Full thermal decomposition of metal oxides?

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Discussion Overview

The discussion centers on the thermal decomposition of metal oxides, specifically focusing on the decomposition of Fe3O4 into its base elements, iron and oxygen. Participants explore the temperatures required for significant decomposition and the methodologies for determining these temperatures based on bond energies and structures. The context includes theoretical and practical applications in metal production where traditional reducers are insufficient.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the temperature at which Fe3O4 decomposes mostly into its base elements and seeks methods for determining this based on bond energies and structures.
  • Another participant suggests using Ellingham diagrams to find temperature-oxygen partial pressure regimes for metal oxides, noting that iron oxides are well-studied.
  • A later reply expresses uncertainty about the applicability of Ellingham diagrams for iron oxides, indicating a need for further investigation.
  • Links to relevant Ellingham diagrams and research papers are provided, emphasizing that decomposition depends on both temperature and oxygen partial pressure.

Areas of Agreement / Disagreement

Participants generally agree on the utility of Ellingham diagrams for understanding the decomposition of iron oxides, but there remains uncertainty regarding their specific applicability and the temperature ranges involved. The discussion does not reach a consensus on the exact temperature for significant decomposition of Fe3O4.

Contextual Notes

Limitations include the dependence on specific bond energies and structures, as well as the unresolved nature of the temperature and oxygen partial pressure relationship in the context of thermal decomposition.

hellfire2
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I haven't been able to find much information on the thermal decomposition of metal oxides into their corresponding metals and oxygen. What temperature would Fe3O4 decompose mostly(80%) into its base elements? Additionally, how can this information be determined based upon bond energies/structures for other elements?
For those who are curious, I am looking into methods for producing metals thermally for use where reducers such as carbon are not present in high enough concentrations to be useful.
Thanks!
 
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Check Ellingham diagrams. They provide temperature-oxygen partial pressured regimes for metal oxides. Iron oxides are well-studied. So surely you will find the needed data.

Direct computations, requires full electronic structure calculations coupled with finite temperature effects. I think there was a paper in Phys. Rev. B journal on this calculation for iron oxide. I can try googling it if you are interested.
 
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Whoops misclicked there. Yeah if you could point me in the right direction for those I would appreciate it. I did look at some of the Ellingham diagrams before but was not too sure about the iron oxides because they seem to run off most of the charts. I will further investigate the paper as well.
 
This Ellingham diagram contains all the decompositions of iron oxides starting from Fe2O3 through Fe3O4, FeO, and eventually to Fe.

http://web.mit.edu/2.813/www/readings/Ellingham_diagrams.pdf

The paper I mentioned cared more about the transitions in the PO2-PH2O space with little regard to temperature, but it may still be useful:
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.83.094112

An arxiv version of the paper is here:
https://arxiv.org/pdf/1101.3105.pdfThe key thing is that the decomposition depends on both temperature and oxygen partial pressure. I hope this helps.
 
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Useful nucleus said:
This Ellingham diagram contains all the decompositions of iron oxides starting from Fe2O3 through Fe3O4, FeO, and eventually to Fe.

http://web.mit.edu/2.813/www/readings/Ellingham_diagrams.pdf

The paper I mentioned cared more about the transitions in the PO2-PH2O space with little regard to temperature, but it may still be useful:
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.83.094112

An arxiv version of the paper is here:
https://arxiv.org/pdf/1101.3105.pdfThe key thing is that the decomposition depends on both temperature and oxygen partial pressure. I hope this helps.
Thank you very much for this! This helps a bunch!
 

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