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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Ales on February 06, 2018, 03:25:22 PM

Title: Analysis of brown contamination on the glass surface
Post by: Ales on February 06, 2018, 03:25:22 PM
Hello, do you have any idea about the origin of brown contamination that is located on the coated part of my experimental glass.
I consider about furnace contamination, but I am not sure (84% of Zn, Sn).

Brown contamination on the surface of the glass - SEM EDX:

Mon Sep 18 12:47:59 2017

Filter Fit    Chi-squared value:  9.434 

Correction Method:  Proza (Phi-Rho-Z)

Acc.Voltage: 15.0 kV  Take Off Angle: 31.5 deg

 

Element    Element    Atom %    Compnd     Norm.   

   Wt.%        Formula    Compnd   

  C         ---         ---        CO2         ---   

  O      23.81S      57.69             ---   

  Mg         ---         ---        MgO         ---   

  Al       1.09       1.56      Al2O3       2.06   

  Si       1.81       2.50       SiO2       3.88   

  S       1.15       1.40        SO3       2.88   

  Ca       2.52       2.44        CaO       3.52   

  Fe       2.43       1.69      Fe2O3       3.47   

  Zn      40.41      23.96        ZnO      50.30   

  Ag       0.57       0.20       Ag2O       0.61   

  Sn      26.20       8.56       SnO2      33.27   

----------    ----------        ----------   

Do you have any suggestions?
I would appreciate any help.
Thanks,
Mystique
Title: Re: Analysis of brown contamination on the glass surface
Post by: marquis on February 09, 2018, 07:28:45 PM
My first guess is a heavy metal sulfide.  From the list you gave, tin sulfide would be my first guess.

I'm used to stand alone edxrf, not the sem xrf.  Can you increase the voltage on your unit to detect more elements?  Maybe there is another element present.

Good luck