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This is an interesting result. It makes me wonder if you could grow a silicon ingot in this way. If so it would cut the cost of silicon solar cells significantl

This is an interesting result. It makes me wonder if you could grow a silicon ingot in this way. If so it would cut the cost of silicon solar cells significantly (a big chunk of their cost is the cost of the ingot, the ingot cost is a function of time to produce, producing them quickly would get more ingots per unit time from a given reactor). Another crystal structure that would be useful would be sapphire for things like sapphire screens and other covers.

dilawar 3y ago
One of the authors on LinkedIn definately thinks so. Looks like more papers are coming https://www.linkedin.com/posts/wenhao-sun-20383b7b_ten-years-ago-as-a-phd-student-i-became-activity-7133871765046403072-zbaS?utm_source=share&utm_medium=member_desktop https://www.linkedin.com/posts/wenhao-sun-20383b7b_ten-years....
kergonath 3y ago
> This is an interesting result. It makes me wonder if you could grow a silicon ingot in this way. No really. The way we grow silicon crystals is already very efficient and would not be improved by this sort of thing. We grow them by pulling a seed (in carefully controlled conditions, with a bit of twisting and other tweaks, but still), adding dissolutions steps would waste a lot of time. Besides, the defects they get rid of by dissolution (say, a magnesium atom on a calcium site, which we call antisite defects) do not exist in silicon, in which all atoms are identical. > Another crystal structure that would be useful would be sapphire for things like sapphire screens and other covers. Again, sapphire is something that is quite easy to grow. And like for silicon, it does not have any antisite defects. One of the limitations with growing sapphire is its purity, and it would not be improved by additional dissolution steps. I am not saying that similar steps could not be used to help produce industrially relevant crystals, just that silicon and sapphire are very unlikely to be examples of that. This is a way to grow in a lab in weeks a crystal that would take millions of years to grow in nature. It would not really help with crystals that grow already very efficiently, and whose growth is controlled by other mechanisms.
- kragen 3y ago
  additional dissolution steps could definitely improve purity; i mean that's basically how zone melting does it
  - kergonath 3y ago
    That’s melting, not dissolution. They came nowhere near the melting point of dolomite in the paper, AFAICT.
    - kragen 3y ago
      i admit to being pretty ignorant about thermochemistry is there a relevant difference between crystals approaching equilibrium with a melt and crystals approaching equilibrium with a solution? because i had the impression that the mechanisms were the same and the line between these processes was actually a little bit fuzzy, what with things like hydrate crystals and aquo complexes (i think you can't melt dolomite tho, at least near atmospheric pressure)
- cyberax 3y ago
  > The way we grow silicon crystals is already very efficient and would not be improved by this sort of thing. We grow them by pulling a seed One interesting remaining unsolved problem is highly homogenous doping. Such silicon is needed for very high-current and high-voltage switching (like invertors on large wind turbines or HVDC power lines). Creating it is so hard that we have to use FREAKING NUKES. Seriously, a chunk of pure silicon is irradiated by neutrons in a reactor, transmuting some silicon atoms into phosphorus. It's apparently the only way to do it, which has always seemed wild to me.
  - orbital-decay 3y ago
    That ought to be a first-class candidate for space manufacturing. (high quality microgravity)
ganzuul 3y ago
Gallium nitride perhaps.
- wenhaosun 3y ago
  Good guess! Yes we are working on GaN next in ammonothermal growth.

dilawar 3y ago

One of the authors on LinkedIn definately thinks so. Looks like more papers are coming https://www.linkedin.com/posts/wenhao-sun-20383b7b_ten-years-ago-as-a-phd-student-i-became-activity-7133871765046403072-zbaS?utm_source=share&utm_medium=member_desktop https://www.linkedin.com/posts/wenhao-sun-20383b7b_ten-years....

kergonath 3y ago

> This is an interesting result. It makes me wonder if you could grow a silicon ingot in this way. No really. The way we grow silicon crystals is already very efficient and would not be improved by this sort of thing. We grow them by pulling a seed (in carefully controlled conditions, with a bit of twisting and other tweaks, but still), adding dissolutions steps would waste a lot of time. Besides, the defects they get rid of by dissolution (say, a magnesium atom on a calcium site, which we call antisite defects) do not exist in silicon, in which all atoms are identical. > Another crystal structure that would be useful would be sapphire for things like sapphire screens and other covers. Again, sapphire is something that is quite easy to grow. And like for silicon, it does not have any antisite defects. One of the limitations with growing sapphire is its purity, and it would not be improved by additional dissolution steps. I am not saying that similar steps could not be used to help produce industrially relevant crystals, just that silicon and sapphire are very unlikely to be examples of that. This is a way to grow in a lab in weeks a crystal that would take millions of years to grow in nature. It would not really help with crystals that grow already very efficiently, and whose growth is controlled by other mechanisms.

kragen 3y ago
additional dissolution steps could definitely improve purity; i mean that's basically how zone melting does it
- kergonath 3y ago
  That’s melting, not dissolution. They came nowhere near the melting point of dolomite in the paper, AFAICT.
  - kragen 3y ago
    i admit to being pretty ignorant about thermochemistry is there a relevant difference between crystals approaching equilibrium with a melt and crystals approaching equilibrium with a solution? because i had the impression that the mechanisms were the same and the line between these processes was actually a little bit fuzzy, what with things like hydrate crystals and aquo complexes (i think you can't melt dolomite tho, at least near atmospheric pressure)
cyberax 3y ago
> The way we grow silicon crystals is already very efficient and would not be improved by this sort of thing. We grow them by pulling a seed One interesting remaining unsolved problem is highly homogenous doping. Such silicon is needed for very high-current and high-voltage switching (like invertors on large wind turbines or HVDC power lines). Creating it is so hard that we have to use FREAKING NUKES. Seriously, a chunk of pure silicon is irradiated by neutrons in a reactor, transmuting some silicon atoms into phosphorus. It's apparently the only way to do it, which has always seemed wild to me.
- orbital-decay 3y ago
  That ought to be a first-class candidate for space manufacturing. (high quality microgravity)

ganzuul 3y ago

Gallium nitride perhaps.

wenhaosun 3y ago
Good guess! Yes we are working on GaN next in ammonothermal growth.