Standards Which Should Be Developed For EPMA

[John Donovan]

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?

[Marc Schrier]

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

[John Donovan]

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://probesoftware.com/smf/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.

[Brian Joy]

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.

[John Donovan]

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

[John Donovan]

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

[John Donovan]

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

[Brian Joy]

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).

 

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).

[John Donovan]

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):



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://probesoftware.com/smf/index.php?topic=701.msg4268#msg4268

[Brian Joy]

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.

[John Donovan]

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

[Brian Joy]

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.

[Marc Schrier]

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

[John Donovan]

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

[Probeman]

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://probesoftware.com/smf/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!