Author Topic: Analysis of Boron  (Read 7242 times)

Probeman

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Analysis of Boron
« on: April 28, 2014, 12:24:26 pm »
I'd like to start a discussion of analyzing for boron using EPMA.

Of course, much of what we know from characterization of other light elements (O, N, C) also applies to boron, though usually without the contamination or native oxide issues! On the other hand, the absorption corrections for boron Ka are enormous, with absorption coefficients often as large as 10^5 cm2/ug.

In addition there can be large interferences from some other elements, particularly mid-z transition elements such as Mo.

To start things off I've attached a pdf of a paper just published on carbon doping of these magnesium borides and also a separate white paper on the details of the area peak factor (APF) shape corrections we utilized for previous work on the precursor magnesium borides, MgB2 and MgB4.

I'd be interested in seeing other efforts to quantify boron and what difficulties were encountered...
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Jeremy Wykes

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Re: Analysis of Boron
« Reply #1 on: April 28, 2014, 09:57:14 pm »
What is the best approach to analysing  low amounts (1000s ppm to several weight percent) B in silicate glasses where there is an overlap with the 3rd order Ka1 oxygen peak?
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Probeman

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Re: Analysis of Boron
« Reply #2 on: April 29, 2014, 01:50:11 pm »
What is the best approach to analysing  low amounts (1000s ppm to several weight percent) B in silicate glasses where there is an overlap with the 3rd order Ka1 oxygen peak?

Hi Jeremy,
I know you don't have my software, but I assume you've tried the PeakSight interference correction and it didn't perform well enough?

I wonder if the PFE quantitative interference correction would do a better job?

http://probesoftware.com/smf/index.php?topic=69.0

Do you have a good test standard for this situation?

Or have you tried a blank correction, assuming you can obtain a suitable blank standard?

http://probesoftware.com/smf/index.php?topic=204.0
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Owen Neill

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Re: Analysis of Boron
« Reply #3 on: April 30, 2014, 01:10:46 pm »
Jeremy - I've been after a similar problem, and would be interested to hear your thoughts. After running some wavescans (attached here) with an LDEB crystal (D=148A) on samples with different levels of B, there seems to be reasonable separation between the O and B peaks. In the wavescan on the B-free sample (2nd graph), the peak position is just off the edge of what I would call that O-peak. So I had been kind of ignoring it, but I suppose it wouldn't take much more O to cause some overlap. And given how low the B count rates are, just a little variation can make a big difference in calculated concentration.

How have you been doing your interference correction? The next thing I'd like to try is running in differential PHA mode, although my baseline scans have looked pretty ratty so far (low count rates again), so setting the window may be a challenge. Measuring O directly for an interference correction (maybe the 2nd order O Ka on the LDEB?) or using an LDE6 for B both sound less than optimal.

Anyway, would be interested to hear your (and the group's) thoughts on this.

For whatever it's worth, neither Raudsepp (1996) or Bastin and Heijligers (1991) mention the O interference, just the overlap with the Cl Li and Ln.
« Last Edit: April 30, 2014, 03:27:13 pm by Owen Neill »

John Donovan

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Re: Analysis of Boron
« Reply #4 on: May 01, 2014, 09:57:02 am »
How have you been doing your interference correction? The next thing I'd like to try is running in differential PHA mode, although my baseline scans have looked pretty ratty so far (low count rates again), so setting the window may be a challenge. Measuring O directly for an interference correction (maybe the 2nd order O Ka on the LDEB?) or using an LDE6 for B both sound less than optimal.

I would at least try measuring both oxygen and boron on a test sample and see how well the quant interference correction works. It often will surprise you... please try it and let us know what you find.
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Jeremy Wykes

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Re: Analysis of Boron
« Reply #5 on: May 01, 2014, 10:20:58 pm »
I grabbed some danburite (CaB2Si2O8) out of the museum a while ago--I will get back to this after I have submitted.

Edit by John: Yes, a nice crystal of that should be a good test. Is it very beam sensitive do you think? 

You might want to check this post that has attached a pdf of a paper NIST published a few years ago on analyzing boron on a beam sensitive hydrated material:

http://probesoftware.com/smf/index.php?topic=61.0.msg229#msg229

The other thing that should be mentioned is that it is especially important, with these low energy interferences, to make sure the interference correction is matrix corrected because the unknown and the standard used for the matrix correction, by definition, have to be different compositions!
« Last Edit: May 02, 2014, 01:12:07 pm by John Donovan »
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Spratt NHM

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Re: Analysis of Boron
« Reply #6 on: July 08, 2014, 04:02:15 am »
I have a copy of:
 
"Quantitative Electron probe Microanalysis of Boron in Binary Borides"

the details below may be of use for those trying to obtain this from libraries.

Bastin G.F. and Heijligers H.J.M.
University of Technology Eindhoven
Laboratory for Physical Chemistry
P.O. Box 513, 5600 MB Eindhoven
The Netherlands
ISBN 90-6819-006-7 CIP
SISO 542 UDC 541.1

March 1st 1986

This is a study (128 pages) with analytical data from 24 binary borides (does not include Mg Borides). Has a table of Mass Absorption Coefficients For B ka X-rays from a number of sources (Henke (74) and (82) but also includes a column labelled "present work".
Hope this is of help.

John Donovan

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Re: Analysis of Boron
« Reply #7 on: July 08, 2014, 10:14:55 am »
This is very interesting. The Henke MACs from 1985 (unpublished) are what I use in the LINEMU.DAT table, but I would be very interested in getting a copy of this.  Can it be scanned as a pdf?
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Jeremy Wykes

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Re: Analysis of Boron
« Reply #8 on: July 08, 2014, 08:30:28 pm »
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Spratt NHM

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Re: Analysis of Boron
« Reply #9 on: July 11, 2014, 07:37:09 am »
Hopefully I have attached a bmp of the MAC table from the first edition, which differs from the second.

John

John Donovan

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Re: Analysis of Boron
« Reply #10 on: July 11, 2014, 09:26:47 am »
Hopefully I have attached a bmp of the MAC table from the first edition, which differs from the second.
This is what I have in my Help file for boron, however, the empirical MACs table included with our CalcZAF distribution is attached below.

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D.

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Re: Analysis of Boron
« Reply #11 on: August 20, 2018, 01:27:23 am »
Does anyone have an LDE2 on a JEOL, 140mm rowland circle, and a tourmaline standard? If so, could you please do a wavescan from 180 to 205mm at 10kV, 10nA, 50um step, 200ms dwell? I'm having trouble picking out the B peak in what a users says is a tourmaline (I can see it clearly in my BN std). My xtal hasn't been checked for reference quality by the service engineer in many years...I'm curious to see how my spectrum and intensity compares to yours. I'm only getting 30cps via LDE2 on BN.

Thanks,
Deon.
« Last Edit: August 20, 2018, 01:31:19 am by D. »

Probeman

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Re: Analysis of Boron
« Reply #12 on: August 20, 2018, 08:09:02 am »
Hi Deon,
One problem is that B Ka is very heavily absorbed by Si:
john

"Table of MACs (mass absorption coefficients) from C:\ProgramData\Probe Software\Probe for EPMA\LINEMU.DAT"
"Emitting Element: B "
Absorber         ka      
      H     1723.04                                                          
      He   10694.59                                                          
      Li   31412.30                                                          
      Be   60146.45                                                          
      B     3333.97                                                          
      C     6337.93                                                          
      N    11196.24                                                          
      O    16431.25                                                          
      F    23306.02                                                          
      Ne   35353.24                                                          
      Na   43812.10                                                          
      Mg   59524.69                                                          
      Al   64297.13                                                          
      Si   83890.06                                                          
      P    68960.19                                                          
      S    74033.98                                                          
      Cl    7535.20                                                          
      Ar    9334.41
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Brian Joy

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Re: Analysis of Boron
« Reply #13 on: August 20, 2018, 08:25:51 am »
Hi Deon,
One problem is that B Ka is very heavily absorbed by Si:
john

Another problem is that a typical tourmaline only contains about 3.2 wt% B, while stoichiometric BN contains 43.56 wt% B.  I'm about to collect a wavelength scan using LDE2 under the stated conditions on a tourmaline that I analyzed last Thursday.  By stoichiometry it contains about 10.3 wt% B2O3.
Brian Joy
Queen's University
Kingston, Ontario
JEOL JXA-8230

Brian Joy

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Re: Analysis of Boron
« Reply #14 on: August 20, 2018, 08:57:35 am »
Hi Deon,
One problem is that B Ka is very heavily absorbed by Si:
john

Another problem is that a typical tourmaline only contains about 3.2 wt% B, while stoichiometric BN contains 43.56 wt% B.  I'm about to collect a wavelength scan using LDE2 under the stated conditions on a tourmaline that I analyzed last Thursday.  By stoichiometry it contains about 10.3 wt% B2O3.

Here are two scans collected using LDE2 under the stated conditions on the same tourmaline grain.  A further complication is that B Kα occurs at high Bragg angle on LDE2.  L ≈ 190 mm corresponds to sine(θ) around 0.68.



Brian Joy
Queen's University
Kingston, Ontario
JEOL JXA-8230