Producing a desired crystal structure requires control over the conditions through which a sample is compressed and heated. Krishna Choudhary and Lester Nare discuss the multistage press used in the hexagonal-diamond experiment and how experimental design can influence the transformation pathway.
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31:00looking for. >> Yes. >> That are not necessarily naturally occurring. >> Yes, exactly. The reason why naturally occurring diamond is always naturally occurring that cubic diamond is because it's not a controlled process in the Earth's crust, right? So, it's just easy for the carbon to settle into the natural cubic diamond. But if we really want to go for this hexagonal thing, it's got to be real tight and real specific. And perhaps that's why the meteorite was showing these cases, right? Because like I mean, the scenario is crazy. It's a space rock coming at like it's very high speed, tens of kilometers per second, slamming into rock, right? This is a very key like scenario. >> Yes.
31:40>> That makes sense. >> So, so with that in mind, let's try to figure out how are we going to do this, right? How are we going to manufacture our hexagonal diamond and not cubic diamond? They use something called a Kawai type large volume press. So, this was conceptualized by Professor Naoto Kawai. It's a uniaxial hydraulic press with six steel anvils that are inward. Here's the key idea here. There's multiple stages. There's the inner stage, then there's the second stage anvil, and then there's an outer stage anvil. What I'm going to do is press. And when I press, the intermediate stage is going to press from all directions.
32:20Okay? So, it's not just going to give me this kind of force. It's going to give me an all direction type of force. And then that all direction type of force is going to press on a even smaller thing that is going to then let me control how >> Mhm. >> and in what direction and how much I am able to put pressure. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can
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