Hi Everyone,
I plan to analyze many (~50) apatite crystals spanning the full range of F and Cl proportions, and I am hoping for advice on an efficient quantitative protocol that includes several trace elements as well (e.g., La, Ce, Mn).
I have read Goldoff et al (2012, Am Min v97 p1103-1115) and Henderson (2011, U Michigan MS thesis), and I have spoken with several people on the topic. Most agree on these:
- c-axis parallel to beam
- large spot diameter (I'll try 10 microns)
- low current (I'll try 5-10 nA)
- 15 kV to get the REEs
- fresh surfaces (not damaged by previous analyses) on both standards and unknowns
However, it sounds like there are two camps on the topic of counting time:
- long counting times on the order of 10 minutes are required for quality results, especially for F-rich grains
- short counting times (30 or 60 seconds per element) with TDI correction give quality results even with F-rich compositions
I am mostly interested in advice on counting time (do you agree with 1 or 2?) but other thoughts are certainly welcome. Thanks!
(Instrument: JEOL 8200)
As long as you use a Time Dependent Intensity Correction (TDI), and perform that correction on *both* your unknowns and standards, you shouldn't be required to orient the crystals for quantification.
http://smf.probesoftware.com/index.php?topic=11.0
Hi,
I just finished a big batch of apatite analyses, the following is my routine for apatites in carbonatites and phonolites (so you may want/need other elements) on a JEOL 8900. Overall, I go with approach 2.
Analytical conditions: 15kV, 10 nA and a beam diameter of 15 µm
Element setup:
LDE1: F
PET: Ca, P, S, La, Ce, Cl
TAP: Si, Mg, Na, Sr
LIF: Fe, Mn
Counting times: 60/30 (Pk/bkgr) for F and Cl, 40/20 for Fe, all other 30/15
PFE specific settings:
Measurement options: TDI (but I only use it for F in the end; TDI also on the standards), Asynchronous mode, pick background position and models from a good wavescan
Analytical options: Halogen correction
I usually re-calibrate every six hours at least the apatite standard (Durango) to track any drift. I also carbon coat the standards together with the samples if possible.
Another good paper to read is also: Marks et al. 2012: The volatile inventory (F, Cl, Br, S, C) of magmatic apatite: An integrated analytical approach. Chemical Geology 291, 241 - 255.
I hope this helps. Enjoy your apatites!
Thanks for both of your replies. I'll let the forum know if I find anything else to add.
1) Durango apatite is heterogeneous and is thus not recommended as a standard. Instead, use F-topaz or MgF2 for the F standard. These two materials are much more robust than any fluorapatite and show very limited F decay with beam exposure. Synthetic MgF2 should be easy to find.
2) Performing TDI corrections on both the standard and unknown does not assure good results, since the shape of the TDI curve changes with sample crystallographic orientation. The TDI curve shapes are also complex and not conducive to fitting. Eliminate at least one source of error by using a robust standard (see above).
3) As Cl concentration increases, you have a better chance of getting good analyses, but I am skeptical of any results on fluorapatites, unless I know that the sample was analyzed with the beam perpendicular to the c-axis. If the sample is hexagonal, move on.
4) In general, there will be a systematic over-estimation of F with TDI back-calculation. The literature is full of EPMA apatite analyses with higher F concentrations than are possible in end-member fluorapatite.
Regards,
Carl
Quote from: chenderson on September 05, 2014, 12:17:30 PM
2) Performing TDI corrections on both the standard and unknown does not assure good results, since the shape of the TDI curve changes with sample crystallographic orientation. The TDI curve shapes are also complex and not conducive to fitting. Eliminate at least one source of error by using a robust standard (see above).
Hi Carl,
The reason for performing TDI curves on both the unknown and standard is *exactly* because the crystallographic orientation will generally be different between the unknown and standard!
Now the TDI extrapolation may not always be "conducive" to fitting, but compared to trying to orient one's unknowns to the same crystallographic orientation as the standard, it is quite easy. Also, PFE has an enormous number of TDI fitting options so one can usually do a very nice TDI extrapolation to zero time and Eric is using PFE.
Quote from: chenderson on September 05, 2014, 12:17:30 PM4) In general, there will be a systematic over-estimation of F with TDI back-calculation. The literature is full of EPMA apatite analyses with higher F concentrations than are possible in end-member fluorapatite.
Yes, true. But this is generally *not* due to the TDI overfitting, instead it is due to the matrix correction being miscalculated by assuming stoichiometric oxygen when the fluorine content is replacing some of that stoichiometric oxygen in the mineral.
How could this matter? Well F Ka is highly absorbed by oxygen, so if the matrix totals say, 106% due to excess stoichiometric oxygen, then the F concentration is overestimated by around 15%.
See here for details on this interesting (and unpublished!) method to automatically subtract the oxygen equivalence of all measured (or specified!) halogens during the matrix iteration:
http://smf.probesoftware.com/index.php?topic=81.msg292#msg292
For the above post, scroll all the way to the bottom for the halogen example.
http://smf.probesoftware.com/index.php?topic=8.msg1127#msg1127
Quote from: chenderson on September 05, 2014, 12:17:30 PM
1) Durango apatite is heterogeneous and is thus not recommended as a standard. Instead, use F-topaz or MgF2 for the F standard. These two materials are much more robust than any fluorapatite and show very limited F decay with beam exposure. Synthetic MgF2 should be easy to find.
Thanks for the input, Carl. I have both Durango Apatite and F-topaz. A previous user in our lab said that F in our F-topaz standard migrates much faster than Durango Apatite. I did not see the data myself, so I will do my own testing to be sure of the better standard. The heterogeneity in Durango Apatite is certainly a problem. Perhaps I will map our grains with hopes of finding a good portion of the standard (and then repolish).
Quote from: chenderson on September 05, 2014, 12:17:30 PM
... I am skeptical of any results on fluorapatites, unless I know that the sample was analyzed with the beam perpendicular to the c-axis. If the sample is hexagonal, move on.
The orientation debate is difficult to assess given that several studies seem to report different conclusions. However, many of my samples are already oriented – they come from a previous collection – so I don't have much choice anyway.
In Anette's post, she suggests asynchronous mode but in Probewin.pdf (e.g., p. 216, 218, 252) synchronous is the suggested mode when using the TDI correction. Has anyone noticed a significant difference between modes? I would like to keep the analysis fast so asynchronous is my preference, but not if it degrades the TDI correction significantly.
Thanks
Quote from: EricKelly on September 08, 2014, 12:02:37 PM
In Anette's post, she suggests asynchronous mode but in Probewin.pdf (e.g., p. 216, 218, 252) synchronous is the suggested mode when using the TDI correction. Has anyone noticed a significant difference between modes? I would like to keep the analysis fast so asynchronous is my preference, but not if it degrades the TDI correction significantly.
My word! Someone is actually reading the documentation! ;)
Actually I have to apologize because the documentation is slightly out of date on that point. It used to be that to get the interval between removing the faraday cup and starting the counting as short as possible, it was necessary to utilize synchronous mode. But not anymore.
It might also be true that this interval is now still slightly shorter using synchronous mode, but I believe that the asynchronous mode is almost as fast if not as fast.
Try turning on the "Debug Mode" and "Time Stamp Mode" in the Output menu and see exactly what the timing differences are- would be worth as post.
I should also note that some investigators such as Stuart Kearns rightfully warn of a non-linearity in the first few seconds of counting in some alkali glasses because the Na and K ion migration doesn't really get starting until the sample heats up from beam exposure. See here for more discussion:
http://smf.probesoftware.com/index.php?topic=116.msg454#msg454
Not sure if that applies to F in apatites though...
Hi all
Quick question with regards to MgF2. Where have people sourced this from? I can easily find MgF2 on chemical companies like Sigma Aldrich, but should I be concerned about the purity? Should I be trying to source a single crystal of MgF2?
In addition, has anyone had any success using the Uni of Edin REEFluoride glasses as F standards for apatite analyses?
Cheers
MTI corp has substrates that would be good for standard material:
http://www.mtixtl.com/crystalssubstratesa-z.aspx
Single crystal, oriented, high purity (99.99%).
Unfortunately, many of the substrates must be purchased in multiples of 4 or more. Are any other labs interested in this material? Our standard collection is so dire that I am thinking of getting most of the simple oxide substrates.
Interesting link. Thanks Jeremy, I will have a peruse of that website.
Also to all, with regard to my earlier question about the Uni of Edin REE Fluoride glasses....ignore that, I had a brain fade, they are silicate glasses. However I know Astimex has some LREE Fluoride glasses (which we have). Apart from purity/stoichiometry issues, does anyone have a feeling for F migration in REE fluorides?
Cheers
Thanks Owen. Unfortunately we don't have MgF2 on our Taylor block, but we do have PbF2, SrF2, and BaF2 on it. Sounds like I will have to do some TDI tests on these and the Astimex REE F2 to see if any of them are suitable.
Ah yeah, didn't think of that. Looking at the MACS it lookes like BaF2 and possibly the REEF2 might be the best of a bad bunch out of that lot. But yes, if you are listening Jeremy, I would be interested in getting some MgF2 from that company if you wanted to go in together. I will have a proper look at the website and see if there is anything else we might need.
Thanks all.
I have contacted them about getting raw material that is not wafered, oriented, polished or clean room packed.
Let me know what phases you are interested in and I will add that to my list.
Hi Jeremy
I had a good look and made a list, looked at the prices and cut some off the list...so I am left with MgF2, TiO2, SiO2, and YVO4. That would be great if you could add them to the list.
Cheers
Hello,
An alternative source of high-purity MgF2 is Sigma-Aldrich, catalog number 378836: "Magnesium fluoride, random crystals, optical grade, ≥99.99% trace metals basis, Synonym: Sellaite". A quantity of 5 grams is available for $128 (Cdn), before an academic discount, if any.
Best regards,
Andrew
I am revisiting this topic to post our new protocol for apatite, which might be useful to others. The most notable part of this is that our biggest improvement came from obtaining new standards.
After getting poor results from Utah Topaz, Fluorite, or Durango Apatite as primary standards for F, we obtained MgF2 (Sigma-Aldrich, 378836 - Thanks for the tip Andrew) and saw big improvements. We also obtained several of the Schettler et al. (2011, American Mineralogist v96 p138-152) synthetic apatite crystals for Ca, P, and Cl. Our APS-26 grain works well as a primary standard. We tried several others for use as secondary standards and found that APS-27 worked well. Durango apatite now serves as a secondary standard in our lab (This seems to be another example of Durango's variability, given that it works as a primary standard in some labs and not others).
Our goal was to develop a fast protocol to handle a large number of grains. For those grains that require better analyses, we will return to them with longer counting times and fewer trace elements. Starting with Anette's protocol and other comments from the forum, we now use the following on our JEOL 8200:
Analytical conditions:
15 kV
10 nA
10 micron spot diameter
Crystal assignments:
LDE (with expanded slit): F
TAP: Na, Si
PETH/J: Ca, P, Cl, Sr, Ce, Nd
LIFH: Fe, Mn
Peak/background counting times:
F: 50/25
Cl, Na, and Si: 40/20
All others: 20/10 (or 30/15 for better analyses)
Frequency of background measurements:
F, Cl, Ca, P: Every analysis
All others: First analysis of a grain only (Nth backgrounds)
Other options:
We use an exponential fit for F backgrounds (and Ce)
We include TDI measurements, but for our samples typically Ca and F are the only elements that need a TDI fit, and Ca rarely needs it.
We use PFE's halogen correction (or apply our own correction).
We recalibrate every 12 hours or so using different spot locations on standards that contain migrating elements, but so far have not seen significant drift.
Thanks again for everyone's help.
I would urge extreme caution in using MgF2 as a standard for analysis of F in apatite. In this case the F Ka absorption correction is astronomically large, and hence the accuracy of the correction is not likely to be good. For instance, using PAP in conjunction with MAC values suggested by Pouchou and Pichoir (in Electron Probe Quantitation) and using 15 kV potential and 40 deg. takeoff angle, f(chi) for F Ka in MgF2 is 0.6090, while in Ca5(PO4)3F it is 0.1355. This produces an absorption correction factor of 4.494, i.e. a correction of ~350%. Any small error in MACs or in the phi(rho*z) model could affect calculated wt% F significantly. Not only is F Ka strongly absorbed by oxygen, but it is roughly equally strongly absorbed by Ca, as it is energetic enough to ionize Ca L1,2,3. For instance, comparison of F Ka f(chi) in MgF2 and CaF2 gives 0.6090 versus 0.2180. Other problems notwithstanding (TDI, for instance), if there ever were a case in which a "matrix match" were needed between standard and unknown, the analysis of F in apatite is it.
Also, when analyzing for F using LDE1, are you taking into account the overlap from P Ka(3)? If you are using pulse amplitude discrimination, have you verified that you have completely eliminated the contribution from P Ka? For instance, have you done a wavelength scan for F Ka in differential mode on a nominally F-free material such as Ca2P2O7 (calcium pyrophosphate), which has roughly similar wt% CaO and P2O5 as apatite?
Quote from: EricKelly on May 04, 2015, 07:56:51 PM
Other options:
We use an exponential fit for F backgrounds (and Ce)
We include TDI measurements, but for our samples typically Ca and F are the only elements that need a TDI fit, and Ca rarely needs it.
We use PFE's halogen correction (or apply our own correction).
Hi Eric,
Very nice. A couple of questions...
For F ka did you use a 40 or 60 angstrom LDE?
Can you provide some example output from PFE? I'm especially interested in the difference between the results with and without the halogen - oxygen equivalent correction.
Also maybe could you post a couple graphs of the TDI effects? I've seen some strange behavior there and wondered how your curves look.
Quote from: Brian Joy on May 05, 2015, 07:32:55 AM
I would urge extreme caution in using MgF2 as a standard for analysis of F in apatite. In this case the F Ka absorption correction is astronomically large, and hence the accuracy of the correction is not likely to be good. For instance, using PAP in conjunction with MAC values suggested by Pouchou and Pichoir (in Electron Probe Quantitation) and using 15 kV potential and 40 deg. takeoff angle, f(chi) for F Ka in MgF2 is 0.6090, while in Ca5(PO4)3F it is 0.1355. This produces an absorption correction factor of 4.494, i.e. a correction of ~350%. Any small error in MACs or in the phi(rho*z) model could affect calculated wt% F significantly. Not only is F Ka strongly absorbed by oxygen, but it is roughly equally strongly absorbed by Ca, as it is energetic enough to ionize Ca L1,2,3. For instance, comparison of F Ka f(chi) in MgF2 and CaF2 gives 0.6090 versus 0.2180. Other problems notwithstanding (TDI, for instance), if there ever were a case in which a "matrix match" were needed between standard and unknown, the analysis of F in apatite is it.
Also, when analyzing for F using LDE1, are you taking into account the overlap from P Ka(3)? If you are using pulse amplitude discrimination, have you verified that you have completely eliminated the contribution from P Ka? For instance, have you done a wavelength scan for F Ka in differential mode on a nominally F-free material such as Ca2P2O7 (calcium pyrophosphate), which has roughly similar wt% CaO and P2O5 as apatite?
Hi Brian,
I think you make some good points.
On the standard for fluorine I suspect that a robust standard may be more import than the matrix match. Here are some comparisons between the Heinrich, Henke and FFAST MACs for these matrices:
MAC value for F ka in O = 12439.63 (LINEMU Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV)
MAC value for F ka in O = 12390.00 (CITZMU Heinrich (1966) and Henke and Ebisu (1974))
MAC value for F ka in O = 11927.75 (MAC30 Heinrich (Fit to Goldstein tables, 1987))
MAC value for F ka in O = 11863.62 (FFAST Chantler (NIST v 2.1, 2005))
MAC value for F ka in Ca = 12415.20 (LINEMU Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV)
MAC value for F ka in Ca = 12370.00 (CITZMU Heinrich (1966) and Henke and Ebisu (1974))
MAC value for F ka in Ca = 12623.93 (MAC30 Heinrich (Fit to Goldstein tables, 1987))
MAC value for F ka in Ca = 12132.31 (FFAST Chantler (NIST v 2.1, 2005))
MAC value for F ka in P = 5550.00 (LINEMU Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV)
MAC value for F ka in P = 5526.00 (CITZMU Heinrich (1966) and Henke and Ebisu (1974))
MAC value for F ka in P = 5219.60 (MAC30 Heinrich (Fit to Goldstein tables, 1987))
MAC value for F ka in P = 4905.57 (FFAST Chantler (NIST v 2.1, 2005))
The MAC for F ka by P is fairly small and the others are larger but in relative agreement, but I do think having a matrix match is ideal as you suggest.
I wonder if we should talk to Marc Schrier about the possibility of synthesizing an end member fluor-apatite? Wouldn't that be nice to have for everyone?
I already have a synthetic chlor-apatite (just a few grains left, but hydrothermally grown from the University of Nice, see Argiolas and Baumer, Can. Min., v. 16, pp 285-290, 1978), which is wonderful, though a little beam sensitive. Fortunately the Cl intensity doesn't seem to change much over time with mild beam conditions. I should also mention to Marc him synthesizing this in 100 - 200 gram quantities as well...
By the way, I received about 200 grams of RbTiOPO4 and after we analyze it for traces I will be sending it to Marc Schrier for distribution, so I'll let you know when that is ready.
Back to fluor-apatite though- the question isn't so much the size of the matrix correction relative to the standard, though it is worth considering, but the relative accuracy error on that correction is important I agree. Here is a comparison of two different matrix corrections on a fluor-apatite material (all using the same MACs) done by a student at the USGS so please ignore the accuracy! I also cut out most of the elements because she analyzed 36 elements in this standard!
First the JTA matrix correction (the default in my software):
ELEM: W Ta Fe Ti Nb Mn Na F SUM
100 .000 .000 .079 .000 .011 .037 .157 4.342 101.390
101 .000 .000 .000 .306 .000 .007 .130 3.655 100.569
102 .000 .000 .000 .000 .020 .038 .139 4.484 101.617
AVER: .000 .000 .026 .102 .011 .028 .142 4.160 101.192
SDEV: .000 .000 .045 .176 .010 .017 .014 .444 .551
SERR: .000 .000 .026 .102 .006 .010 .008 .256
%RSD: .16 .19 173.20 173.21 96.92 63.20 9.61 10.66
PUBL: n.a. n.a. n.a. n.a. n.a. n.a. .178 3.700 99.662
%VAR: --- --- --- --- --- --- -20.44 12.44
DIFF: --- --- --- --- --- --- -.036 .460
STDS: 468 467 7852 7840 442 7845 7815 8811
STKF: 1.0000 1.0000 .4985 .5548 1.0000 .1418 .0505 .1537
STCT: 602.94 622.84 44.65 43.13 135.92 13.23 52.31 16.58
UNKF: .0000 .0000 .0002 .0008 .0001 .0002 .0007 .0083
UNCT: -1.53 -.86 .01 .05 .00 .02 .68 .89
UNBG: 4.20 3.11 .29 .03 .27 .29 .80 .15
ZCOR: 1.1917 1.2114 1.1812 1.2234 1.2559 1.2066 2.1646 5.0168
KRAW: -.0025 -.0014 .0002 .0011 .0000 .0016 .0129 .0540
PKBG: .64 .72 1.04 .52 .99 1.08 1.85 7.21
INT%: 5.62 .30 ---- ---- ---- ---- ---- -18.21
And here is the original PAP (XPP) correction:
ELEM: W Ta Fe Ti Nb Mn Na F SUM
100 .000 .000 .079 .000 .012 .037 .153 4.386 101.453
101 .000 .000 .000 .307 .000 .007 .127 3.715 100.627
102 .000 .000 .000 .000 .022 .038 .136 4.549 101.685
AVER: .000 .000 .026 .102 .012 .028 .139 4.217 101.255
SDEV: .000 .000 .046 .177 .011 .017 .013 .442 .556
SERR: .000 .000 .026 .102 .006 .010 .008 .255
%RSD: .13 .15 173.20 173.21 96.94 63.20 9.43 10.48
PUBL: n.a. n.a. n.a. n.a. n.a. n.a. .178 3.700 99.662
%VAR: --- --- --- --- --- --- -22.07 13.96
DIFF: --- --- --- --- --- --- -.039 .517
STDS: 468 467 7852 7840 442 7845 7815 8811
STKF: 1.0000 1.0000 .4892 .5435 1.0000 .1383 .0485 .1498
STCT: 602.94 622.84 44.65 43.13 135.92 13.23 52.31 16.58
UNKF: .0000 .0000 .0002 .0008 .0001 .0002 .0006 .0081
UNCT: -1.53 -.86 .01 .05 .00 .02 .68 .90
UNBG: 4.20 3.11 .29 .03 .27 .29 .80 .15
ZCOR: 1.3693 1.3918 1.2122 1.2560 1.3782 1.2383 2.2085 5.2191
KRAW: -.0025 -.0014 .0002 .0011 .0000 .0016 .0129 .0540
PKBG: .64 .72 1.04 .52 .99 1.08 1.85 7.21
INT%: 5.62 .30 ---- ---- ---- ---- ---- -18.19
The matrix correction for F Ka goes from 5.0168 to 5.2191 so about 4% which is less than the relative standard deviation.
Also, the interference from P Ka III is important and I observe that on my Sx100, and it should be a slightly larger overlap on a JEOL instrument. For that of course we'd like to have a material with known P and no F, for instance the chlor-apatite standard I mentioned above. By the way, the above analyses are with the P III interference on F Ka corrected (see the line labeled INT% which is the interference correction percent which is ~18% so that is quite important as you mentioned.
Lots more to discuss here...
John, I found the paper at http://rruff.info/uploads/CM16_285.pdf Unfortunately I took Spanish in school, so I'm not doing really well with this French paper. Copying and pasting sections into a translator is giving me a sense for the paper, but not to enough detail yet. I do have a Leco Tem-Pres Reactor, so the 1-3000 bar and 200-850°C (I cannot go beyond 750°C) are possibilities. But... the reactor volume is just 28.2 cc, and if I use gold tubes like they did, it's dramatically less, so I would not get very much material. I did a search to see if I could find any other papers (hopefully one in English too), and I found several where chlorapatite was prepared from a molten flux, CaCl2. That's much more amenable to bulk syntheses! Two papers I saw were: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638812/ and http://journal.chemistrycentral.com/content/7/1/56 Are you guys familiar with chlorapatite prepared in this fashion? -Marc
Quote from: Marc Schrier on May 05, 2015, 07:05:42 PM
John, I found the paper at http://rruff.info/uploads/CM16_285.pdf Unfortunately I took Spanish in school, so I'm not doing really well with this French paper.
I'm pretty sure I found the paper in The Canadian Mineralogist... in English.
Quote from: Brian Joy on May 05, 2015, 07:32:55 AM
I would urge extreme caution in using MgF2 as a standard for analysis of F in apatite. In this case the F Ka absorption correction is astronomically large, and hence the accuracy of the correction is not likely to be good. For instance, using PAP in conjunction with MAC values suggested by Pouchou and Pichoir (in Electron Probe Quantitation) and using 15 kV potential and 40 deg. takeoff angle, f(chi) for F Ka in MgF2 is 0.6090, while in Ca5(PO4)3F it is 0.1355. This produces an absorption correction factor of 4.494, i.e. a correction of ~350%. Any small error in MACs or in the phi(rho*z) model could affect calculated wt% F significantly. Not only is F Ka strongly absorbed by oxygen, but it is roughly equally strongly absorbed by Ca, as it is energetic enough to ionize Ca L1,2,3. For instance, comparison of F Ka f(chi) in MgF2 and CaF2 gives 0.6090 versus 0.2180. Other problems notwithstanding (TDI, for instance), if there ever were a case in which a "matrix match" were needed between standard and unknown, the analysis of F in apatite is it.
Also, when analyzing for F using LDE1, are you taking into account the overlap from P Ka(3)? If you are using pulse amplitude discrimination, have you verified that you have completely eliminated the contribution from P Ka? For instance, have you done a wavelength scan for F Ka in differential mode on a nominally F-free material such as Ca2P2O7 (calcium pyrophosphate), which has roughly similar wt% CaO and P2O5 as apatite?
Hi Brian,
How appropriate that you responded – you were my TA at Davis!
I also prefer to matrix-match the standard to the unknown, but all of the other standards I've tried gave impossible F compositions (>4 wt%). Of course there may be something else wrong and the MgF2 standard fortuitously brings the F counts into alignment, but I haven't found anything else to blame. I am happy to hear more suggestions though.
Thanks for bringing up the P III peak issue. I think I've excluded it in my runs so far. Here are a couple of screenshots from a wavescan done on a nearly pure chlorapatite. The first image shows the location of the F peak, and the second shows the P peak.
(https://dl.dropboxusercontent.com/s/aalej7qjvwtlwf4/Wavescan1F.jpg?dl=0)
(https://dl.dropboxusercontent.com/s/stqv63s3vjqkn06/Wavescan2P.jpg?dl=0)
Quote from: Probeman on May 05, 2015, 11:48:41 AM
Quote from: EricKelly on May 04, 2015, 07:56:51 PM
Other options:
We use an exponential fit for F backgrounds (and Ce)
We include TDI measurements, but for our samples typically Ca and F are the only elements that need a TDI fit, and Ca rarely needs it.
We use PFE's halogen correction (or apply our own correction).
Hi Eric,
Very nice. A couple of questions...
For F ka did you use a 40 or 60 angstrom LDE?
Can you provide some example output from PFE? I'm especially interested in the difference between the results with and without the halogen - oxygen equivalent correction.
Also maybe could you post a couple graphs of the TDI effects? I've seen some strange behavior there and wondered how your curves look.
I don't remember off-hand which LDE crystal we have. I think the spacing is 60 but I'll have to check when I'm back on campus tomorrow.
Here are results from one of the synthetic standards (Schettler et al). The halogen correction gives slightly better results. I attached a longer print out in case anyone wants to see more.
Halogen corrected
TDI log-linear fit to FSt 209 Set 1 Apatite APS-27, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO O SUM
30 41.505 2.512 2.135 .043 .008 54.989 -3.039 98.151
31 41.652 2.442 2.192 -.076 .036 54.656 -3.023 97.879
32 42.261 2.350 2.158 .017 -.004 54.783 -2.976 98.588
33 42.090 2.350 2.158 -.008 -.009 54.980 -2.976 98.585
34 41.784 2.509 2.213 .046 .040 54.826 -3.056 98.362
35 42.034 2.321 2.164 -.039 .019 54.820 -2.965 98.353
36 42.011 2.518 2.129 .034 .028 55.012 -3.041 98.691
37 41.605 2.601 2.173 .014 -.010 55.114 -3.086 98.411
38 42.069 2.413 2.168 -.021 .034 55.166 -3.005 98.824
AVER: 41.890 2.446 2.166 .001 .016 54.927 -3.019 98.427
SDEV: .260 .095 .026 .041 .020 .166 .041 .288
SERR: .087 .032 .009 .014 .007 .055 .014
%RSD: .62 3.90 1.20 4609.42 127.17 .30 -1.35
PUBL: 41.863 2.472 2.290 n.a. n.a. 54.874 -1.500 100.000
%VAR: .06 -1.06 -5.42 --- --- .10 101.26
DIFF: .027 -.026 -.124 --- --- .053 -1.519
STDS: 211 206 211 42 39 211 0
(https://dl.dropboxusercontent.com/s/4tjagz4hb374j74/TDI%20APS-27.jpg?dl=0)
Without halogen correctionSt 209 Set 1 Apatite APS-27, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO O SUM
30 41.556 2.521 2.135 .043 .008 55.016 -1.500 99.778
31 41.703 2.451 2.193 -.076 .036 54.682 -1.500 99.489
32 42.310 2.359 2.158 .017 -.004 54.808 -1.500 100.148
33 42.139 2.358 2.159 -.008 -.009 55.005 -1.500 100.145
34 41.836 2.518 2.213 .046 .040 54.853 -1.500 100.006
35 42.082 2.329 2.164 -.039 .019 54.845 -1.500 99.901
36 42.062 2.527 2.130 .034 .028 55.038 -1.500 100.319
37 41.657 2.611 2.174 .014 -.010 55.141 -1.500 100.087
38 42.119 2.421 2.168 -.021 .035 55.192 -1.500 100.414
AVER: 41.940 2.455 2.166 .001 .016 54.953 -1.500 100.032
SDEV: .259 .096 .026 .041 .020 .167 .000 .282
SERR: .086 .032 .009 .014 .007 .056 .000
%RSD: .62 3.91 1.20 4608.25 127.17 .30 .00
PUBL: 41.863 2.472 2.290 n.a. n.a. 54.874 -1.500 100.000
%VAR: .18 -.70 -5.40 --- --- .14 .00
DIFF: .077 -.017 -.124 --- --- .079 .000
STDS: 211 206 211 42 39 211 0
Without the TDI fit (shown next), F matches the published value a bit more closely, but I think the slope is real so I use the TDI fit.
Halogen corrected
No TDI fitSt 209 Set 1 Apatite APS-27, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO O SUM
30 41.506 2.560 2.135 .043 .008 54.988 -3.059 98.179
31 41.653 2.498 2.192 -.076 .036 54.655 -3.046 97.911
32 42.263 2.490 2.158 .017 -.004 54.780 -3.035 98.668
33 42.092 2.462 2.158 -.008 -.009 54.978 -3.024 98.650
34 41.784 2.477 2.213 .046 .040 54.827 -3.042 98.343
35 42.035 2.384 2.164 -.039 .019 54.819 -2.992 98.389
36 42.010 2.475 2.129 .034 .028 55.012 -3.023 98.666
37 41.604 2.534 2.173 .014 -.010 55.115 -3.057 98.372
38 42.070 2.464 2.168 -.021 .034 55.165 -3.027 98.853
AVER: 41.891 2.483 2.166 .001 .016 54.926 -3.034 98.448
SDEV: .261 .049 .026 .041 .020 .167 .021 .292
SERR: .087 .016 .009 .014 .007 .056 .007
%RSD: .62 1.99 1.20 4607.13 127.17 .30 -.69
PUBL: 41.863 2.472 2.290 n.a. n.a. 54.874 -1.500 100.000
%VAR: .07 .41 -5.42 --- --- .09 102.28
DIFF: .027 .010 -.124 --- --- .052 -1.534
STDS: 211 206 211 42 39 211 0
Here is an example from our Durango standard. The TDI fit uses all but one obviously bad analysis. Note that the published value shown for F is probably wrong as the halogen site is overfilled. Other reports show about 3.3-3.4 wt% F.
St 60 Set 1 Apatite (Fluor) Durango, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO Na2O SiO2 SO3 As2O3 La2O3 Ce2O3 Pr2O3 Nd2O3 O SUM
21 41.098 3.102 .441 .017 .042 53.983 .187 .351 .370 .092 .468 .591 .060 .180 -1.400 99.582
22 40.498 3.544 .421 .029 .022 53.808 .187 .351 .370 .092 .468 .591 .060 .180 -1.582 99.039
23 40.862 3.298 .429 .023 .012 54.027 .187 .351 .370 .092 .468 .591 .060 .180 -1.480 99.469
25 40.764 3.894 .414 -.028 .004 54.163 .187 .351 .370 .092 .468 .591 .060 .180 -1.728 99.782
26 41.244 3.805 .418 -.040 .022 54.051 .187 .351 .370 .092 .468 .591 .060 .180 -1.691 100.108
27 41.182 3.232 .421 .006 -.005 53.968 .187 .351 .370 .092 .468 .591 .060 .180 -1.451 99.653
28 40.897 3.409 .430 -.032 .070 53.897 .187 .351 .370 .092 .468 .591 .060 .180 -1.527 99.443
29 40.300 3.403 .423 .033 -.006 53.974 .187 .351 .370 .092 .468 .591 .060 .180 -1.523 98.904
AVER: 40.856 3.461 .425 .001 .020 53.984 .187 .351 .370 .092 .468 .591 .060 .180 -1.548 99.497
SDEV: .330 .274 .008 .030 .026 .105 .000 .000 .000 .000 .000 .000 .000 .000 .114 .388
SERR: .117 .097 .003 .010 .009 .037 .000 .000 .000 .000 .000 .000 .000 .000 .040
%RSD: .81 7.92 2.00 2774.99 128.99 .19 .00 .00 .00 .00 .00 .00 .00 .00 -7.36
PUBL: 40.881 3.530 .373 n.a. .054 54.020 .187 .351 .370 .092 .468 .591 .060 .180 .005 101.259
%VAR: -.06 -1.96 13.87 --- -62.98 -.07 .00 .00 .00 .00 .00 .00 .00 .00-28754.95
DIFF: -.025 -.069 .052 --- -.034 -.036 .000 .000 .000 .000 .000 .000 .000 .000 -1.553
STDS: 211 206 211 42 39 211 0 0 0 0 0 0 0 0 0
(https://dl.dropboxusercontent.com/s/ll3hi53sg9uvf4w/TDI%20DurAp%208%20Lines.jpg?dl=0)
The scatter is difficult to work with so I tend to get 7-10 analyses and disable several of them. Here is another try with more analyses removed. The F composition is more reasonable. If I also remove lines 21 and 27, F comes out to 3.35 wt%.
St 60 Set 1 Apatite (Fluor) Durango, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO Na2O SiO2 SO3 As2O3 La2O3 Ce2O3 Pr2O3 Nd2O3 O SUM
21 41.098 3.102 .441 .017 .042 53.983 .187 .351 .370 .092 .468 .591 .060 .180 -1.400 99.582
23 40.862 3.298 .429 .023 .012 54.027 .187 .351 .370 .092 .468 .591 .060 .180 -1.480 99.469
27 41.182 3.232 .421 .006 -.005 53.968 .187 .351 .370 .092 .468 .591 .060 .180 -1.451 99.653
28 40.897 3.409 .430 -.032 .070 53.897 .187 .351 .370 .092 .468 .591 .060 .180 -1.527 99.443
AVER: 41.010 3.260 .430 .003 .030 53.969 .187 .351 .370 .092 .468 .591 .060 .180 -1.465 99.537
SDEV: .155 .128 .008 .025 .033 .054 .000 .000 .000 .000 .000 .000 .000 .000 .053 .098
SERR: .078 .064 .004 .012 .017 .027 .000 .000 .000 .000 .000 .000 .000 .000 .027
%RSD: .38 3.93 1.92 722.05 112.26 .10 .00 .00 .00 .00 .00 .00 .00 .00 -3.62
PUBL: 40.881 3.530 .373 n.a. .054 54.020 .187 .351 .370 .092 .468 .591 .060 .180 .005 101.259
%VAR: .32 -7.64 15.38 --- -45.07 -.10 .00 .00 .00 .00 .00 .00 .00 .00-27215.08
DIFF: .129 -.270 .057 --- -.024 -.052 .000 .000 .000 .000 .000 .000 .000 .000 -1.470
STDS: 211 206 211 42 39 211 0 0 0 0 0 0 0 0 0
(https://dl.dropboxusercontent.com/s/ordr7dyrtdm9z2z/TDI%20DurAp%204%20Lines.jpg?dl=0)
Here is the log-linear fit.
St 60 Set 1 Apatite (Fluor) Durango, Results in Oxide Weight Percents
ELEM: P2O5 F Cl MnO FeO CaO Na2O SiO2 SO3 As2O3 La2O3 Ce2O3 Pr2O3 Nd2O3 O SUM
21 41.103 3.445 .441 .017 .042 53.977 .187 .351 .370 .092 .468 .591 .060 .180 -1.545 99.779
23 40.863 3.404 .429 .023 .012 54.025 .187 .351 .370 .092 .468 .591 .060 .180 -1.525 99.530
27 41.186 3.504 .421 .006 -.005 53.962 .187 .351 .370 .092 .468 .591 .060 .180 -1.565 99.808
28 40.899 3.509 .430 -.032 .070 53.895 .187 .351 .370 .092 .468 .591 .060 .180 -1.569 99.501
AVER: 41.013 3.466 .430 .003 .030 53.965 .187 .351 .370 .092 .468 .591 .060 .180 -1.551 99.654
SDEV: .157 .050 .008 .025 .033 .054 .000 .000 .000 .000 .000 .000 .000 .000 .020 .162
SERR: .078 .025 .004 .012 .017 .027 .000 .000 .000 .000 .000 .000 .000 .000 .010
%RSD: .38 1.45 1.92 722.17 112.27 .10 .00 .00 .00 .00 .00 .00 .00 .00 -1.32
PUBL: 40.881 3.530 .373 n.a. .054 54.020 .187 .351 .370 .092 .468 .591 .060 .180 .005 101.259
%VAR: .32 -1.83 15.38 --- -45.07 -.10 .00 .00 .00 .00 .00 .00 .00 .00-28814.16
DIFF: .132 -.064 .057 --- -.024 -.056 .000 .000 .000 .000 .000 .000 .000 .000 -1.556
STDS: 211 206 211 42 39 211 0 0 0 0 0 0 0 0 0
(https://dl.dropboxusercontent.com/s/y7rcbjlmaqn6dpu/TDI%20DurAp%204%20Lines%20Linear.jpg?dl=0)
As I stated in my previous post, we now use our Durango as a secondary standard. Ca, P, and Cl tend to come out well most of the time, but F is variable, partly due to TDI fits, but heterogeneity is probably a factor, and our standard could use a new polish too.
Edited by John to make output results use a fixed width font (see the Tt button)
Quote from: EricKelly on May 06, 2015, 10:42:08 AM
Hi Brian,
How appropriate that you responded – you were my TA at Davis!
Hi Eric,
I was wondering if you were the same Eric Kelly. Good to hear from you.
By the way, since your F Ka peak is near 85 mm, then you are using LDE1, and the 2d is roughly 60 angstroms.
Brian
Quote from: Marc Schrier on May 05, 2015, 07:05:42 PM
Two papers I saw were: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638812/ and http://journal.chemistrycentral.com/content/7/1/56 Are you guys familiar with chlorapatite prepared in this fashion? -Marc
I have made an attempt using Klemme et al method, and you can readily produce mm sized crystals. Obviously, the crystal in the paper is the absolute best one they made, so ours did not look quite so nice.