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I have to anneal a ceramic in high oxygen pressure, in an autoclave. For this purpose I need a chemical which can release oxygen at temperature less than or at 200 °C. Would appreciate any suggestion.

I am aware of $\ce{KClO3},$ but it seems that it releases $\ce{O2}$ at 300 °C.

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    $\begingroup$ Steel can do what you ask. Specifically a steel container with liquid oxygen inside it. $\endgroup$ Sep 2 at 8:31
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    $\begingroup$ KClO3 decomposition can be catalyzed by MnO2, but not sure how it goes down with T. You may be already aware of it. $\endgroup$
    – Poutnik
    Sep 2 at 8:51
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    $\begingroup$ Hydrogen peroxide solution, with any convenient catalyst, e.g., manganese dioxide. $\endgroup$
    – Ed V
    Sep 2 at 11:23
  • $\begingroup$ With MnO2, can KclO3 decompose below 200 C? Any reference for it. Thanks. $\endgroup$
    – user49535
    Sep 2 at 11:30
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    $\begingroup$ I have to anneal a ceramic in high oxygen pressure, in an autoclave. Need a source of oxygen for this purpose. Oxygen/weight is not so critical. Thanks $\endgroup$
    – user49535
    Sep 2 at 12:17
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Some ideas, looking around at some potassium salts:

  • Potassium permanganate, $\ce{KMnO4}$: decomposes at 240°C, probably the most readily available as I commonly see it in chemical laboratories.

  • Potassium manganate, $\ce{K2MnO4}$: decomposes at 190°C. Tends to disproportionate with water, but can be made from the permanganate plus concentrated potassium hydroxide solution.

  • Potassium ferrate, $\ce{K2FeO4}$: decomposes at 198°C. Breaks down readily in the presence of water. Listed as "Danger" is the GHS safety classification.

All such compounds should be handled with care and especially avoiding contact with organic material which they may cause to combust.

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    $\begingroup$ Thanks. I am wondering, when KMnO4 decomposes at 240 C, K2MnO4 is a byproduct. Does it also decompose further to liberate more oxygen? I have not found yet the chemical reaction of decomposition of K2MnO4 at 190 C. $\endgroup$
    – user49535
    Sep 2 at 13:51
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    $\begingroup$ The K2MnO4 would decompose further according to its WP article, but it gives no more details. A combination of K2O, MnO2, and lower potassium-manganese oxysalts plus evolved O2 would be a plausible outcone. One advantage of using transition metal oxysalts like these is they have no potential to form volatile compounds apart from O2. $\endgroup$ Sep 2 at 14:05
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    $\begingroup$ Wikipedia reports the existence of lower manganese oxyanions, so likely these are formed with additional evolution of O2. $\endgroup$ Sep 2 at 14:11
  • $\begingroup$ @user49535 You can check some papers: pubs.rsc.org/en/content/articlelanding/1971/j1/j19710001821 ... link.springer.com/article/10.1007/BF02549317. In short, $\ce{KMnO4}$ decomposition at 250-300°C is noted ($\ce{10 KMnO4→2.65 K2MnO4 + [2.35 K2O_{7.35},MnO_{2.05}] + 6O2}$, the bracketed part being $\ce{δ-MnO2}$). At higher temperature, $\ce{K2MnO4}$ decompose to form lower potassium-manganese oxysalts: $\ce{K4Mn7O16, K3MnO4, K3(MnO4)2}$. You can also check the kinetics or the reaction: sciencedirect.com/science/article/abs/pii/0040603185854794 $\endgroup$ Sep 3 at 2:53

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