Analysis of Boron

[Probeman]

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...

[Jeremy Wykes]

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?

[Probeman]

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

[John Donovan]

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.

[Jeremy Wykes]

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!

[Spratt NHM]

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]

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?

[Jeremy Wykes]

You can find the Bastin & Heijligers PDFs here:

http://alexandria.tue.nl/repository/books/304562.pdf

http://alexandria.tue.nl/repository/freearticles/620800.pdf

[Spratt NHM]

Hopefully I have attached a bmp of the MAC table from the first edition, which differs from the second.

John

[John Donovan]

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.

[D.]

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.

[Probeman]

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

[Brian Joy]

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]

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.

[D.]

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.

Thank you Brian, I appreciate it!

I attach my presumably-tourmaline raw and smoothed scans. The KLM database puts the peak at about 191 as you can see, while the BN (not attached) is peaking at about 193.X .

So what do you guys think....is that small bump at 191 is the B peak in tourmaline? And what is the big peak at about 195...is that a shifted B? O-III?

Deon.