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April 2007

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Subject:
From:
Paul Carpenter <[log in to unmask]>
Reply To:
JEOL-Focused Probe Users List <[log in to unmask]>
Date:
Wed, 4 Apr 2007 12:22:30 -0500
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*

This is an interesting system, with significant absorption of Al Ka by Ni
and the existence of characteristic fluorescence of Ni Ka by Pt La.  The
system also exhibits significant continuum fluorescence of both Ni Ka and Pt
La.  Here is output from the GMR thin film program for NiPt as a bulk
sample:
 
 GMR Electron Probe Bulk Microanalysis        File:FI070404.L06     4-Apr- 7
 ===========================================================================
 
 Analysis # 1 at 20kV;   Pouchou,Pichoir's Scanning (1990) Model;   iter.= 0

 Continuum Correction Included
 
 Elements :  Ni;Ka , Pt;La1

 
 
          Composition        K-ratio        Fchar    Fcont
        Weight%  Atom%   Cmp.Std. Pure El.    %        %
        =======  =====   =======  =======   ======   =====
 Ni :    23.13   50.00   -------  0.30315     4.04    5.58
 Pt :    76.87   50.00   -------  0.69171     0.00   -1.39
 sum:   100.00
 
There is continuum fluorescence observed for the pure element standards and
for the sample, with higher cf in the sample.  Result is overestimation of
Ni and Pt, with greater overestimation of Ni relative to Pt.  There is an
excellent example of this system as a ~1um Pt film on Ni substrate which is
presented in Pouchou and Pichoir's paper on the PAP correction in the green
book.  At voltages low enough to generate x-rays only in the overlying Pt
film, there is significant excitation of Ni in the substrate due entirely to
continuum fluorescence.  It is an excellent demonstration of the need to
address that effect -- we use it as a prime example in the Lehigh Advanced
Quant course.
 
For research grade analysis in this Al-Ni-Pt system it would really be
necessary to have a Ni-Al and Ni-Pt set of standards to handle the
absorption and fluorescence issues.  Multiple KV analysis should be used.
 
Cheers,
 
Paul
 
Paul Carpenter
Washington University
Campus Box 1169
1 Brookings Drive
Saint Louis, MO 63130-4862
 


  _____  

From: JEOL-Focused Probe Users List [mailto:[log in to unmask]] On
Behalf Of John J. Donovan
Sent: Wednesday, April 04, 2007 11:42 AM
To: [log in to unmask]
Subject: Re: [PROBE-USERS] Ni-Pt-Al standard?


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* Hi Ellery,
Some calculations are below for both Pt La and Pt Ma. There is a significant
absorption correction for Al so lower voltages will help somewhat there (so
long as you can still excite Ni Ka!). Ni is slightly fluoresced, obviously
by Pt. I'm just guessing on your composition, but clearly smaller amounts of
Al will experience a larger absorption correction.

Pt La
 ELEMENT K-VALUE ELEMWT% OXIDWT% ATOMIC% KILOVOL
   Ni ka  .35142  33.000   -----  28.762    15.0
   Pt la  .23560  33.000   -----   8.656    15.0
   Al ka  .22780  33.000   -----  62.583    15.0
   TOTAL:         99.000   ----- 100.000

 ELEMENT  ABSCOR  FLUCOR  ZEDCOR  ZAFCOR STP-POW BKS-COR  F(CHI)
   Ni ka  1.0141   .9836   .9415   .9390   .9344  1.0076   .9745
   Pt la   .9957  1.0000  1.4067  1.4007  1.4784   .9515   .9794
   Al ka  1.6431   .9989   .8826  1.4486   .7720  1.1432   .5400

Pt Ma
 ELEMENT K-VALUE ELEMWT% OXIDWT% ATOMIC% KILOVOL
   Ni ka  .35142  33.000   -----  28.762    15.0
   Pt ma  .25120  33.000   -----   8.656    15.0
   Al ka  .22780  33.000   -----  62.583    15.0
   TOTAL:         99.000   ----- 100.000

 ELEMENT  ABSCOR  FLUCOR  ZEDCOR  ZAFCOR STP-POW BKS-COR  F(CHI)
   Ni ka  1.0141   .9836   .9415   .9390   .9344  1.0076   .9745
   Pt ma  1.1085  1.0000  1.1851  1.3137  1.5208   .7792   .6286
   Al ka  1.6431   .9989   .8826  1.4486   .7720  1.1432   .5400


There is also of course the 5th order overlap of Ni Ka V on Al Ka to worry
about...
For Al ka      TAP at  8.35835 angstroms, concentration of   33.000 wt.% 
  Interference by Ni KA1      V     at  8.29130 =      9.2%
  Interference by Ni KA2      V     at  8.30970 =      6.2%

So long as your metals are freshly polished, pure metals should be fine. At
least accuracy of your standards won't be in question!

Note that because the relatively large Al absorption this system is of some
interest, a number of AlNi single crystals were grown to study this. I got
mine from GE (Eric Lifshin). This would be an excellent secondary standard
if you can get it.
john

At 09:00 AM 4/4/2007, Ellery Frahm wrote:



I have a post-doc researcher here in one of our engineering departments who
is interested in analyzing a Ni-Pt-Al system.  I've been trying pure metals
as standards for his samples, but obviously I'd like to minimize any
absorption or fluorescence issues there might be.  Does anyone have any
experience with such a system?  Do you know of suitable standards for such a
system, or have you just used pure metals?

John J. Donovan                                   [log in to unmask]
University of Oregon                             (541) 346-4632 (office)
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