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Nitrogen Semiconductors

Posted by timothy on from the one-day-one-day dept.

wearedan writes: "I came across an article on how nitrogen acts as a semiconductor when under very high pressures.The really interesting bit is that the formed solid can be stable even when returned to ordinary atmospheric pressures."

10 comments

  1. Ferris by tomzyk · · Score: 1

    "Pardon my French, but Cameron is so tight, that if you stuck a lump of liquid nitrogen up his ass, in two weeks, you'd have a semiconductor."
    -Ferris Bueller (if the movie was created a few years from now)

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  2. 2.4 million atmospheres? by zorba1 · · Score: 1

    Anyone know what they used to achieve such high levels of atmospheric pressure?

    1. Re:2.4 million atmospheres? by Christopher+Thomas · · Score: 3

      Anyone know what they used to achieve such high levels of atmospheric pressure?

      For the metallic hydrogen experiments I read about a while back, they used a "diamond anvil cell". This is a fairly small device that uses a screw to close a pair of lever arms. The compression cell at the base of the lever squeezes the sample between two diamonds. A metal gasket surrounds the cell.

      The nice thing about this is that the diamonds pass a wide range of light frequencies, which lets you measure material properties optically.

      The group that I was reading about almost, but didn't quite, succeed in making metallic hydrogen.

      I have no idea whether the nitrogen semiconductor group used this apparatus or something else. I suppose that if you were clever enough to find a fast way to take the measurements, you could just set off a bomb on top of the sample and measure for a few microseconds. Pressure is difficult to control, but if you can measure pressure accurately while you do this, you can simply plot your data with pressure as one of the axes.

      Some types of industrial diamond are made using explosives.

    2. Re:2.4 million atmospheres? by Yazeran · · Score: 1
      I have no idea whether the nitrogen semiconductor group used this apparatus or something else. I suppose that if you were clever enough to find a fast way to take the measurements, you could just set off a bomb on top of the sample and measure for a few microseconds. Pressure is difficult to control, but if you can measure pressure accurately while you do this, you can simply plot your data with pressure as one of the axes

      This is exactly what is beeing done in nuclear testings and similar (non nuclear) experiments.

      Real artificial diamonds for cutting tools can be made this way (and are as far as i know as it is an inexpensive method)

      Yours Yazeran

      Plan: To go to Mars one day with a hammer.

  3. Is this safe? by squeegee-me · · Score: 1

    Just wondering, when it returns to normal preasure levels, they apparenlty have this new substance remaining after it forms at high preassure. Is there any chance of it returning to a gasous form and hence exploding to it's original volume?

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    1. Re:Is this safe? by Christopher+Thomas · · Score: 3

      Just wondering, when it returns to normal preasure levels, they apparenlty have this new substance remaining after it forms at high preassure. Is there any chance of it returning to a gasous form and hence exploding to it's original volume?

      Sure. Just heat it. It's both more entropically favourable and more energetically favourable for it to be a gas (above nitrogen's freezing point, at least), so as soon as you get over the activation energy, *boom*.

      According to the article, the sample at 1 atm had to be cooled quite a bit to be stable. For all I know, they could have taken it down below nitrogen's freezing point, which would just make this an interesting allotrope of frozen nitrogen.

      Material properties should change as pressure is varied, as the energy bands within the material will shift. This would be very interesting to measure experimentally to check our models of materials at high pressures (and you can bet your socks they've submitted a funding application already to do this).

    2. Re:Is this safe? by The_Dougster · · Score: 1
      Wow, I can see the headlines:

      House Explodes - Man overclocks computer!

      I think that solid nitrogen might make a great explosive, not so sure about semiconductors.

      Hey, we found that TNT is a semiconductor! Lets hook these wires up and test it out!

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    3. Re:Is this safe? by CowbertPrime · · Score: 2

      actualy it depends on the electron stabilization.
      If you pressed the nitrogen tightly enough, you might form resonance structures and associated structures that allow electron delocalization. Remeber in N2, there are 2 unshared pairs of electrons, and it's triple bonded, so one of the pi bonds will be weaker than the sigma bond and the other pi bond.

      I know in organic chemistry, there are compounds which have N2 as a substituent in a ring, and due to electron delocalization, these compounds are pretty stable and you can crystallize them.

    4. Re:Is this safe? by Christopher+Thomas · · Score: 2

      actualy it depends on the electron stabilization. If you pressed the nitrogen tightly enough, you might form resonance structures and associated structures that allow electron delocalization.

      Perhaps I gave the wrong impression in my previous post. I'm not saying that a solid allotrope of nitrogen couldn't exist at room temperature - just that it would be *more* stable in gaseous form, and would thus tend to revert to this form when sufficiently provoked.

      It's easy to demonstrate that the gaseous form is the most stable under standard conditions - if it wasn't, the atmosphere wouldn't contain gaseous nitrogen. It's had plenty of time to be converted to an alternate form by whatever mechanisms are appropriate.

      As the solid nitrogen would tend to revent to its gaseous form when provoked, and as gaseous nitrogen doesn't like being stored at solid densities, you'd almost certainly get an explosive release of stored energy if you heated or otherwise sufficiently agitated a sample of solid nitrogen.

      Interesting argument, though. In your opinion, is there any chance at all of an allotrope of solid _hydrogen_ being stable much above hydrogen's freezing point, or would this not work with just a "1S" shell?

  4. Rocket fuel by Anonymous Coward · · Score: 2

    Article says this implies that the same might work to create solid metallic hydrogen at normal pressures. If so, it would be an extremely high-energy rocket fuel. An earlier experiment with metallic hydrogen is described in this article, which mentions the rocket-fuel possibility.