Author Topic: Indetermination Fe, Cu,... in simple stoichiometric oxide  (Read 336 times)

Rom

  • Professor
  • ****
  • Posts: 60
Indetermination Fe, Cu,... in simple stoichiometric oxide
« on: January 16, 2022, 08:45:49 PM »
Hi dear colleagues,
Our issue is indetermination on 0.5-1wt.% metals (Fe, Cu,...) in simple stoichiometric oxides if we use standards pure metals.
We didn't find peak shifts when come from metals to oxides.
K-line, Lif.
To simplify our task we use specify (not measured) oxygen concentration.
What direction should we look? These are strong lines and use APF or MAC corrections looks unusual.
Thank you.

Probeman

  • Emeritus
  • *****
  • Posts: 2430
  • Never sleeps...
    • John Donovan
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #1 on: January 17, 2022, 09:49:18 AM »
Our issue is indetermination on 0.5-1wt.% metals (Fe, Cu,...) in simple stoichiometric oxides if we use standards pure metals.
We didn't find peak shifts when come from metals to oxides.
K-line, Lif.
To simplify our task we use specify (not measured) oxygen concentration.
What direction should we look? These are strong lines and use APF or MAC corrections looks unusual.

1. Please explain "indetermination".

2. One should not observe peak shifts with high energy emission lines (e.g., Fe Ka, Ni Ka, etc.). Peak shifts due to chemical states are usually only seen when the transition shell is also the bonding shell (e.g., C Ka, N Ka, Si Ka etc.).

3. Either pure metal (if unoxidized) or oxide primary standards should be fine as the most important correction is the background correction at low concentrations:

4. Please explain "What direction should we look? These are strong lines and use APF or MAC corrections looks unusual."

5. Here are some additional readings for you:

https://probesoftware.com/smf/index.php?topic=1404.0

https://probesoftware.com/smf/index.php?topic=1378.0
The only stupid question is the one not asked!

Rom

  • Professor
  • ****
  • Posts: 60
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #2 on: January 17, 2022, 04:17:53 PM »
1.Indetermination: the measured concentration of metal in oxide is lower in 0.5-1 wt% its stoichiometric (real) concentration.
2. Yes
3. Yes
4. I just kindly asked where should I looking for my mistake (because 2,3 - yes).
5. Thank you

Probeman

  • Emeritus
  • *****
  • Posts: 2430
  • Never sleeps...
    • John Donovan
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #3 on: January 17, 2022, 04:57:19 PM »
1.Indetermination: the measured concentration of metal in oxide is lower in 0.5-1 wt% its stoichiometric (real) concentration.

Did you mean to say: "the measured concentration of metal in oxide is lower than 0.5-1 wt% which is its stoichiometric (real) concentration."?
The only stupid question is the one not asked!

Rom

  • Professor
  • ****
  • Posts: 60
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #4 on: January 17, 2022, 07:36:20 PM »
Yes. You are right.

Probeman

  • Emeritus
  • *****
  • Posts: 2430
  • Never sleeps...
    • John Donovan
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #5 on: January 17, 2022, 09:27:58 PM »
For minor elements of first row transition elements I wouldn't be too worried about MACs (certainly not APFs), but did you perform careful wavescans to check the background positions?  That's going to have the biggest effect on accuracy for minor elements.

Also are the totals good?  Did you include oxygen from ferric iron in the calculation?

https://probesoftware.com/smf/index.php?topic=92.msg8593#msg8593

What is the oxide matrix?  What are the minor elements in question?
The only stupid question is the one not asked!

Rom

  • Professor
  • ****
  • Posts: 60
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #6 on: January 17, 2022, 11:36:06 PM »
I didn't understand about minor elements. I told about metal measure in pure oxides, which are very close to stoichiometric compound (Fe2O3, Cu2O etc.)

Yes, I performed careful wavescans to check the peak shifts and background positions.

Totals are 98.5-99.5. I used both: measured or specify (not measured) oxygen concentration.

My issue is absolutely the same question of your topic! Thank you!
But my results didn't change if I use "calculate excess oxygen from Ferrous/Ferric ratio" checkbox (attached file). In excel file I see zeroes in FeO, Fe2O3, excess oxygen etc. columns.



 
« Last Edit: January 18, 2022, 12:32:27 AM by Rom »

Rom

  • Professor
  • ****
  • Posts: 60
Re: Indetermination Fe, Cu,... in simple stoichiometric oxide
« Reply #7 on: January 19, 2022, 02:48:47 AM »
There are 3 questions:
1. What I should check If I want to use "calculate excess oxygen from Ferrous/Ferric ratio" - how can I start this options;
2. How I can start this options for system Cu-O or Sn-O etc., without Fe (it is necessary if we research  alloys after quenchingfrom liquid  for instance).
3. What is the fundamental base of  "the measured concentration of metal in oxide is lower than 0.5-1 wt% which is its stoichiometric (real) concentration"? Everything is clear if we discuss Oxygen concentration but why this correction affects on metal concentration?
Thank you a lot.