I'm researching possible materials that maybe be used in the far future. I came across something called metallic oxygen. If oxygen is compressed to 10GPa, it turns into a dark red solid O8. If this is compressed further to 96GPa, it undergoes another phase transition and becomes metallic.

Right now it can only exist under the ridiculous pressure, but given today's knowledge of chemistry and material science, is there some possible way to make this material stable at atmospheric pressure, while still being mostly metallic oxygen, not just some oxide? Perhaps a mix with other high pressure allotropes that chemically hold each other together or cancel out each other's energy, forming a sort of a stability well?

My knowledge of materials science is not that great, so I don't even know if my question makes physical sense, but hopefully someone can get this and help me out.

Edit: making my question more precise. I don't expect the metallic oxygen to be stable in pure form. What I think I'm looking for is some kind of alloy based on metallic oxygen that would be stable at lower pressures. It's not important what it's mixed with as long as it keeps the density and structure of metallic oxygen. I want to know if this idea makes sense scientifically, if it's at least theoretically possible to have such an alloy.

  • $\begingroup$ We don't know, most likely not the way you describe it. One can explain the issues with it, consider the chemistry s.e. though, chemistry answers here are always, let's say sloppy. However, I want to point out something: transparent aluminium, star trek material. Perfectly accepted, makes no sense, the name is the only description and explanation offered basically. If you want to invent the stuff you make up in fiction first, you are not a world builder but, well, an inventor. Better focus on a great story for example and say it works. $\endgroup$ – Raditz_35 Jun 22 '18 at 8:21
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    $\begingroup$ This might be one of the rare, truly scientific examples of the mythical "force-field". Ionised oxygen is compressed using a strong EM field in a vacuum to produce ionised metallic oxygen, which remains stuck in place on the anode. Advantage: when the power is cut off, the oxygen reverts to gas and disperses. Disadvantage: it probably won't survive outside a vacuum, and the power considerations would make it prohibitively expensive for anything useful $\endgroup$ – nzaman Jun 22 '18 at 8:54
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    $\begingroup$ but given today's knowledge of chemistry and material science, is there some possible way to make this material stable at atmospheric pressure No, they would have done it if that was possible. $\endgroup$ – Jan Doggen Jun 22 '18 at 8:57
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    $\begingroup$ @raditz_35 I have held transparent aluminum in my hands. Amazing stuff. Lightweight but bulletproof. They make it in Dallas. Yes, the inventors were inspired by Star Trek. :-) $\endgroup$ – SRM Jun 22 '18 at 9:58
  • $\begingroup$ @SRM I want to point out that if you are referring to ALON, then transparent aluminum is just a nick name and not really an accurate description - just to avoid confusion $\endgroup$ – Raditz_35 Jun 22 '18 at 10:02

The metallic state of oxygen would last only as long as there'd be a monstrous pressure keeping it that way. Even the most compat and solid water ice will not stay that way if artificially created in an incompatible environment -aka: You can make ice cubes in Dubai, but you can't keep them in the sun for long.

And the conditions for metallic oxygen are so exotic as not to find anyplace on or under Earth to maintain stability

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    $\begingroup$ Yes if it's pure, but it can be mixed with something to change the required energy. like adding antifreeze lowers water's freezing temperature or salt lowers its boiling temperature. I'm looking for a similar effect, just... significantly... larger. $\endgroup$ – Curiosity Jun 22 '18 at 10:56
  • $\begingroup$ @Curiosity then you don't have metallic oxygen anymore. I have one example of a metal alloy using oxygen, but it isn't what you want. en.wikipedia.org/wiki/Gum_metal $\endgroup$ – T. Sar Jun 22 '18 at 13:24
  • $\begingroup$ So there isn't any way to combine metallic oxygen with something else while keeping its crystal structure and general properties? Gum metal looks cool, but it's only got 1% oxygen, it's mostly titanium. I'm fine with it not being pure metallic oxygen, I'm not expecting it to be, but I'm thinking an alloy that is still mostly metallic oxygen, like over 50%, and keeps its density and structure as metallic oxygen. I could just come up with any random set of elements or not specify them if I can't find an answer, but I'm just trying to see if this approach sounds theoretically plausible at least. $\endgroup$ – Curiosity Jun 22 '18 at 13:54

The stable existence of any substance is driven by its Gibbs free energy, as compared with that of other possible substances: the one with the lowest Gibbs free energy exists, the others are less stable and turn into the more stable. I.e. liquid water Gibbs free energy is lower than that of ice above 0 C at 1 atm, therefore ice melts above that temperature.

As you state, metallic Oxygen forms only at ridiculously high pressures. We can translate that as "only at those pressures the Gibbs free energy of metallic Oxygen is lower than normal Oxygen".

This is something with which we cannot really fiddle: it's a consequence of physics and chemistry laws, and unless we are so lucky to have some substance which is metastable (like diamond, which is not the lowest Gibbs free energy configuration at standard condition, but it is stable unless you warm it up, turning it into graphite), we have no way of having metallic Oxygen at our standard conditions.

  • $\begingroup$ I know that there isn't a known way to make it stable in its pure form, I was more thinking of creating an alloy or a chemical compound where the other element would provide the energy to make it stable or metastable. But still having the properties of metallic oxygen. Does that work at all? $\endgroup$ – Curiosity Jun 22 '18 at 10:54
  • $\begingroup$ @Curiosity, the conditions in which it exist do no allow experimenting with it. And I doubt an alloy would still be considered "metallic oxygen". $\endgroup$ – L.Dutch Jun 22 '18 at 10:58
  • $\begingroup$ It doesn't have to be called that. Like alloys of iron are called steel, but they are mostly iron, with other elements enhancing its properties. Like I've stated in the other comments, I'm not looking for the actual detailed explanation of how it would be done, that would require inventing it. I'm just looking for a way that would sound plausible or sort of follow the general rules of chemistry. It doesn't actually have to be right, no one will know until the far future. $\endgroup$ – Curiosity Jun 22 '18 at 11:19
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    $\begingroup$ @Curiosity, if you want to alloy oxygen with handwavium, you can, but I would not use the science based tag then $\endgroup$ – L.Dutch Jun 22 '18 at 11:21
  • $\begingroup$ I'll try to make my question more simple. Is a metallic oxygen alloy scientifically possible? Could it theoretically be stable at lower pressures? $\endgroup$ – Curiosity Jun 22 '18 at 11:51

Unlikely, because Oxygen is Too Reactive

It sounds to me like you're hoping that metalic oxygen will have a metastable form, acting metallic even after it is returned to room temperature. A real-world parallel would be diamond, which is a metastable form of carbon.

Unfortunately, diamond is able to retain its form because it has a stable crystalline matrix that ties up its available electrons. You need to provide a lot of energy to break up those carbon-carbon bonds, thereby allowing the diamond to break down into a lower-energy form, graphite.

A side effect of these carbon bonds is that diamond acts as an electrical insulator. Put simply, it doesn't have enough free electrons to conduct electricity.

Metals, however, are characterized by electrical conductivity, and I don't know if you could call something "metallic" if it was an insulator. Certainly when we talk about "metallic hydrogen" we do so because it becomes electrically conductive (with an associated increase in optical reflectivity).

Gaseous oxygen is a diatomic compound. If you could compress a large amount of oxygen into a metallic state, it would necessarily break down into single-atoms, thereby freeing up valence electrons so it can act like a metal. But all those free electrons will allow the oxygen to react with whatever it encounters, and chemical reactions with oxygen release a lot of energy.

I speculate that the first reactive compound which came into contact with your metastable metallic oxygen would combust explosively, triggering the nearby oxygen to revert to diatomic (gas) form as well. Even a single spec of dust could do that, or perhaps a cosmic ray.

If you have any doubts about the explosive reactions triggered by pure oxygen, read about the Apollo 1 launch pad fire, or the (ig)nobel prize awarded to George H. Goble for lighing a barbecue grill with liquid oxygen. Given the relative density of metals vs. gases, building anything from metallic oxygen would be asking for trouble, because you're just concentrating the reactants.

Since you asked about metal alloys, I don't see how they could possibly reduce the danger associated with room-temperature metallic oxygen while allowing it to remain metallic. Anything you alloy with the oxygen will want to form a compound with that oxygen, and give off a lot of energy when it does.

  • $\begingroup$ Ah, I hadn't thought of the reactivity. How do scientists manage to make it under high pressure without it burning up? I'd have thought the high pressure environment would make it even more reactive. What other material would you choose to make into a futuristic metal, that isn't usually a metal under normal conditions? $\endgroup$ – Curiosity Jun 23 '18 at 10:05

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