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posted by cmn32480 on Sunday November 06 2016, @08:23AM   Printer-friendly
from the watch-out-for-killer-rabbits dept.

nextBIGfuture is reporting on the creation of Solid Metallic Hydrogen (SMH).

Let that sink in for a moment.

Hydrogen is the lightest of all the chemical elements. We've heard of liquid hydrogen which, when combined with liquid oxygen, makes for some powerful rockets (think Saturn V). According to Wikipedia: "To exist as a liquid, H2 must be cooled below hydrogen's critical point of 33 K. However, for hydrogen to be in a fully liquid state without boiling at atmospheric pressure, it needs to be cooled to 20.28 K[3] (−423.17 °F/−252.87 °C)"

Now some Harvard researchers have gone one step further and, for the first time ever reported, have created solid hydrogen! Not only that, they have confirmed that it is metallic; thus: Solid Metallic Hydrogen is now a reality!

From the article:

* they have made some metallic hydrogen and have it in a cryostat in liquid nitrogen
* they might leave it under pressure and let it warm to room temperature or they could keep it cold and release the pressure
* they are planning to test for high temperature superconductivity

If it stays a metal at room temperature and after releasing pressure and was also a superconductor then it would be the holy grail of physics.

Controlled nuclear fusion, production of metallic hydrogen, and high temperature superconductivity have been listed as the top three key problems of physics. These problems all involve hydrogen and its isotopes.

Early theoretical predictions of metallic hydrogen being created at a pressure of 25 GPa (100GPa=1megabar) was way off. Modern quantum Monte-Carlo methods, as well as density functional theory (DFT), predict a pressure of ~400 to 500 GPa for the transition. The most likely space group for the atomic lattice is I41/amd. Metallic hydrogen has been predicted to be a high temperature superconductor, first by Ashcroft, with critical temperatures possibly higher than room temperature. Moreover, SMH is predicted to be metastable so that it may exist at room temperature when the pressure is released. If so, and superconducting, it could have an important impact on mankind's energy problems and would revolutionize rocketry as a powerful rocket propellant.

From the full report on arXiv.org (pdf):

We have studied solid hydrogen under pressure at low temperatures. With increasing pressure we observe changes in the sample, going from transparent, to black, to a reflective metal, the latter studied at a pressure of 495 GPa. We have measured the reflectance as a function of wavelength in the visible spectrum finding values as high as 0.90 from the metallic hydrogen. We have fit the reflectance using a Drude free electron model to determine the plasma frequency of 30.1 eV at T= 5.5 K, with a corresponding electron carrier density of 6.7x1023 particles/cm3, consistent with theoretical estimates. The properties are those of a metal. Solid metallic hydrogen has been produced in the laboratory.

The report also contains images of the sample as it underwent increasing pressures — revealing changes in appearance and behavior. There are also phase diagrams showing possible pathways from SMH at low temps and high pressures to SMH at room temperature and pressure. If realized, it would totally revolutionize rocket engines, among other possibilities.


Original Submission

[Continues...]

 
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  • (Score: 0) by Anonymous Coward on Sunday November 06 2016, @09:41AM

    by Anonymous Coward on Sunday November 06 2016, @09:41AM (#423066)

    If this turns out to be metastable, does it mean there might be a hydrogen fuel cell/battery hybrid on the horizon? Or a new kind of battery at least? Hydogen/carbon electrodes?

  • (Score: 5, Interesting) by VLM on Sunday November 06 2016, @01:10PM

    by VLM (445) Subscriber Badge on Sunday November 06 2016, @01:10PM (#423088)

    Sadly I don't think anyone thinks it will be stable at room temp and pressure other than sci fi authors and journalists. It should be stable at room temperature under immense continuous pressure.

    There are some practical modeling reasons such that if it were stable then there's enough galactic sources of pressure and "stuff" that we'd have discovered the stuff in rocks and things. Now that would be invalid IF the half life were short enough, but some would still sift down in meteors and things. Of course that would be invalid argument IF the stuff was none the less rare enough, not finding significant quantities of emeralds in meteors does not prove emeralds do not exist.

    Something I didn't get from the PDF, at least in a quick read, is why it took so long. DAC have been around since the 70s in fact I remember reading some high pressure research in the 80s where the Americans were trash talking the Russians because the Russians were actually getting funded so they were blowing millions on some crazy industrial press style technology whereas the Americans had relatively speaking no funding so our grad students were building diamond cells that cost nothing and fit in the palm of a rather strong hand and outperform the Russian multi-million ruble giant dinosaurs that filled entire warehouses. With the usual does of "rah rah amerika" BS.

    At this moment I'm having trouble thinking of what you could do with something thats tiny and superconductive at room temp. Thats kind of the problem of a DAC inherently the active area and volume is ridiculously small.

    Something missed in the article is currently, (err, at least in the 80s papers I remember) was all optical and the diamonds were all jewelry quality if not better. Flaws in the diamond make it shatter under pressure and anything other than perfect transparency has to be corrected in the results. So these are quality gems not cheap industrial trash. If you could do something useful with cheap industrial trash this would be a fun project for home machine shop people, DAC are precision objects but so are miniature gas engines and turbines and all that kind of stuff. If you want to do this at home you need two multi carat top quality diamonds and not care when they shatter. When I read the 80s papers a long time ago I fooled with the idea of using cheap synthetic sapphire and liquifying chlorine at room temp or maybe butane, which is not quite the level of heroic effort a DAC can do. Alas, is in the infinite pile of "things to do when I have time"

    Something that bugs me now that I'm old is no one has commercialized anything high pressure. "High pressure" by the standards of chem-E still tops out at a couple dozen atmospheres. Back in the old days 70s/80s high pressure research papers assumed that by the 90s we'd be taking advantage of the weird catalytic effects of a billion PSI or whatever to synthesize weird new plastics or antibiotics or some sort of exotic WTF-ium and unfortunately that whole region of technology seems scientifically interesting while completely barren of all engineering uses. The journalist and sci fi author types never caught on to it, but it seemed obvious at the time that unimaginably strange or cheap ochem products were naturally right around the corner relying on this new high pressure science stuff, but nothing ever happened.

    Relying on the above paragraph I can partially answer my own question that IF the whole field were not dead to chem-eng people, THEN maybe vast arrays of DAC would manufacture cellulosic ethanol or some damn thing one milligram (microgram?) at a time by relying on the catalytic effects of metalic hydrogen or something like that. But the field being dead means no chem-eng people have any ideas I'm aware of beyond the generic "wouldn't it be a good sci fi plot if...."

    • (Score: 2) by HiThere on Sunday November 06 2016, @06:40PM

      by HiThere (866) Subscriber Badge on Sunday November 06 2016, @06:40PM (#423208) Journal

      But what if it were superconducting and stable (with a half-life of a few thousand years) at room pressure and above liquid nitrogen temperature?

      That wouldn't show up in "the usual suspects", but would still be quite important. Of course, in that case the conditions in which it became explosively unstable would be extremely important. Some people seem to be ignoring that it's only predicted to be metastable.

      --
      Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
      • (Score: 2) by VLM on Sunday November 06 2016, @07:31PM

        by VLM (445) Subscriber Badge on Sunday November 06 2016, @07:31PM (#423224)

        with a half-life of a few thousand years

        Hmm yeah it would be interesting to model how short it would have to be, to not have enough to be noticed drift in from space. Admittedly see my example of the emeralds.

        • (Score: 2) by HiThere on Monday November 07 2016, @07:23PM

          by HiThere (866) Subscriber Badge on Monday November 07 2016, @07:23PM (#423700) Journal

          Well, you need to factor in that meteors often heat up markedly while entering, and that might itself destabilize it. So it's not really clear, though I have a hard time thinking of something that requires that much cold and pressure to make being very stable.

          --
          Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
    • (Score: 2) by sgleysti on Monday November 07 2016, @01:17AM

      by sgleysti (56) Subscriber Badge on Monday November 07 2016, @01:17AM (#423331)

      Check out page 3, paragraph 2. They used synthetic diamonds, cut off some of the surface to remove defects, vacuum annealed them, and then deposited a thin layer of alumina to preclude hydrogen diffusion. They also had to avoid exposing the diamonds to certain kinds of light under pressure, as this can cause failure. Lot of factors to take into account...

  • (Score: 1, Funny) by Anonymous Coward on Sunday November 06 2016, @07:01PM

    by Anonymous Coward on Sunday November 06 2016, @07:01PM (#423216)
    Probably a new type of bomb ;).