 21, 2015, 11:08:28 PM
Ok, back to the ideal world... (@Marc, I will try to convince John) I am not sure, if we need 1kg of material. First of all, most labs are basically broke, because every University wants to do good research, but haven't figured out yet that they need good equipment for that as well (therefore, not every lab will buy all available standards). Second, a lot of labs don't analyses the whole periodic table, but only what the University is "specialized" in. Third, ...
1 kg sounds like a lot but it is an upper limit is the point. It depends on the amount we want to distribute and how may labs are there. Here's our thinking: if we have a few hundred grams of material at least, we we'll be able to offer *everyone* 1 gram splits of the material so you won't have to do with a few fly specs anymore! 1 gm of material should last any lab forever! And how many labs are there? Well let's assume a few hundred EPMA labs, so that's a few hundred grams already.
But what about SEM labs? Shouldn't SEM labs also have standards?
http://smf.probesoftware.com/index.php?topic=302.msg1530#msg1530
Adding in SEM labs means we would need 500 or more grams to supply every lab in the world...
Yes, we are starting with Rb and Cs because we already know they are difficult to find good standards for. Let get more suggestions- this is a crowd sourced effort!
I should also mention, these are not intended to be secondary standards that are similar to your unknown matrix. These are intended to be primary standards, which for statistical purposes (see your quant expressions) need to provide the highest x-ray intensity for a given concentration. Usually that means a major amount of the element of interest regardless of matrix. The ideal standard for this? Yes, a pure metal- 99.999% pure of course!
But of course that doesn't work for certain elements, such as Rb and Cs! Hence our synthesis and distribution efforts...
Quote from: Sandrin Feig on June 21, 2015, 11:08:28 PM
Back to the actual topic, here in Hobart, we do analyse the whole periodic table except for Cs and Rb. ;)
I guess a standard that we could use is something with Fluorine (ideally large, homogeneous, beam stable, ...). We used to use a Topaz, but we have to replace it and haven't really found a good standard yet. You could use an Apatite or Mica's but they are not beam stable at all. So, to cut a long story short, we are very interested in a Fluorine standard.
I have to wonder if some labs have avoided Rb and Cs simply because they didn't have decent primary standards...? ???
But, no worries, maybe no one you know is interested in Rb and Cs. We do want to hear what your lab needs. You say, you are interested in fluorine, and that you "used to have" a topaz standard... what happened to it? Did it wander off? Disappear during polishing?
I agree that the apatites and phlogopite are beam sensitive. Tell us, was the topaz beam stable? Was it natural or synthetic? Did it have any OH?
Marc has said that topaz would be easy to grow, but what about the OH molecule?
Quote from: Owen Neill on June 25, 2015, 09:21:06 AM
One of my users suggested synthetic olivine-group (X2SiO4, X = Mg, Cr, Mn, Fe, Co, Ni) minerals as potential synthetic standards, especially for transition metals like Co and Ni for which there don't seem to be a lot of options.
I believe some of these may already be in production - our lab inherited a synthetic forsterite which I use fairly often, and I've heard of synthetic fayalite, tephrite and Co-olivine floating around (possibly ORNL products?), but I don't know of any consistent source for them.
Hi Owen,
Funny, but I recently contacted Lynn Boatner (Oak Ridge Nat'l Lab) regarding any Fe2SiO4 material he might have left over or at least a recipe for making it for Marc Schrier. I have some of his original synthetic fayalite and it was wonderful- full end member and no metallic Fe. Unfortunately he has not responded.
So, yes this would be an excellent candidate for synthesis for our crowd sourcing efforts... any one have any recipes for making synthetic fayalite?
I should also ask what you want the Co, Mn, Ni, etc olivines for... I have some transition metal olivines from the Purdue crystal lab many moons ago, but the only real use I've found for them is testing matrix corrections and MAN corrections.
That is to say, for trace element work, you can utilize the pure metal or oxide just as well.
Quote from: Owen Neill on June 29, 2015, 10:26:18 AM
Quote from: John Donovan on June 26, 2015, 06:32:46 PM
I should also ask what you want the Co, Mn, Ni, etc olivines for... I have some transition metal olivines from the Purdue crystal lab many moons ago, but the only real use I've found for them is testing matrix corrections and MAN corrections.
1. Some of the glasses/compounds/synthetic minerals/stuff from our Materials Science folks can have a fair amount of Co, Mn, Ni, etc (1-10 wt% level, more on occasion).
Hi Owen,
Thanks for the feedback.
Please believe me, I'm not trying to discourage the development of synthetic crystal standards, but I am trying to keep us focused on new standards that will have the most positive impact on our analyses. If your silicate samples have 10% Co, Mn, Ni, etc. then you might have a case for us synthesizing some unusual end-members of the olivine family.
But because the Co, Mn, Ni, etc. emission lines are quite energetic, and these materials all have about the same average atomic number, it's not clear to me that having these end-member standards available, will provide an significant improvement. Now the situation is quite different for measurements of Si Ka in these materials, because the absorption correction is quite large and even worse is the situation for high atomic number silicates when the atomic number correction starts to really kick in and one is using SiO2 as a Si standard!
One of the most useful crystals which I was lucky enough to obtain some perfect natural crystals of was alamoite or PbSiO3. This is the perfect Pb standard for the microprobe. HfSiO4 would also be interesting but there is a nasty absorption edge problem for Si ka, which incidently does make it an excellent material for physics studies...
http://smf.probesoftware.com/index.php?topic=152.msg1637#msg1637
Quote from: Owen Neill on June 29, 2015, 10:26:18 AM
2. A lot of the sulfides we get can have major Ni and Co (again, > or >>1wt% levels).
While the synthetic olivines wouldn't be the best matrix match (especially for the sulfides) they would at least polish well and not degrade as badly over time as the Co and Ni pure metals/sulfides I use now, as well as having better and more reproducible "published" compositions.
Similar for these minor concentrations as above. For now you're better off with polishing your standard mount once a year. But I think it is a good idea to get to these weird olivine materials at some point.
Quote from: Owen Neill on June 29, 2015, 10:26:18 AM
As far as recipies go, the only one I've seen is a sol-gel method for growing nanocrystalline fayalite. Obviously we don't want nanocrystalline material, so this may not be the most useful, but the reference is:
DeAngelis, M.T., Rondinone, A.J., Pawel, M.D., Labotka, T.C. and Anovitz, L.M. (2012) Sol-gel synthesis of nanocrystalline fayalite (Fe2SiO4). American Mineralogist, v. 97, p. 653-656, doi:10.2138/am.2012.3899
Marc may find this helpful, thanks!
Quote from: Owen Neill on June 29, 2015, 05:40:07 PM
Fair enough - if I'm the only one after these, then let's bump this down the priority list. And if you have some leftovers of the Purdue olivines and want rid of them, I'd be open to negotiation...
Eventually we want to be able to grow them all!
But if you have some dollars laying around the lab I'm sure Marc Schrier would be open to doing some custom crystal growth for you! And then we'll "borrow" material from you!
john
Do you guys (with academic ties and a lot more experience with government funding) think this is the sort of thing we could get NSF, NIST, etc. to fund as a research project? -Marc
If CsZrOPO4 doesn't work then you could try CsAlTiO4. Gatehouse (Acta Crystallographica) reported making it from "CsNO3 ('optical grade'), TiO2 (Hopkins & Williams) and A1203 (BDH) were heated initially for 24 h at 1200 K followed by 48 h at 1400 K then slow cooled at 10 K min-~ in an open platinum crucible. An allowance was made for the loss of caesium at the reaction temperature" - this allowance is +10% relative for the method specified. Don't know what its solublity is like.
Last fall, I looked around for sources of some various oxides and simple compounds, and I found that American Elements stocks a number of potentially interesting materials. Their minimum quantities typically run $500-$600 (according to Riley Peck riley.peck@americanelements.com ) and are much more than any individual probe or SEM lab would need. Purchasing some for redistribution could work, though. Has anyone explored their catalog?
We probed the first trial of the Cs Zr phosphate on the weekend and it appears to have a different stoichiometry than anticipated.
wt%:
ELEM: Cs Zr P Hf Rb Si O SUM
116 20.9 30.1 16.1 .44 n.d. .000 32.688 100.2
117 20.8 29.5 15.9 .50 n.d. .000 32.211 98.9
118 20.9 29.8 16.2 .48 n.d. .000 32.784 100.2
119 20.8 30.5 15.7 .45 n.d. .000 32.352 99.8
120 20.9 30.2 16.0 .48 n.d. .000 32.538 99.9
121 21.0 29.8 16.2 .50 n.d. .000 32.733 100.1
122 21.1 30.1 15.9 .46 n.d. .000 32.503 100.1
AVER: 20.9 30.0 16.0 .47 n.d. .000 32.544 99.88
SDEV: .116 .321 .183 .024 .008 .000 .209 .453
Best match in terms of stoichiometry appears to be CsZr2(PO4)3
formula units calculated on basis of 12 oxygens:
ELEM: Cs Zr P Hf Rb Si O SUM
116 .922 1.94 3.05 .014 n.d. .000 12.000 17.9
117 .935 1.93 3.06 .017 n.d. .000 12.000 17.9
118 .921 1.91 3.07 .016 n.d. .000 12.000 17.9
119 .928 1.98 3.02 .015 n.d. .000 12.000 17.9
120 .926 1.95 3.04 .016 n.d. .000 12.000 17.9
121 .925 1.91 3.07 .016 n.d. .000 12.000 17.9
122 .940 1.95 3.04 .015 n.d. .000 12.000 17.9
AVER: .928 1.94 3.05 .016 n.d. .000 12.000 17.93
SDEV: .007 .024 .020 .001 .001 .000 .000 .009
The stoichiometry doesn't work out perfectly, e.g. Cs should be 1 formula unit but is only 0.93. But we only had pollucite as Cs standard for calibration so if there's a problem with that standard this will also affect oxygen calculation by stoihiometry etc.
John
What is your preferred method to get a hundred bucks to you?
Cheers,
Malc.
Quote from: Malcolm Roberts on August 14, 2015, 12:45:56 AM
John
What is your preferred method to get a hundred bucks to you?
Cheers,
Malc.
Hi Malc,
I don't want your hundred bucks because I don't have the RbTiOPO4, but Marc Schrier does:
http://calchemist.com/contact.htm
Please contact him directly.
john
Anyone have any thoughts on alternative for Br? Something other than TlBr? We have just been pondering a synthetic scapolite with Br only. However, the thoughts are that this would probably need to be the Na end-member and may be a bit on the beam sensitive side. Others?
Quote from: Malcolm Roberts on August 20, 2015, 12:04:19 AM
Anyone have any thoughts on alternative for Br? Something other than TlBr? We have just been pondering a synthetic scapolite with Br only. However, the thoughts are that this would probably need to be the Na end-member and may be a bit on the beam sensitive side. Others?
Malcolm,
I completely concur with you. The community really needs some non water soluble beam stable halogen standards. I personally am looking for an iodine standard.
Maybe Marc Schrier can think of some such halogen compounds that might be synthesized for us?
john
Hi John,
I've been working on the Br "problem" with specific reference to scapolite and am going to go the 25kV route and use the ka line. It looks really good. Our Astimex block has TlBr/TlI in it so we can manage both of these halogens, however, I'd much rather have something better matrix matched. If Marc can come up with something, it would be great!!
Cheers,
Malc.
John,
In reply to your 8/10 post on the Cs/Zr/PO4 I prepared and sent up, sorry I've been such a flake; I've been swamped! The hope was that I would prepare an analog to the KTiOPO4 family, so just like the RbTiOPO4, but CsZrOPO4. I've not looked too hard, but it does not appear the phase has been prepared before. The two know Cs/Zr/PO4 phases I see in JCPDS are CsZr2(PO4)3 and Cs2Zr(PO4)2. We'd have to confirm by PXRD, but I think your probe analysis was correct, and the material is likely CsZr2(PO4)3. How did the material stand up to the beam? I'm pretty sure the sample I sent you was just powder, but if it was okay in the beam, then maybe that's just an easier target than going after an unknown phase. Is the Cs content getting too low? The Cs content in the other known phase, Cs2Zr(PO4)2, would be higher. I need to get the papers and see if they have already outlined a clear synthesis for crystals.
-Marc
Quote from: Marc Schrier on September 22, 2015, 12:44:45 PM
John,
In reply to your 8/10 post on the Cs/Zr/PO4 I prepared and sent up, sorry I've been such a flake; I've been swamped! The hope was that I would prepare an analog to the KTiOPO4 family, so just like the RbTiOPO4, but CsZrOPO4. I've not looked too hard, but it does not appear the phase has been prepared before. The two know Cs/Zr/PO4 phases I see in JCPDS are CsZr2(PO4)3 and Cs2Zr(PO4)2. We'd have to confirm by PXRD, but I think your probe analysis was correct, and the material is likely CsZr2(PO4)3. How did the material stand up to the beam? I'm pretty sure the sample I sent you was just powder, but if it was okay in the beam, then maybe that's just an easier target than going after an unknown phase. Is the Cs content getting too low? The Cs content in the other known phase, Cs2Zr(PO4)2, would be higher. I need to get the papers and see if they have already outlined a clear synthesis for crystals.
-Marc
Hi Mark,
The material you sent, let's call it CsZr2(PO4)3, was small crystals and seems very stable under the beam, just very small crystals.
If it is not water soluble I'd say we have our candidate Cs standard for bulk synthesis!
Do you have enough money around for starting materials, to try making some bigger crystals that I can better test for homogeneity, beam stability, etc.?
Malcolm and John, I have crystals of a series of Ti/IO3 compounds I prepared as an undergraduate that might work as an iodine standard; they are water insoluble. I'm not sure if they will stand up to the beam. John, I can send you some samples if you want to take a peek. There were a number of materials including H2Ti(IO3)6•2H2O, Ti(IO3)4, and TiO(IO3)2 and I should still have small samples of each.
-Marc
Quote from: Marc Schrier on September 22, 2015, 01:10:15 PM
Malcolm and John, I have crystals of a series of Ti/IO3 compounds I prepared as an undergraduate that might work as an iodine standard; they are water insoluble. I'm not sure if they will stand up to the beam. John, I can send you some samples if you want to take a peek. There were a number of materials including H2Ti(IO3)6•2H2O, Ti(IO3)4, and TiO(IO3)2 and I should still have small samples of each.
-Marc
The ones without water sound very interesting. Please send them to my UofO address. Thanks!
john
Quote from: Probeman on September 22, 2015, 12:50:18 PM
Hi Mark,
The material you sent, let's call it CsZr2(PO4)3, was small crystals and seems very stable under the beam, just very small crystals.
If it is not water soluble I'd say we have our candidate Cs standard for bulk synthesis!
Do you have enough money around for starting materials, to try making some bigger crystals that I can better test for homogeneity, beam stability, etc.?
But CsZr2(PO4)3 only contains about 23.5 wt% Cs2O. Natural pollucites contain up to about 40 wt% Cs2O, and it would be nice to have a standard that could be used to analyze for Cs in them (other than another pollucite).
Quote from: Brian Joy on September 23, 2015, 03:30:20 PM
Quote from: Probeman on September 22, 2015, 12:50:18 PM
Hi Mark,
The material you sent, let's call it CsZr2(PO4)3, was small crystals and seems very stable under the beam, just very small crystals.
If it is not water soluble I'd say we have our candidate Cs standard for bulk synthesis!
Do you have enough money around for starting materials, to try making some bigger crystals that I can better test for homogeneity, beam stability, etc.?
But CsZr2(PO4)3 only contains about 23.5 wt% Cs2O. Natural pollucites contain up to about 40 wt% Cs2O, and it would be nice to have a standard that could be used to analyze for Cs in them (other than another pollucite).
Hi Brian,
You are correct that we would have a raw k-ratio of somewhat under 2 for the matrix correction if we utilized this material as a Cs standard for a high Cs pollucite characterization (actually k-raw = 1.75 in the example below, which I feel is an extrapolation within reason). I do not know how valuable a number the Cs content of a pollucite mineral is geologically and I defer to your expertise on this matter of course.
In any case this Cs standard was/is primarily intended for use as a trace element standard, and of course for this purpose, it almost doesn't matter what we use as a standard, so long as it is stable under the beam (and not water soluble would be nice). :)
That said, we can examine the matrix correction magnitudes for these two materials and here is our proposed synthetic:
ELEMENT ABSCOR FLUCOR ZEDCOR ZAFCOR STP-POW BKS-COR F(x)u Ec Eo/Ec MACs
Cs la .9985 1.0000 1.2158 1.2140 1.4193 .8567 .9064 5.0120 2.9928 385.778
Zr la 1.0414 .9984 1.0941 1.1377 1.2284 .8907 .7609 2.2230 6.7476 964.694
P ka 1.2197 .9988 .9322 1.1357 .8687 1.0731 .7529 2.1460 6.9897 1000.49
O ka 3.4599 .9998 .8284 2.8655 .7452 1.1116 .2025 .5317 28.2114 7450.29
ELEMENT K-RAW K-VALUE ELEMWT% OXIDWT% ATOMIC% FORMULA KILOVOL
Cs la .00000 .18238 22.142 ----- 5.556 .167 15.00
Zr la .00000 .26715 30.393 ----- 11.111 .333 15.00
P ka .00000 .13630 15.480 ----- 16.667 .500 15.00
O ka .00000 .11162 31.986 ----- 66.667 2.000 15.00
TOTAL: 100.000 ----- 100.000 3.000
And here is a natural pollucite from Rossman with a high Cs concentration:
ELEMENT ABSCOR FLUCOR ZEDCOR ZAFCOR STP-POW BKS-COR F(x)u Ec Eo/Ec MACs
Cs la .9648 1.0000 1.2478 1.2038 1.4785 .8439 .9381 5.0120 2.9928 250.373
Si ka 1.5404 .9989 .9203 1.4161 .8678 1.0606 .5879 1.8390 8.1566 1974.48
Al ka 1.7391 .9925 .9451 1.6313 .8841 1.0690 .5102 1.5600 9.6154 2557.00
Na ka 2.8865 .9977 .9325 2.6853 .8611 1.0829 .2916 1.0730 13.9795 5371.51
O ka 2.0263 .9996 .8511 1.7239 .7787 1.0931 .3458 .5317 28.2114 4171.30
ELEMENT K-RAW K-VALUE ELEMWT% OXIDWT% ATOMIC% FORMULA KILOVOL
Cs la .00000 .32090 38.630 ----- 8.000 .167 15.00
Si ka .00000 .11529 16.326 ----- 16.000 .333 15.00
Al ka .00000 .04807 7.842 ----- 8.000 .167 15.00
Na ka .00000 .02488 6.682 ----- 8.000 .167 15.00
O ka .00000 .17534 30.227 ----- 52.000 1.083 15.00
H .293 ----- 8.001 .167
TOTAL: 100.000 ----- 100.000 2.083
As you can see, the difference in the matrix corrections is under 1%, so I don't think it is a significant concern even for major element analytical work. In fact the difference in the matrix corrections is probably smaller than the uncertainty in the Cs concentration in existing natural pollucite standards... I'm guessing.
Of course there is also the statistics of the extrapolation, but a factor of less than 2 should still provide reasonable analytical sensitivity.
Please feel free to explain further if I have missed your point.
john
Quote from: Probeman on September 23, 2015, 07:30:32 PM
In any case this Cs standard was/is primarily intended for use as a trace element standard, and of course for this purpose, it almost doesn't matter what we use as a standard, so long as it is stable under the beam (and not water soluble would be nice). :)
Hi John,
As far as I know, this is the first you've mentioned that this material was meant for use primarily as a trace element standard. I thought the idea was to produce standards that could be used for a variety of purposes? Pollucite is a particularly important mineral to characterize accurately because it is the major commercial source of Cs, and its Cs2O content is quite variable.
I am never comfortable with compositions that are significantly extrapolated. In the example you give, Cs La k-raw = 1.76, and this is excessive, especially for a major element. Also, while the total matrix correction is less than 1% (assuming that it's accurate), the component Z and A corrections are larger (~3%).
In my opinion -- for what it's worth -- it seems like a good idea to explore other possibly feasible candidates, such as Cs2Zr(PO4)2, before settling on CsZr2(PO4)3 for mass production. Respectfully, I think you're jumping the gun on this.
Brian
Quote from: Brian Joy on September 24, 2015, 06:27:13 AM
Quote from: Probeman on September 23, 2015, 07:30:32 PM
In any case this Cs standard was/is primarily intended for use as a trace element standard, and of course for this purpose, it almost doesn't matter what we use as a standard, so long as it is stable under the beam (and not water soluble would be nice). :)
Hi John,
As far as I know, this is the first you've mentioned that this material was meant for use primarily as a trace element standard. I thought the idea was to produce standards that could be used for a variety of purposes? Pollucite is a particularly important mineral to characterize accurately because it is the major commercial source of Cs, and its Cs2O content is quite variable.
I am never comfortable with compositions that are significantly extrapolated. In the example you give, Cs La k-raw = 1.76, and this is excessive, especially for a major element. Also, while the total matrix correction is less than 1% (assuming that it's accurate), the component Z and A corrections are larger (~3%).
In my opinion -- for what it's worth -- it seems like a good idea to explore other possibly feasible candidates, such as Cs2Zr(PO4)2, before settling on CsZr2(PO4)3 for mass production. Respectfully, I think you're jumping the gun on this.
Brian
Hi Brian,
I got you. Well let's not argue about what constitutes "excessive extrapolation".
I really don't care what the Cs standard ends up being (it could even be more than one compound!), so long as it's stoichiometric, beam stable, and not water soluble.
Marc was trying to grow CsZrOPO4 but got CsZr2(PO4)3 instead. That means to me that CsZr2(PO4)3 is "easier" to synthesize than the other. But what do I know.
Let's see what Marc Schrier says...
Hi Guys, I've not had a chance to do anything more on the Cs standard front, so there is not much to report. I will try to get the papers on the two Cs/Zr/PO4's, and I hope it sheds some light on the Cs:PO4 flux ratios and the product obtained. CsZr2(PO4)3 is 22.1% Cs while Cs2Zr(PO4)2 is 48.6% Cs, so I'm liking the higher Cs content of the latter. Antony sent me the paper for the CsAlTiO4 (48.9% Cs) and it's doable, but it sounds like it requires long run times at high temperatures in sealed platinum tubes. I'll have to see if someone has come up with a flux route to CsAlTiO4 as that would be much more amenable to crystal growth. -Marc
Quote from: Marc Schrier on October 14, 2015, 03:40:36 PM
Hi Guys, I've not had a chance to do anything more on the Cs standard front, so there is not much to report. I will try to get the papers on the two Cs/Zr/PO4's, and I hope it sheds some light on the Cs:PO4 flux ratios and the product obtained. CsZr2(PO4)3 is 22.1% Cs while Cs2Zr(PO4)2 is 48.6% Cs, so I'm liking the higher Cs content of the latter. Antony sent me the paper for the CsAlTiO4 (48.9% Cs) and it's doable, but it sounds like it requires long run times at high temperatures in sealed platinum tubes. I'll have to see if someone has come up with a flux route to CsAlTiO4 as that would be much more amenable to crystal growth. -Marc
Hi Marc,
I guess my preference would be to try to grow bulk quantities of the easiest material (with a relatively high concentration of Cs).
Since you already made some CsZr2(PO4)3 material, is that evidence that it is the easiest thing to grow? I always like easy. :)
I know we'd all like to see some progress here... do you need more funds to start some larger batches? What can we do to help?
I started the Cs/Zr/PO4 running again with some additional Cs; maybe that will push it over to the Cs2Zr(PO4)2 phase. I can probably get a friend to collect PXRD data on the crystals next time so we know what phase it made. And I've got some Chlorapatite I started to dabble with running at the same time. I'll let you guys know when I get something more. At this point I don't think there is much you guys can do to help... the time I can spend on this side project will unfortunately be quite variable... -Marc
Quote from: Marc Schrier on October 15, 2015, 01:50:14 PM
I started the Cs/Zr/PO4 running again with some additional Cs; maybe that will push it over to the Cs2Zr(PO4)2 phase. I can probably get a friend to collect PXRD data on the crystals next time so we know what phase it made. And I've got some Chlorapatite I started to dabble with running at the same time. I'll let you guys know when I get something more. At this point I don't think there is much you guys can do to help... the time I can spend on this side project will unfortunately be quite variable... -Marc
Hi Marc,
I understand. If you think of something please let us know. I also know you're looking at some potential iodine standards and I will be happy to hit those with an electron beam, but right now the popularity contest here:
http://smf.probesoftware.com/index.php?topic=560.0
indicates that we should focus on the Cs standard first and foremost, and after that a synthetic fayalite (Fe2SiO4) would be awesome.
I was just wondering if there has been any word from Marc regarding development of a Cs standard. Next week I'll have someone in the lab analyzing Rb- and Cs-bearing micas, and so I'll get to put the very nice RbTiOPO4 standard to use.
Quote from: Brian Joy on March 18, 2016, 09:23:06 AM
I was just wondering if there has been any word from Marc regarding development of a Cs standard. Next week I'll have someone in the lab analyzing Rb- and Cs-bearing micas, and so I'll get to put the very nice RbTiOPO4 standard to use.
Hi Brian,
I sent them a reminder as I haven't heard anything- will let you know.
In the meantime I do have some of the CsZr2(PO4)3 material they grew for me as a trial Cs standard. Should be fine as a trace element standard.
john
Quote from: Owen Neill on March 18, 2016, 04:58:04 PM
Brian - a note of caution that there may be grains of RbTiOAsO4 in with the RTP. In hand specimen they look almost exactly alike, but they'll be very different in BSE (see attached PDF), so any stray RTA grains should be easy to avoid, if you have any. They appear to be separate crystals rather than inclusions of one phase within another.
Hi Owen,
Is this the UC Berkeley RbTiOPO4, Astimex RbTiOPO4 or the RbTiOPO4 from CalChemist?
john
Quote from: Owen Neill on March 18, 2016, 05:17:25 PM
Quote from: John Donovan on March 18, 2016, 05:06:48 PM
Hi Owen,
Is this the UC Berkeley RbTiOPO4, Astimex RbTiOPO4 or the RbTiOPO4 from CalChemist?
john
Hi John,
CalChemist - purchased from Marc Schrier in July 2015.
That material was obtained as a single crystal from a laser optics company which was in several slices off the sides of a large boule.
I measured the traces in a piece of it as shown here (obviously the Na background has a problem, probably an off-peak interference):
Un 7 RbTiOPO4
TakeOff = 40.0 KiloVolt = 20.0 Beam Current = 100. Beam Size = 5
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 1000, Magnification (imaging) = 1000)
Image Shift (X,Y): .00, .00
Number of Data Lines: 7 Number of 'Good' Data Lines: 7
First/Last Date-Time: 06/11/2015 09:37:16 AM to 06/11/2015 01:14:15 PM
WARNING- Using Exponential Off-Peak correction for cs la
WARNING- Using Exponential Off-Peak correction for na ka
Average Total Oxygen: .000 Average Total Weight%: 100.015
Average Calculated Oxygen: .000 Average Atomic Number: 21.781
Average Excess Oxygen: .000 Average Atomic Weight: 30.549
Average ZAF Iteration: 2.00 Average Quant Iterate: 2.00
Un 7 RbTiOPO4, Results in Elemental Weight Percents
ELEM: K Cs Na Ca Mg Rb Ti P O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC SPEC SPEC
BGDS: LIN EXP EXP LIN LIN
TIME: 400.00 400.00 400.00 400.00 400.00 --- --- --- ---
BEAM: 100.94 100.94 100.94 100.94 100.94 --- --- --- ---
ELEM: K Cs Na Ca Mg Rb Ti P O SUM
360 .015 .013 -.014 .000 -.001 34.979 19.604 12.676 32.741 100.014
361 .016 .012 -.016 .000 -.001 34.979 19.604 12.676 32.741 100.012
362 .016 .015 -.012 .000 .000 34.979 19.604 12.676 32.741 100.019
363 .015 .013 -.017 .000 -.002 34.979 19.604 12.676 32.741 100.010
364 .016 .015 -.010 .000 .000 34.979 19.604 12.676 32.741 100.021
365 .015 .013 -.012 .000 .000 34.979 19.604 12.676 32.741 100.017
366 .016 .012 -.013 .000 -.001 34.979 19.604 12.676 32.741 100.014
AVER: .016 .014 -.013 .000 -.001 34.979 19.604 12.676 32.741 100.015
SDEV: .000 .001 .003 .000 .001 .000 .000 .000 .000 .004
SERR: .000 .000 .001 .000 .000 .000 .000 .000 .000
%RSD: 2.86 9.44 -18.91 273.41 -74.31 .00 .00 .00 .00
STDS: 374 1125 336 358 358 --- --- --- ---
STKF: .1102 .2652 .0583 .1676 .0644 --- --- --- ---
STCT: 8027.8 14411.6 630.3 6846.5 3948.1 --- --- --- ---
UNKF: .0001 .0001 .0000 .0000 .0000 --- --- --- ---
UNCT: 9.9 6.3 -.5 .1 -.2 --- --- --- ---
UNBG: 44.7 162.4 7.8 37.9 23.0 --- --- --- ---
ZCOR: 1.1551 1.1603 2.6938 1.0543 1.8504 --- --- --- ---
KRAW: .0012 .0004 -.0009 .0000 -.0001 --- --- --- ---
PKBG: 1.22 1.04 .93 1.00 .99 --- --- --- ---
I did not notice any contamination. How odd. I'm going to look at my material again next week in BSE.
It could be from a contaminated edge of the boule maybe?
john
The RTP material I got from Marc consisted of a single chunk. The portion of it that I've mounted appears to be very homogeneous; the arsenate does not appear to be present. The only impurities I can find in easily detectable concentrations are K and Ca; the concentration of K2O is very consistently around 200 ppm, while CaO is around 100 ppm. I see no evidence of Cs in wavelength scans or in quantitative analyses (using LiF to avoid interference from Ti Ka).
(https://smf.probesoftware.com/gallery/381_19_03_16_2_06_32.bmp)
In measuring Na Ka, I operated in differential mode (lower purple curve) to suppress interference from P Ka(2) and P Kb(2) at the background offset positions (which I set to the low-L and high-L side, respectively, of the interfering line in order to avoid excessive background curvature).
(https://smf.probesoftware.com/gallery/381_19_03_16_8_44_13.bmp)
Hi Brian,
Your ~200 PPM of K corresponds nicely with my 160 +/- 10 PPM quant measurement. My Cs measurement may be problematic because I used a PET crystal and the Cs La peak is at a very low sin theta position for this diffractor. I was counting 400 seconds on peak and 400 seconds off-peak but the shape of the background is critical at these low spectrometer angles!
However, this is a wonderful opportunity to discuss trace element interpretation! I'll start a new topic for this in the PFE board, but in the meantime I concur that 2nd order P K lines are the problem with the Na measurement as seen here (exponential fit):
(https://smf.probesoftware.com/gallery/1_19_03_16_8_59_49.png)
This situation begs for the multi-point background method because it is difficult to predict these off-peak interferences ahead of time!. Here are the estimated sensitivities for single points and the t-test on the average:
Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):
ELEM: K Cs Na Ca Mg
360 .001 .002 .006 .001 .001
361 .001 .002 .006 .001 .001
362 .001 .002 .006 .001 .001
363 .001 .002 .006 .001 .001
364 .001 .002 .006 .001 .001
365 .001 .002 .006 .001 .001
366 .001 .002 .006 .001 .001
AVER: .001 .002 .006 .001 .001
SDEV: .000 .000 .000 .000 .000
SERR: .000 .000 .000 .000 .000
Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):
ELEM: K Cs Na Ca Mg
60ci .000 .000 .001 .000 .000
80ci .000 .001 .001 .000 .000
90ci .000 .001 .002 .000 .000
95ci .000 .001 .002 .001 .000
99ci .000 .002 .004 .001 .001
Note that potassium is quite easy to detect in this matrix, the 99% confidence interval for K is less than 10 PPM at 400 seconds on-peak/off-peak! While even with this integration time the Na 99CI t-test is still 40 PPM.
Here is the new topic:
http://smf.probesoftware.com/index.php?topic=701.msg4268#msg4268
I screwed up labeling of peaks on the PETH wavelength scan in my post about impurities in RbTiOPO4 from Calchemist. I accidentally labeled Ca Ka as K Kb, and so I've corrected it in the original post. The K Kb peak is barely visible. I should have posted about my results when they were fresh in my mind last summer.
Quote from: Brian Joy on March 19, 2016, 02:16:32 PM
I screwed up labeling of peaks on the PETH wavelength scan in my post about impurities in RbTiOPO4 from Calchemist. I accidentally labeled Ca Ka as K Kb, and so I've corrected it in the original post. The K Kb peak is barely visible. I should have posted about my results when they were fresh in my mind last summer.
Hi Brian,
This is getting "interestinger and interestinger".
You ran 1.7 sec dwell time and saw a Ca peak, but my Ca wavescan with 6 sec dwell time did not see any Ca and my Ca quant gave 0 +/- 10 PPM precision.
Did you quant Ca (and Mg)? If so, what did you get?
I'm going to hit this hard tomorrow and get to the bottom of it- multi-point backgrounds and all! I'll also measure Ti and P so I can do an interference correction for Ti on Cs and P on K.
john
Hi John,
I collected 88 analyses of RTP on a grid measuring approximately 5.5 x 3.9 mm. I analyzed for Ca, Na, K, and Cs using a 15 kV potential, 100 nA beam current, and 10-micron beam diameter; respective standards were anorthite, albite, adularia, and pollucite. I counted for 120 s peak and 120 s background for each element and interpolated linearly between background offsets. I used LiF to measure Cs La in order to eliminate interference from Ti Ka. As I noted above, I applied pulse amplitude discrimination to suppress interference from P Ka(2) and P Kb(2) at the Na Ka background offset positions. Average concentrations and standard deviations were: CaO, 108 and 18 ppm; Na2O, 44 and 19 ppm; K2O, 202 and 13 ppm. For Cs2O, I ended up with average k-ratio = -0.000053. For each of the oxides CaO, Na2O, K2O, and Cs2O, I calculate respective detection limit (3 std deviations above background) of 37, 67, 33, and 600 ppm for a given analysis. The only trace elements I could "see" in wavelength scans were K and Ca.
Hi Guys, here are some answers to the last few posts; sorry for the tardy reply. Brian, as for news on a Cs standard, I've been completely swamped on a project and have had no time to do any more work on it. A friend is working on it now, but I have not heard if he has had any success yet. The CsZr2(PO4)3 John has were very small crystals. I have some more of what should be the same phase from later runs, but I never got the crystals any bigger. Owen, as John said, I'm pretty sure the RTP was all one very large crystal. Actually it went to John who I think sliced it, so when I got it, there were two or three parts. I tried to break it up as gently as possible in a clean mortar with a pestle, and from that I've doled out the 1 g portions into new plastic screw top tubes. The material has not been sieved or anything similar that might introduce grains from another material, so I cannot explain the As-containing grains. John, did it indeed come as one crystal (and you guys sliced it), or might those slices have been RTA that's now mixed in? Yikes! -Marc
Quote from: Marc Schrier on March 20, 2016, 02:26:20 PM
Hi Guys, here are some answers to the last few posts; sorry for the tardy reply. Brian, as for news on a Cs standard, I've been completely swamped on a project and have had no time to do any more work on it. A friend is working on it now, but I have not heard if he has had any success yet. The CsZr2(PO4)3 John has were very small crystals. I have some more of what should be the same phase from later runs, but I never got the crystals any bigger. Owen, as John said, I'm pretty sure the RTP was all one very large crystal. Actually it went to John who I think sliced it, so when I got it, there were two or three parts. I tried to break it up as gently as possible in a clean mortar with a pestle, and from that I've doled out the 1 g portions into new plastic screw top tubes. The material has not been sieved or anything similar that might introduce grains from another material, so I cannot explain the As-containing grains. John, did it indeed come as one crystal (and you guys sliced it), or might those slices have been RTA that's now mixed in? Yikes! -Marc
Hi Marc,
It came as several small slices from the sides of a large boule. We broke off one piece for my trace element analyses. It's possible there were some small grains of another phase adhering to the RbTiOPO4 slices that came from the laser optics company who sent it to us. I suppose these tiny crystals could have gotten into the vials when Marc poured the pieces in.
Marc: I've written to Mark repeatedly, but I'm getting no response on the Cs synthesis. How can this project be moved forward? At this point we just need a rough quote for the cost of producing an initial production run of say 1 or 2 grams...
john
Jared Singer just reported to me his 2nd round of ICP-MS laser ablation numbers on the RbTiOPO4 standard material available from the Calchemist site for $100/gram:
"All numbers in ppm; average of four distinct grains, three spots each; standard deviation of 12 replicates; average from last time in parentheses for comparison.
Na = 0 ± 3 (0)
Mg = 23 ± 1 (0)
Si = 520 ± 70 (400)
S = 120 ± 20 (80)
Cl = 265 ± 40 (130)
K = 155 ± 15 (150)
Ca = 10 ± 10 (0)
As = 51 ± 4 (115)
Cs = 8 ± 1 (9)
Like last time, there was one outlier grain with very high potassium (2000 ± 300ppm). Some grains of arsenate previously noted, but avoided this time around."
These numbers seem to agree very nicely with the latest EPMA results that I posted previously:
Un 4 CalChemist RbTiOPO4 #2, Results in Elemental Weight Percents
ELEM: K Cs Na Ca Mg Ti P Rb O
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: MULT MULT MULT MULT MULT EXP EXP
TIME: 320.00 320.00 400.00 400.00 400.00 80.00 80.00 --- ---
BEAM: 99.63 99.63 99.63 99.63 99.63 99.63 99.63 --- ---
ELEM: K Cs Na Ca Mg Ti P Rb O SUM
37 .018 .002 .001 .003 .000 19.428 12.506 34.979 32.741 99.677
38 .017 .002 .000 .003 .000 19.454 12.521 34.979 32.741 99.719
39 .017 .003 .000 .001 -.001 19.486 12.505 34.979 32.741 99.731
40 .018 .003 .001 .003 .000 19.517 12.542 34.979 32.741 99.803
41 .019 .001 .002 .004 .001 19.466 12.499 34.979 32.741 99.711
42 .018 .002 -.002 .002 -.001 19.447 12.511 34.979 32.741 99.698
43 .018 .001 .001 .002 -.001 19.472 12.568 34.979 32.741 99.780
44 .018 .000 .002 .002 .000 19.445 12.496 34.979 32.741 99.682
45 .018 .000 -.002 .002 .000 19.489 12.478 34.979 32.741 99.704
46 .018 -.002 .001 .003 .000 19.528 12.567 34.979 32.741 99.835
47 .018 .001 -.001 .003 -.001 19.489 12.543 34.979 32.741 99.772
48 .019 .002 .001 .002 -.001 19.507 12.506 34.979 32.741 99.756
AVER: .018 .001 .000 .002 .000 19.477 12.520 34.979 32.741 99.739
SDEV: .000 .002 .001 .001 .001 .031 .029 .000 .000 .050
SERR: .000 .000 .000 .000 .000 .009 .008 .000 .000
%RSD: 2.29 128.51 712.86 31.93 -247.65 .16 .23 .00 .00
STDS: 374 1125 336 358 358 22 1016 --- ---
STKF: .1102 .2652 .0583 .1676 .0644 .5616 .1496 --- ---
STCT: 9129.3 11088.8 1550.4 7022.5 3286.5 64371.5 4913.6 --- ---
UNKF: .0002 .0000 .0000 .0000 .0000 .1753 .0763 --- ---
UNCT: 12.9 .4 .0 .9 -.1 20095.1 2504.8 --- ---
UNBG: 45.8 156.1 11.1 40.4 22.7 132.4 7.6 --- ---
ZCOR: 1.1552 1.1604 2.6811 1.0545 1.8314 1.1110 1.6413 --- ---
KRAW: .0014 .0000 .0000 .0001 .0000 .3122 .5098 --- ---
PKBG: 1.28 1.00 1.00 1.02 1.00 152.73 330.98 --- ---
INT%: ---- -95.91 ---- ---- ---- ---- ---- --- ---
The full post is here:
http://smf.probesoftware.com/index.php?topic=701.msg4317#msg4317
I don't mean to brag (oh yes I do!), but Jared got 10 +/- 10 PPM of Ca, while the probe got 20 +/- 10 PPM.
In addition the ICP-MS got 8 +/- 1 PPM of Cs using laser ablation, and after all my finagling with the background and interference corrections (all performed before seeing the ICP-MS analyses!), the probe got 10 +/- 20 PPM by EPMA. At least the error bars overlap nicely! :)
I'm interested in developing (or obtaining) a synthetic topaz for general distribution to the community, but I'm curious if this mineral can exist without any OH. Does anyone know? Specifically I'm wondering if an end member topaz such as Al2SiO4F2 as opposed to Al2SiO4(F,OH)2 might be possible, since both F and OH are -1 valence, and also might be more beam resistant...
We all know that fluor-phlogopite is problematic because when mounted in epoxy it separates into very thin lamellae and fluor-apatite is very beam sensitive, so a synthetic pure topaz might be very useful, but is there any reason one couldn't use topaz as a standard for silicate characterization? I mean, are there peak shape or shift issues when using topaz as a fluorine standard for say amphiboles or biotites?
john
According to the attached paper (provided by Prokopiy Vasilyev), natural topaz can contain little or no OH.
Does anyone have any ideas or suggestions on who we might contact, that might have ideas on obtaining such as synthetic topaz for use as a F standard?
So I found this old, old paper about synthesizing anhydrous topaz (see attached). It comes out of the Washington State Lab so maybe we can have Owen hunt around if there is a jar of it (hahaha) standing around.
The paper gives some info on how to synthesize it and it needs a cold seal pressure vessel which we don't have here. However, it sounds that the experiments were quite lengthy and did not result in large grains necessarily.
Bernd Wunder at GFZ Potsdam synthesized OH-rich Topaz which is not what you are looking for. He may be the person to talk to nevertheless?
Quote from: John Donovan on September 24, 2015, 09:14:10 AM
Marc was trying to grow CsZrOPO4 but got CsZr2(PO4)3 instead. That means to me that CsZr2(PO4)3 is "easier" to synthesize than the other. But what do I know?
I got this info back from our crystallographer on the Cs material that Marc grew as a test case for us:
QuoteIt was expected as CsZrOPO4. Based on the X-ray structure it is Cs O12 P3 Zr2. The structure of the compound with the same formula was determined and published before as trigonal. This crystal is orthorhombic and seems to be different phase.
So "Cs O12 P3 Zr2" is also what I got from EPMA (CsZr2(PO4)3).
Attached below is his CIF file in case anyone is interested.
I recently made an official request for an agenda item at the next M&M this summer to Tom Kelly regarding MAS support of standard material development for the SEM/EPMA community. Here is my letter:
Hi Tom,
Ed Vicenzi suggested I request an agenda item on the possibility of the MAS society funding standard materials development for the next council meeting. Unfortunately I will not be attending the M&M conference this year. So I would like for you to present this as described below. I am aware that the FIGMAS group is already consolidating information on existing standards, but I feel that we do not need a year of study to realize that we have serious deficiencies in our standards for some critical elements (e.g., alkali metals, halogens, etc.). I propose:
1. The technique of x-ray emission quantification depends on high quality and sufficient quantities of standard materials. This is particularly true for WDS and I would argue for EDS as well (delete the standardless button!).
2. Most standard materials available from traditional sources (the Smithsonian for example), are natural materials with well documented issues of inclusions and variable composition, and are available only in "fly speck" quantities. Commercial standards are expensive and also problematic for similar reasons.
3. Today, synthetic single crystals of high purity (all traces below detection limits) that are stoichiometrically constrained by thermodynamics, can be produced in 0.1 to 1.0 kilogram quantities quite easily by those with expertise. Thus relieving us of the problems with "fly speck" quantities and variable compositions and/or inclusions in our standard materials. Every EPMA/SEM lab in the world should have a gram of these materials. Then we are all "on the same page" so to speak...
3. We have demonstrated that an ideal (beam stable, insoluble, stoichiometric and high purity), standard for Rb (RbTiOPO4), can be synthesized and is *already* available to all at $100/gram (such as deal). See here for details:
http://smf.probesoftware.com/index.php?topic=301.msg2872#msg2872
4. A effort to identify further possible candidates for synthesis has begun here (you must be logged in to see the poll results):
http://smf.probesoftware.com/index.php?topic=560.0
The current winner by popular demand is a cesium zirconyl phosphate which would be beam stable, insoluble in water and stoichiometric. A quotation from one synthesis firm will give the society 50 grams of material for $5K (or 100 grams for $10K). In other words we can break even on our investment at $100/gram! I don't really care where/who distributes these "community standards", but I think we need to start a program to begin this process even if it is one lonely standard material at a time!
5. A good use of the society's money is student support and decent food, but I would argue that standard development efforts are a seriously neglected area for a society whose flagship method (EPMA/SEM) is entirely dependent on high quality and readily available standards. As NIST will only produce glasses which are compositionally problematic (how do we know what we just made, and is it homogeneous?), single crystal synthesis seems a worthy cause to add to the society's mission.
What can we do to advance this agenda? I would be happy to discuss this by phone. Thanks for your support.
john
Here is Tom's reply:
Hi John,
This is an excellent idea and I thank you for advocating. I will indeed put this on the agenda and yes, please feel free to publicize this issue. I agree with your arguments.
We mainly will need to be sure that the finances and logistics work out and I assume that others in the community will agree with the sentiments you express here.
I will present this at Council.
Keep me informed.
Regards,
Tom
Comments/suggestions?
Here is Ed Vicenzi's response to my MAS council agenda item request:
Tom and John
I am happy this item will make its way on to the MAS summer council agenda. I would however advise that if this measure is adopted by the council that a discussion/survey monkey take place to ensure that the first MAS-subsidized material synthesized represents a priority community need. I understand there has been some prior discussion, but for many this will be the first time they have heard of the topic.
Cesium zirconyl phosphate has it's virtue as a selection, but it may not represent a community priority. Anecdotal I know, but during my own decades long career I have been engaged in exactly a single instance when Cs was an important part of a system of research interest. In a recent telephone discussion with John Donovan he mentioned that he did not care which material was synthesized for this purpose, only that the society should be involved in standard synthesis as a way of investing in/engaging the MAS membership. I want to see this happen, but I don't want to have Cs zirconyl phosphate produced as the first MAS-funded material if their are other more pressing needs, whatever they may be.
Ed
My response was :
I agree completely. Personally I'd prefer an end-member fayalite. Let's see what a survey says.
To which I would add: or a fluor-topaz synthetic! :D
Frankly, any "community sourced" standard material (broadly available), would be an improvement over what we have currently. I realize that there are commercial sources for standard materials, and many of these are fine, though not inexpensive. Likewise we have several non-profit materials available, but generally only in tiny quantities.
Maybe Cs isn't the best candidate standard material to develop first, though I would argue that we already know there is no broadly available, beam stable, non water-soluble, stoichiometric material currently available at the moment for Cs. And we have a recipe for its synthesis...
Yes, let's perform a MAS (sanctioned) survey of the next standard material that should be developed (as a community), and observe the consensus priority. How do we start that survey process (as a society)? I assume the MAS council would have to request such a survey...
Ed Vicenzi sent me this link which contains the recipe for synthetic fayalite:
http://www.minsocam.org/ammin/AM65/AM65_381.pdf
Marc and Mark: does this seem a feasible synthesis for your labs?
Hey John (and Ed),
Unfortunately neither myself or Mark are set up to do a Czochralski (Giant Crystal Growth). We're more accustomed to smaller crystals, and could potentially utilize the same conditions as a Czochralski growth without the sophisticated rotating and pulling apparatus. In this case, while the conditions (temp, pressure, gas, etc) are very doable, the flux is less than ideal for the way we tend to work. With FeO (reduced from Fe2O3) and SiO2 as the two ingredients, it would be difficult to isolate the Fayalite (Fe2SiO4) from the flux (maybe there is a sweet spot for an acid). More ideally we look for water soluble salts like the alkali halides and phosphates we can decant and then wash away from the crystals. Maybe it's worth pinging the authors to see if they have any old samples.
-Marc
Quote from: Marc Schrier on June 29, 2016, 03:58:36 PM
Hey John (and Ed),
Unfortunately neither myself or Mark are set up to do a Czochralski (Giant Crystal Growth). We're more accustomed to smaller crystals, and could potentially utilize the same conditions as a Czochralski growth without the sophisticated rotating and pulling apparatus. In this case, while the conditions (temp, pressure, gas, etc) are very doable, the flux is less than ideal for the way we tend to work. With FeO (reduced from Fe2O3) and SiO2 as the two ingredients, it would be difficult to isolate the Fayalite (Fe2SiO4) from the flux (maybe there is a sweet spot for an acid). More ideally we look for water soluble salts like the alkali halides and phosphates we can decant and then wash away from the crystals. Maybe it's worth pinging the authors to see if they have any old samples.
-Marc
I spoke with Lynn Boatner (not a co-author but involved with the project I think), about 5 years ago and at that time he told me the gram or so of Fe2SiO4 he sent me was the last piece at the lab. Besides which we would ideally like to produce 50 to 100 grams (or more!) for the community for the future.
Please remember, the idea with these potential standard materials is *not* to do a "one off" synthesis for a published paper, but rather to produce a significant quantity of pure stoichiometric material for distribution to the EPMA and SEM communities as primary standards.
That's why finding a commercial grower is the first step, but after not finding these materials in quantity on the market I hoped a custom synthesis lab such as yours or Mark's could be an alternative.
That is if we can get the Microbeam Analysis Society to make the necessary financial investment. Mark quoted $5K for 50 grams of the Cs zirconyl phosphate, so that is the sort of things we are interested in.
john
Synthesis by optical floating zone furnace is another option. Some colleagues from RSES have been successfully making single crystal Fo90 under controlled atmosphere.
Quote from: Jeremy Wykes on June 29, 2016, 07:42:25 PM
Synthesis by optical floating zone furnace is another option. Some colleagues from RSES have been successfully making single crystal Fo90 under controlled atmosphere.
Hi Jeremy,
I know that pure Mg2SiO4 is commercially available, but I've never seen pure Fe2SiO4. Could this method be used to synthesize end member fayalite?
The nice thing about end-members is that once you have one, you already know it's exact chemistry. :)
john
End-members are much easier to make via floating zone than intermediate compositions. I suspect floating zone fayalite is not common due to the need for controlled atmosphere. Liebenbergite and Co2SiO4 could be made the same way, possibly also willemite and tephroite.
Quote from: Owen Neill on June 30, 2016, 09:57:56 AM
A dissertation from RWTH describing a procedure for Co-olivine synthesis, possibly germane to this discussion.
http://publications.rwth-aachen.de/record/50831/files/Sazonov_Andrew.pdf
Or at least german to the discussion! :D
john
I've been selling standards, or more correctly "reference materials as a little sideline business since 1993. They are mostly single crystal natural minerals and I have nearly a thousand different materials, and many materials from multiple locations. Hundreds of classic locations are included in my inventory. Topaz, for example, is present in my stock from at least a dozen localities. I have all of Gerald Czmanske's (formerly of the USGS) sulfides and tellurides that he synthesized very carefully in hydrogen fused quartz tubes. Some have two phases so the actual stoichiometry is sometimes questionable.
At one time I listed all of these on my old Frontpage website, but when every host dumped Frontpage support, I never re-built my website. I am however, slowly rebuilding that site. If you are desperated for something, you are welcome to contact me. Standards suppliers are not happy with me since I sell them at reasonable prices (mostly $15 ea for a 400 uM grain).
As far as Cs is concerned, I'm wondering what is the problem with gem quality pollucite. I have galkaite and rhodizite in addition to pollucite.
I make a Rb bearing silicate glass, but it is a reference material only. I was quite interested to learn about the Rb,Ti phosphate, and would be willing to buy it at $100 per gram. Please point me in the direction of the source for that material.
New minerals and re-classification of existing species via hair splitting end member assignments is making it nearly impossible to stay current with IDs. Check Mindat.org and Webmineral.com for current descriptions of minerals new and old. Mineral people never use the term "apatite", for example. Apatite "group", sometimes, but the fastidious use carbonate apatite, fluorapatite and hydroxyl apatite. I have well identified examples of each. Cannonite is named for yours truly. I have five other new minerals that I brought to the mineral world.
Bart Cannon / Cannon Microprobe / Seattle
By the way, the OH analog of topaz has yet to be named by the International Mineralogical Association.
Quote from: Bart Cannon on July 12, 2016, 06:31:48 AM
As far as Cs is concerned, I'm wondering what is the problem with gem quality pollucite.
Hi Bart,
Well for one thing we are looking for 50 to 100 gram quantities of pure homogeneous material. Now you might reasonably ask: why would we want that much material? And my answer would be: so that every lab on the planet can have more than a "flyspeck" in their standard mounts, so that it can withstand repeated polishing... Also, for synthesis a tested recipe is necessary in order to avoid creating an entire research project. Do you have a recipe for synthetic pollucite?
Quote from: Bart Cannon on July 12, 2016, 06:31:48 AM
I make a Rb bearing silicate glass, but it is a reference material only. I was quite interested to learn about the Rb,Ti phosphate, and would be willing to buy it at $100 per gram. Please point me in the direction of the source for that material.
It's here:
http://smf.probesoftware.com/index.php?topic=301.msg2872#msg2872
Please note that this material is not for resale.
A good synthetic or well-characterized natural ilmenite standard would be nice to have. First, it's a common mineral that needs to be analyzed accurately, especially when trying to ascertain Fe2O3 content. Second, when I use rutile and hematite as respective Ti and Fe standards, I often get greater than one Ti atom per three-oxygen formula unit. Overestimation of TiO2 content and underestimation of FeO has been noted by others when using rutile and hematite as standards (see attached paper by Evans et al., p. 152 and appendix). The errors tend to offset and produce an oxide total near 100% and result in underestimation of Fe2O3 (from charge balance). Last, the only ilmenite standard available from the Smithsonian is USNM 96189, which is visibly inhomogeneous (see image below) and has an analysis total of only 99.4%. When I do wavelength scans, I don't see anything other than Ti, Fe, Mn, Mg, and Nb, which are all accounted for in the wet chemical analysis.
Does anyone know if it is relatively easy to synthesize ~100-micron ilmenite crystals, for instance by a reaction such as Fe + Fe2O3 + 3TiO2 = 3FeTiO3 in an evacuated silica glass tube?
Ilmenite USNM 96189:
(https://smf.probesoftware.com/gallery/381_24_10_16_7_28_12.bmp)