Harder Than Diamond? The New Hexagonal Diamond Breakthrough (EP 38)

0:00So imagine you've spent about 50 years arguing as a scientific community about whether a legendary material exists, and then finally someone has made it and they're holding it in their hands. We're talking about a material that in theory is harder than the hardest known material, which is conventional diamond. This, this, this is like, this is some beef, dude. Yeah, this is what beef looks like. Yeah. Like in the. Or something right? Hello Internet, this is your captain speaking, Lester Nare, joined as always by my Co host and our resident PhD Krishna Chowdhury. Today we're going to be diving into a paper that is actually a follow up to our episode 5 story on unbreakable hexagonal diamonds.

0:45This paper was published in Nature on March 4th of 2026 from three Chinese teams from Zhangzhou, Nanjing and Henan universities. As always, we're going to learn about the science from the ground up today on this follow up episode, because this is from First Principles. So imagine you've spent about 50 years arguing as a scientific community about whether a legendary material exists, and then finally someone has made it and they're holding it in their hand and you can see it with the naked eye.

1:33And that's roughly the situation when it comes to hexagonal diamond or lawns delight. It's a form of carbon that was first proposed in the 1960s, and material scientists have been seeking this Holy Grail ever since, OK? There's been debate about whether it even exists in the 1st place. OK, there's a new paper that's saying that they've actually made it, and the stakes are quite enormous because we're talking about a material that in theory is harder than the hardest known material, which is conventional diamond. This is an upgrade on diamonds that we normally have on our ring finger and things like that. The current benchmark for the hardest material is a conventional diamond, and here we've gone a step further. So it's a very big deal because in industry diamonds are applied all over the place, OK.

2:24It's not just used as jewelry. In fact, the the reason why a diamond is so expensive is because the Jewelers are artificially crunching the supply while the demand is really high because of all of Hollywood and pop culture and things like that. But diamond in its core is really effective in all sorts of industry. For example, diamond diamond tipped drill bits. They can board through rock for any type of stuff. Oil exploration, mining, anything diamond coated cutting tools. They can machine aerospace grade titanium. Titanium is a hard metal but if you've got a diamond coated saw you can cut through titanium.

3:07Diamond windows. They protect infrared sensors and military systems. And the other cool one that I hadn't really thought about was diamond heat sinks. So. Interesting. Diamond is a really good insulator and it's also a really good heat sink in the in the in the means that like it can extract heat out of its environment and dump it to something else. And those are being explored for next generation computer chips because silicon is sort of meeting its thermal limit when it comes to heat dissipation.

3:36This is why everyone is saying that, you know, the data centers up in space won't work is because silicon is really bad at dissipating heat, right? We have to have giant cooling systems in order to do that. Well, if you have a chip that has integrated silicon and diamond to manage that heat dissipation, you could now push even further right on how big you can make a server rack and things like that. And so we desperately need these types of materials.

4:03Diamond is one of these things. And imagine now you can make an upgraded diamond that's going to upgrade all of these in in industrial applications, right? And the other reason why this matters, this particular story, is because for the longest time, computational simulations, meaning I take the material, I take all of the atoms in the arrangements of that material. I put that into a computer, and I asked the computer to just churn Schrodinger's equations. And the what we know about physics and material physics, if we do that in computer simulation, those simulations suggest that this thing is real.

4:41But for the longest time we don't have any material samples to analyze. And so there's a fundamental problem now, because our physics of what a material should look like is saying one thing and we've never been able to do it. So it's almost like a bedrock foundational problem for the field, right? That theoretically this thing should be possible. Why is it so hard? And is it even possible, right? Because if if it's if it's truly not, then we have to go back to the drawing board on fundamental material science. And that is some a very uncomfortable scenario, right for everyone in the field.

5:17Right, right. Yes. And so the status now is we've got a team in China that synthesized millimeter sized pure hexagonal diamond and it's resolving this 50 year academic debate. This happened earlier as well in 2005. As you alluded to, we covered a story in. 25/20/2025. Yeah, 2025, sorry. We covered a story last year that purportedly made hexagonal diamond. This is another research team in China that is doing the same thing, maybe a bit better, and we'll get into some of the drama there because there's a lot of drama and it's quite hilarious.

5:51We got the tea, everybody. OK, so let's start from the basics. Yes, carbon. Carbon is the 6th element on the periodic table. It has 6 protons in its nucleus, usually 6 elect, 6 neutrons, usually 6 neutrons in its nucleus, sometimes 7, sometimes 8. But six protons in the nucleus mean you've got 6 electrons revolving around the atom. 2 are in the inner shell, but that means there's four that are left for that outer shell. And if there's four that are left for the outer shell, that means there's four holes.

6:24There's four valence positions where other electrons can come in. That is the maximum because the total number that you can have in that outer shell on that second ring is 8. So if you have three, that means you can have like 5 holes, but with four you can either give four or you can take 4. You can. So you can make the most bonds that way, right? Oxygen can only really make 2 bonds, the other ones can only make, you know, whatever is less. But 4 is right in the middle where I can give four or I can take 4 so I can make the most number of bonds.

6:58That's why it's so important in organic chemistry for life in general. The big thing is carbon is able to make bonds with itself, and sometimes it makes these things called allotropes. This is pure carbon. There is nothing other than carbon in these substances. For the longest time we thought there were only two graphite, which is the pencil lead. That's pure carbon, nothing else. And then there is obviously diamond, again pure carbon. Now, how do we know what the structure of the carbon in these materials is?

7:34Well, usually what we do is we do something called X-ray crystallography. This was a technique pioneered by William Henry Bragg and his son William Lawrence Bragg. We covered some of the drama there, the fact that William Lawrence Bragg, the son, did all of the math and did all of the actual groundwork. But William Henry Bragg, his father, published a paper about the technique and did not put his son's name on it. And that was a sticking point for his son Lawrence, who always wanted to be called by his middle name because that distinguished him from his father. William Lawrence Bragg and Henry Bragg, they both won the Nobel Prize in 1915, the only father, son duo to win the same Nobel Prize.

8:19And he was 25 at the time, the youngest Nobel Prize winner in the sciences. He went on to be the head of Cavendish Lab at Cambridge and managed the empire that was Cavendish Lab at Cambridge University. The idea is the following. You shoot X-rays out of crystal. The crystal is going to have a lattice structure, meaning all of the atoms are going to be arranged in a very nice regular fashion. Like we'll, we'll see some of the fashions that they're arranged, but in any case, it's like Lego blocks that are repetitive.

8:49And because they're repetitive, the X-rays are going to interfere at certain angles. And if I have a detector on the end, I can find spots where the X-ray is added up and other spots where the X-ray is canceled out. And using that pattern I can discern what is the structure of the crystal inside. OK, that's the whole game with X-ray crystallography. As a crude analogy is it's almost like making hand puppets with a light source on a wall and and you're looking at the shadow to determine what is the actual exactly figure. Yeah, that's basically it.

9:22But in like all three dimensions with like frequency and everything. Extremely more. Much more complex. Yeah. But at the end of the day, what you can do is through that, you can figure out what is the cubic, what is the structure of that crystal inside. And when we do this with diamond, we figure out that it's a cubic structure. This is what diamond looks like at the atomic scale. Each of these blue orbs is a carbon atom, and each carbon atom is attached to four other carbon atoms in this tetrahedral structure. That orange tetrahedron that is triangles on triangles, there's four triangles that are connected together. It's the first Platonic solid that is on our logo right here, and it's a beautiful structure.

10:08The reason why it's called a cubic diamond is notice that the repetitive fundamental unit of the crystal is in the shape of a cube, right? If you imagine you can take that same cube, put one right next to it, put one right next to it and stack and you get bigger and bigger. And a diamond is going to have, you know, 10 to the 20 of these carbon atoms or something like that. An enormous amount, but at the fundamental scale, that is what the diamond looks like. The reason why it's so hard is each of those bonds are highly tight covalent bonds where the carbon atoms are sharing an electron with the neighboring carbon atom. Remember I said carbons can do 4 bonds. All four bonds are other carbon atoms. This thing is extremely tightly packed. OK.

10:54And it's single bonds that are going in. Yes. OK, So that's the fundamental unit of stacking. It's a cube. Hence normal diamond is called a cubic diamond right now. In 1962, researchers predicted that there would be a possible hexagonal polymorph of the diamond. They went through the, this is, you know, 1960. So this is before computers and stuff, But you can literally sort of do the mathematics of Schrodinger's equation around a carbon atom. And you can make the argument that instead of this cubic structure, there could be a kind of hexagonal structure that is even more stable and even more hard. OK, the question is, is that real? Right.

11:41So 1962 they published this paper in Nature. And in the 1967 they came up with the Canyon Diablo meteorite. There were people who were analyzing A meteorite that fell in Arizona 50,000 years ago. If you've ever, ever been to the Grand Canyon, the South side, there is Meteor Crater right next to the Grand Canyon sort of exit on the 40 freeway. I was there when I was very young. It was one of the first sort of science field trips that my family took and I got to see the Meteor Crater in Arizona. It is an awesome, awesome place.

12:1650 meters is about the size of the meteorite that hit Arizona, and it has a bunch of shards that fell all over Arizona and that they've been recovered. OK. Now this meteor hit Arizona extremely fast and meteors are made a lot of out of carbon. There's a lot of carbon in meteors. When they hit the Earth at this incredible velocity with incredible pressure, there's incredible heat. Perhaps the carbon is going to form a weird allotrope. And so in 1967, a paper came out again in Nature Lawns Delight, a hexagonal polymorph of diamond.

13:00They're saying that they found that hexagonal polymorph that was suggested in theory five years ago, right? They named it Lawns Delight. And just a brief sort of digression into why Lonsdaleite, it's named after Dame Kathleen Lonsdale. She was a foundational X-ray crystallographer and Prison Reform advocate. Very, very cool person, OK? She pioneered the use of X-ray crystallography. She actually did her PhD under William Henry Bragg, the dad, OK.

13:33And she wanted to understand the structure of aromatic compounds. Specifically, she figured out that benzene, which is A6 carbon ring with six hydrogens, that thing is a flat ring. She figured out that the structure of that thing was flat. She's one of the first to actually use something called Fourier transforms, which is where you go from frequency space to position space. The real mathematics behind X-ray crystallography. She's the one first one to figure out how to quantitatively use the mathematical theory to understand even more complicated patterns with extra crystallography.

14:10Okay. And so she laid the foundations of, for example, later on when extra crystallography was being used for proteins and other kinds of really weird amorphous solids or DNA, the famous DNA picture that Rosalynn Franklin took of the extra crystallography with the X, Her theories are what laid the foundation for that kind of work to be like, what is the kind of molecule that would give me an X? Yep. And Francis Crick was the one who figured out, OK, it's got to be a spiral, right? Right.

14:38And the, the spacing of the DNA of the, the spacing of the dots on that photo tell you how far away nucleotides are in DNA and how far away the turn is on a Helix and things like that. So incredible individual. She's one of the 1st 2:00 first two women elected to the Royal Society. She was also a Quaker, which is like, you know, it's the religion that Benjamin Franklin is famous for in Pennsylvania and things like that. So she refused to register for civil defense duties during World War 2 because they're very non violent people, right? And she was in prison for a month. And her experience in that prison was like, she used that experience to become a passionate Prison Reform advocate, right?

15:20So. Yes. All over the place she was. Great scientific impact, great social impact, not only by being a pioneer as a woman at the time who were not allowed in these scientific spaces as a generalization, but also still being grounded to that the world is still a society and it's not just the work we do in a lab. Exactly. Yeah, so incredible woman. This paper that comes out of 1967 by Frondell and Marvin, they claimed to have found the hexagonal diamond.

15:54They named it after Dame Kathleen Lonsdale. They call it Lawns Delight. They did X-ray diffraction on this thing, and they showed that it has the same pattern as something called wurzite, which is a zinc sulfur mineral that has hexagonal symmetry. Here, what you're looking at is an animation of wurzite. Just imagine instead of the two different colors, which are zinc and sulfur, all of them are the same color because they're all carbon atoms. That's where all the carbon atoms would be.

16:20There's two things that are different about this compared to the cubic diamond. OK, yes, first thing obviously is look at the unit cell. It's a hexagonal prism. Yes, right. There's a hexagon face on the top and the bottom. And the other thing is you're actually packing the carbon atoms closer together because the tetrahedral, the tetrahedral surfaces are flat compared to in before they were sort of at an angle at that 104.5° angle. Here they're flat. You're packing more carbon atoms. The bond length in between these carbon atoms is smaller and so the hardness mechanism is because of the resistance to like any form of stress, right?

17:07This thing is going to be harder than cubic diamond. Yes, OK. And I have one just brief question on this visual, just because there's as a layman the other visual difference here. And I understand that we're looking at wart site in this example. And the key difference is there's sort of that bottom row, right? So you have the sort of all the tetrahedrals packed in the hexagonal prism at the top, Yeah. And then there's just like a bottom row of empty space that kind of closes it out.

17:36Yeah, well, that thing is just going to be repeating over and over. I think they're only showing. One segment. Yeah, exactly. But because it's a crystal, it's like going to just keep repeating. Makes sense? Just want to clarify. Yeah, no, that's a good question. Now, if we think about how this is different from cubic diamond, diamond at a grand scale, not just that, OK, the fundamental unit is hexagonal rather than cubic. Yes, that's the first thing.

18:00But now let's let's consider like packing a bunch of carbon atoms like spheres in a, in a enclosed space, OK, How do we do that? Well, there's two ways of doing it. On the left is your cubic diamond. OK. That's the the one that we had seen earlier where the tetrahedrals are in a cubic sort of repeating unit. Yes, when you do that, layers of carbon atoms repeat, but they repeat in a ABCABCABC kind of manner, meaning you're going to get one layer of carbon atoms. The B layer, which is on top is going to fit somewhere in the gaps of that.

18:40The C layer is going to fit somewhere on the gaps above that, but it's going to be slightly offset from the A layer. So I'm going to get 3 distinct layers and it'll repeat like that. Yep. OK with hexagonal diamond, just because the nature of the geometry, I only need 2 layers of stacking. It's going to be A, then B is going to fit exactly in the gaps. But because A is slightly different from the previous A, the next layer can just repeat the bottom layer.

19:07So my stacking is going to go A/B, A/B, A/B instead of ABCABCABC. Yes. And just for folks who may be listening, I just want to put a disclaimer. This is a slightly important episode for visual records points because it's it's very obvious visually. It's kind of hard to describe. It is just with audio or, or with voice. But I think sort of like what's interesting is you can kind of see the the offset you're talking about. Like imagine a staircase that has three stairs, one and then two. Like when you're looking at it from the side. Yeah.

19:41So you know, the cubic diamond is almost like 3 steps on the staircase. Yeah. Where the offset on the C is significantly farther away from the A Yeah. But in the hexagonal is just two steps. And so imagine you're creating like this staircase that's going back and forth. Yeah. Like this having 2 versus 3 you can already. Think you can already think? Yes. Structurally that it would be. It would be better, it would be harder. The things would be closer packed, right?

20:07The bonds would be a bit stronger, the layers would be a bit stronger, right? And just theoretically, you can just like kind of imagine that this hexagonal diamond is going to be harder and better than a cubic diamond, right? Right. Right, we will not be playing the Daft Punk song Harder Better Faster stronger. However, it would be a good theme for this episode. Yeah, yeah, yeah. We'll put it in the social right. So OK, discover in the 1960s, this is when they're like, okay, I think we found it right, yes.

20:32So in the 1960s, in parallel, it's kind of a golden age for high pressure physics because General Electric, GE, the company, they achieved the first reproducible synthesis of diamond from graphite, you know, lab diamonds, synthetic diamonds. They invented it in the 1960s. This is General Electric actually 1954. They use a kind of belt apparatus. It's it's effectively high pressure, high temperature. Yeah. OK. So you take graphite, you would subject it to 10 giga pascals, which is 100,000 times atmospheric pressure.

21:05You raise the temperature up to 1000° and you get diamond. This was a triumph in material science. Francis Bundy, Hall, Strong and Wentworth, they got enormous recognition. They they're in the Inventors Hall of Fame. Very controversially. No Nobel Prize for them. It might be because there's four people and the Nobel Prize can only go to three. But usually when that happens, you just wait for one of them to die, right? And then you give it to the other. 3. You know, but they didn't even do that, which I think is quite controversial because like lab grown diamonds are a game changer for all of these industrial applications that I was telling you about, right?

21:44So very much has changed the landscape of material science and industry. They probably should have gotten the Nobel Prize, but I think now all four of them have passed away. So it's too late. Understood. In any case, they've shown that we can make cubic diamond. And they this is also where we get the meme and the like colloquialism about strong as a diamond diamond under pressure. Like all of these various thingies, yes, is because the way you make diamonds is through. It's almost like, like almost most people kind of know. It's like heat.

22:14Yeah. And squeezing. Yeah. Diamond. Yeah, that's why it happens deep in the Earth's crust if it's natural. And here we're just trying to sort of replicate that natural mechanism, that's why. Yeah, exactly. Harder than a diamond. The diamond is forever stuff that's. Hollywood. That's Hollywood. That's. Hollywood and the Debeers Corporation. The as hard as a diamond. Diamond under pressure. That's physics. Right, right, right, right. Just to be clear.

22:36Yeah, just to. Be clear, there is a difference here in in how we approach things. So people start making lab grown diamonds and now we want to make lawns delight. We want to make hexagonal diamonds. We've made cubic diamonds. We still have not yet made the the thing we've already theoretically identified exactly. Possible. Yeah. Yeah. But there's a lot of problems. The samples are too small, the crystals are submicron in size, and there's no real definitive proof because you need a lot of a sample. And by a lot, I mean even like a millimeter worth of stuff to do anything, right?

23:10Right. So with all of this comes skepticism. It's like, well, why can't I just make right hexagonal diamond? How come every time I'm trying to make diamond, I always get cubic diamond, right? Which is the stuff that I see on Earth, right? And now you're telling me this, this meteor has it. But like, even the meteorite sample might not be that good. And that's where we come to 2014 Nature Communications. There's a paper lawns of the light is faulted and twinned cubic diamond and does not exist as a discrete material. What a banger of a title.

23:44Okay, it's just like, no, this is fake. For those who might not understand, this is like def the definition of a clap back. Yes, yeah. Like to put in the title, does not exist as a discrete material when for like the past 40-50 years people have been like talking about how this is a thing, right? And so here is the argument that he's making. He's saying that lawns of light is just cubic diamond, but with something called stacking faults. What he's saying is if you look at the meteorite samples, OK, there's a bunch of cubic diamond lattice structure, but that cubic diamond lattice structure is not contiguous.

24:21There's like cubic diamond here, and then there's another domain of cubic diamond over here. And the boundary between them is slightly offset. Yeah. So when I put this through X-ray diffraction, I am going to get artifacts that suggest that there are spots where there is hexagonal diamond. And he goes through and does transmission electron microscopy of the sample of that meteorite, the Canon Diablo meteorite. And he's showing that there are these stacking faults. There are these boundaries, right? And so if you have enough stacking faults in your cubic diamond, the diffraction pattern is going to resemble the hexagonal stuff.

24:57And so you're not actually making hexagonal diamond, you're just making a bunch of cubic diamond with defects. And then when you put it through the X-ray diffraction O, it's hexagonal. You can't say that. So he called it Fugazi, Yeah. He's like, he's like, no, this is, this is nothing. This is nothing, right? But meanwhile, computational studies are refusing to give up. And this is what I was talking about, right? Like you go, you go through and you and you and you put it in the computer and the computer's saying this is fine.

25:22This is totally a possible allotrope of carbon. This works. The carbon atoms are all happy. They don't want to go into another phase like if you set them up like this, they'll stay like. This based on the rules of of just foundational and basic physics that we understand to be true. You can extrapolate in a computer and it it's fine. Yeah, it's fine. It only works so. So what? What gives? Which means the theory of the case here is that it is an engineering problem, not a fundamental physics or science problem. That's kind of the what's been the argument. It's been the argument and but in order to prove that, you got to just solve the engineering problem. Yeah, right.

26:01And that requires a lot of fundamental physics at the end of the day. And so in 2024, we were at this interesting state, right? The theory says lawns and legs should be real. The experiment says, Nah, this is where we get into this paper. Bulk, hexagonal diamond, great name, three word. I haven't seen a shorter Nature paper title to be honest. Well done. Right. Well, bulk hexagonal diamond. That's it. That's it. That's it. No nature, no narrating.

26:33Yeah, no, just. This is what we this is what it is. Right, it's quite nice. It's. Quite nice. It's a, it's a macroscopic pure sample that they've created. OK, they're showing that it's not an artifact, and let's get into how exactly they did it. Yes, all right. And before we do. Yes. I'm going to do some brief show notes. So if you are listening to this and you were a listener on episode 5 when we talked about the other group of Chinese teams that did the story, you're this is going to be very exciting because all of the stuff we do here, much like science and science research itself, builds on top of each other.

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27:56If you think this is better than Netflix, you can make a monthly recurring donation, but every little bit helps. It is the two of us here who both produce, write, distribute and run the entire show and we really like to make sure it's at a high level, high quality overlays, great breakdowns, and your support is the key aspect that allows us to do so. And with that, let's get back into the story. Yep, bulk hexagonal diamond. How did they do it? How? Did they do it the?

28:24Challenge. Is the following actually OK? You know, let's ask why is it so easy now? I mean, it's hard, but why is it so easy to create cubic diamond, normal diamond, but it's so hard to create hexagonal diamond, right? We're just pressing graphite, but every single time we're just getting the lab grown standard diamond. I want to create hexagonal diamond. The reason why is that standard high pressure, high temperature conditions favor the formation of cubic diamond because cubic diamond is actually a global energy minimum. You know, when we think about energy landscapes, we can think about orientations and how different orientations of the diamond have different energies, Yes. And it turns out the cubic diamond, even though it's sort of bigger and has that ABCABC stacking, yes, that has a lower energy and is more favorable than this ABAB smaller configuration.

29:21Very interesting. So it's you got to go through a very specific route in order to get to this local minima and avoid the global minimum. That makes sense. OK, that's what it turns out. And that has a lot to do with a lot of the computational work that was done around the hexagonal diamond to figure out why is this? Why is this not working? Other people have done that work. OK, so this team is like, all right, how are we going to make oppress? How are we going to make an experimental apparatus that is going to avoid that global minimum, not create a normal diamond and create our hexagonal diamond?

29:58Is it almost like saying we intentionally have to create an experimental apparatus that is not optimizing for the easy? Like the best? Yes, yeah, Yeah. Like we're in tennis. Yeah, the easiest. We need to go and figure out some way to like go off off the, you know, right. Like it's like we got 2 depressions on a hill. It's like when you're skiing, right? Yeah. You don't want to go all the way down right to the, the chairlift. Yes. In Mammoth you sometimes you want to go to the outhouse in the back to get your grilled cheese safe.

30:30Right. But that requires being very cognizant of which turns you're taking down the ski hill, right? Otherwise you're just going to end up in the lodge like everyone else and then have to wait like 2 hours to go up the mountain. We've all been. There, yeah, we've all been there. But no, but that's actually a really. That's a really interesting insight, in that a suboptimal path can actually lead to the the derivative effects that we are looking for, yes, that are not necessarily naturally occurring. Yes, exactly.

31:05The 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 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, yes, it's a space rock coming at like it's very high speed, yes, 10s of kilometers per second, right, slamming into rock, right, right.

31:37This is a very key like scenario, yes. 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? Yes. They use something called a Kauai type large volume press. So this was conceptualized by Professor Naoto Kawaii. 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.

32:13What I want to do is press, and when I press, the intermediate stage is going to press from all directions. Okay, so it's not just going to give me this kind of force, it's gonna give me an all direction type of force, Yes. And then that all direction type of force is gonna press on an even smaller thing that is going to then let me control how and in what direction and how much I am able to put pressure. So that's my high pressure and then high temperature.

32:42I can just like make the thing hot from a variety of different mechanisms because. It seems the variable here that it needs to be modified is not the heat. But the pressure, and here's why. The pressure is what matters. But they actually started not with just normal graphite, but with a specific type of graphite called highly oriented pyrolytic graphite. This is a photo from their supplement. On the top is the normal graphite that you use in lead.

33:10In pencil lead graphite is a bunch of layers of carbon rings. Okay, it's layers on layers of carbon rings, but in naturally occurring graphite, the layers are kind of, you know, off each other. They're not completely flat. OK, what I want is exactly flat graphite, OK, not off where like some some carbon atoms are closer than other carbon atoms. I want exactly flat. So they created a high pressure environment and then a rapid cooling thing to make your amorphous graphite, so to speak, this very highly oriented pyrolytic graphite. Now what is the advantage there?

33:49The advantage there is that the graphite itself has ABAB memory. Oh, very. This is where it's going. Yeah. Yep, Yep, Yep, the. The cooking the the material that they're trying to cook with already has the geometry of their end product. Right, right. And and naturally occurring graphite is naturally imperfect and those imperfections lead to getting to lead to the destination of the, the global minima. But, and that's so interesting, but because we are now making sure that we're having a 5 Wagyu beef going in and not around the corner grocery store beef going in, we're going to get exactly what we want as the chef on the out. Exactly.

34:37And so this, you can already see the ABAB stacking, you can imagine the lower layer is B, the upper layer is A. And now I can just stack this on top of one another, right? And so now when I press on them, perhaps that geometry is going to be. Reserved. That makes sense. There's another problem though. Just because you start with ABAB graphite, right? It's going to be ABAB one on top of the other. If I push from all directions, that might cause the graphite to scrunch up, losing that symmetry.

35:06So I need to be able to only press from the top and bottom. OK, OK, Now in any type of press, that's very difficult. But what they did was they added a layer of aluminum on top and the bottom. And what that alumina does is not distribute any of the stress laterally just because of the way aluminum works. And all of the stress was in the up and down direction. So they had the press and on the press they layered aluminum on the top and the bottom so that when they were pressing, the stress was only in the vertical direction. OK.

35:41Once they do that, finally this is how it should work in theory. They did large scale molecular dynamic simulations. Here we've got layers on layers of that ABAB graphite and you can see a tiny defect is forming and as you press the orange is that hexagonal diamond, it rapidly forms, right? There's kind of a nucleation zone where the defect kind of starts and the layers of graphite are covalently bonding to one another. And then as you press more and more it rapidly sort of like like a like a contagion, right that that bond sort of spreads out.

36:17It propagates from this like initial inciting incident location. And this is so now understanding the the component parts, this makes a lot more sense in terms of you know, because normally what you would get in this use case is the spreading of cubic diamonds. But because we've created our specific type of graphite, because we've created the specific pressure mechanism, and we've coded it at the top and bottom to make sure the pressure was. Distributed only yeah.

36:50And as you can see, the the it's only being squished this way vertically, right? It's not being squished the other way, right, right. And so that those two dimensions this dimension and the one inside and out is being preserved. The only part that's getting squished is vertical. And that's why we're getting very specific hexagonal graphite, sorry, hexagonal diamond. Yes. And so this is the molecular dynamic simulation, right? That they where they show this is how we think it should happen, right. This is part of their paper.

37:14And obviously for this type of paper, you want to show the mechanism. OK, so this was a very cool molecular dynamic simulation that they're showing. So they do the experiment and they come up with samples. These are what the samples look like yes. You've got some pretty large samples. So that bar is 200 microns yes, five of those is a millimeter. So this is about the size of a millimeter plus, which means I can see it with my naked eye. Right Before, everything was like submicron, right level. Like I had to go into the Kenyan Diablo meteorite, go under a scanning tunneling microscope, and even then there was that dude who was like, no, this is just cubic diamond right here. The whole thing they're saying is hexagonal diamond, yes. OK, yes, and and the the, the, the idea being it, it both passes just like the kind of the sniff test because of its size. Like it's just like, Oh well, if you can't make it that big then it I don't care.

38:06But it then also makes it easier to look at it. Yeah, because now with something this big, I can actually start doing X-ray diffraction studies in a clean manner. I can do transmission electron microscopy in a clean manner. And so at first all they did was X-ray diffraction and this thing called selected area electron diffraction, which is just instead of X-rays, you're using electrons. And they did a Vickers hardness scale. On the left you're seeing the X-ray diffraction on the X axis is like an angle of like how the X-ray that's coming in is getting bumped out. And then on the Y axis, you're seeing like what the absorption rate is, right?

38:45Like the detector? Yes. And the little spots are where you're seeing the distances between atoms. And they're saying that this is key to showing that this is his hexagonal diamond. Yes. They also do the Vicar's hardness scale. Now I can read the peer review. OK, So what do you think? Right. The peer reviewers are gonna read this and I. Just want, I just want to note really briefly because you know, there is a little bit of a in the zeitgeist right now.

39:14There is a public debate about Chinese universities and the legitimacy of the work that they do. I'm saying this is what the Zeitgeist conversation is like in the US and this was published in Nature. Which is a Springer publication from the UK. So, you know, and they're, what's great, which you talked about this recently, is they're now putting the reviewer notes on these papers so you can get a little bit more of an insight into how the sausage was made to make a better characterization about your own perspective of the study.

39:51And so I'm just, I, I know that there's, I, I think there's been a little bit of poo pooping that's been undeserved and you can go just look. Yeah, and you can look and see what people are saying, right and. If we look at that peer review paper, so version zero, that's the one that they initially submit to the editor. The editor then deems, OK. I mean, if it's bulk hexagonal diamond, this does deserve getting published into Nature. So now I'm going to put it off and give it for review to the some of the top scientists in the field who know what they're talking about. OK, In this case, reviewer one comes back after version 0 and he says overall this paper should be rejected. Classic, classic.

40:31Usually it's reviewer 2, right? Because like reviewer 1 is like, cuz imagine you're like opening up your peer review file, right? And usually like reviewer 1 is like kind of nice about it. And then reviewer 2 is just going at it here. Like, I guess the editor didn't change the, you know, cuz the editor could have just like changed it doesn't matter who you wanted to is, right? But anyways, they open up the peer review file and imagine the 1st overall, this should be rejected. OK, so here's the complaint that reviewer #1 is making. He's saying that basically the X-ray diffraction and this electron diffraction, those two data sets are inconsistent. We don't know what the original version of the figures are, right?

41:13So we can't see. But apparently they were inconsistent and they didn't analyze different axes. Like you know, with with the with the crystal, there's like different directions that I can sort of probe. I can just rotate my sample on my X-ray diffraction apparatus and then I can probe different directions of the crystal. They didn't do that. That's I think that's fair. That's totally fair. They also didn't do this thing called right veld refinement, which is a way to computationally clean up diffraction data, which apparently like everyone does. So they didn't do that and they're using this is this one I thought was really hilarious.

41:46They're using diamond, cubic diamond, the normal diamond, to probe the hardness of this thing, and they're claiming that this thing is harder. That doesn't quite make any sense. Yeah, yeah. Yeah, right. You're, you're, you've got, you've got something that's really hard and then you're scratching it with something that you're claiming is not as hard, right. But then how are you scratching it? Right. Yeah. If the, if the original thing is thing is not as hard, right? And if are you really sure that the scratch you made is like enough to give you data for the Vickers hardness scale, right, right.

42:18If it's harder than the thing that you're using to scratch like like we're in unknown territory here because usually when we talk about how hard is something, we take a normal diamond that we know is at A hardness of 10 and we scratch it and then we see what the indentation is. And then from that you can calculate, OK, where is it on the hardness scale here? You're saying this is harder than the thing we're using to probe it, right? Doesn't make any. Sense No, it it it does the the radio speaker dial does not go to 11.

42:43Yeah. OK, so that's reviewer 1, Reviewer 2, what's very nice about it, OK, he said. You know, bulk hexagonal diamond is a very important thing. Therefore, the study seems important and could deserve to be published in a journal like Nature. He's saying you've got a chance, but I'm not convinced. He says the data obtained from these many different methods to characterize the sample looks convincing in principle, but there's some important questions that remain.

43:08So the authors go back. And the key thing is with Reviewer 2, the concerns that he said, the important questions that remain are very similar to author 1 to reviewer one. Yeah, except reviewer one was straight up like, yeah, this is not this. I don't know what are. We doing here? Yeah. Okay, so the authors come back and they did do multiple directions. Okay, so in this one, if you see this is Figure 22A and B show AB stacking, you see that? You see the little orange dots, That's A B, A/B, A/B, A/B.

43:40This is electron microscopy. Very clear. Yes, very clear. Right on the bottom row, you see hexagonal lattice. Yeah, yeah. Yeah, OK. Yeah, it is quite. It's like it's there, right? The ABAB stacking is in the top row. They've they've done the simulation on the right hand side of like what it should look like. And on the bottom row, yeah, they're they're they're showing the hexagonal stacking. Yeah, very nice. Yeah, yeah. OK, so. And this is exactly what the peer review process is. Yeah, like this is the point is, is that we want to get things accurate as accurately as possible and as correctly as possible.

44:13And so it's a, it's a natural back. It's a natural back and forth and credit to the editor of this thing. He didn't take the Reviewer 1 feedback too seriously and gave the authors another chance, right? Yes, especially because I mean reviewer 2 had like positive things to say and said that there is definitely a chance. I think if both editors, I mean if both reviewers were like, no, yeah, it would have been kind of bad, right. So anyways, they did show the multiple directions. They showed that ABAB stacking and the hexagonal stuff, They also did this right, Feld analysis. This is a kind of computational trick where you say, OK, what if, what if the sample is fully hexagonal or it's a mixture of hexagonal and cubic?

44:52What would the theoretical distribution look like? And then if I take a difference of the two, which model fits better? And the one that's purely hexagonal fits better than the one that's a mixture. OK, so this is the analysis that reviewer one wanted. He got it. So the other thing, there's a question about uniformity. How uniform is the sample? Which is a good. Which is a good question. So here they took 11 different random samples of like a part of their sample and they did X-ray diffraction on that to show that the X-ray diffraction that comes out of whatever part of the sample is pretty identical. Right, this is.

45:28These are 11 different X-ray diffraction experiments, but they all look basically the same. Like the the spacing of the Yeah of the maxima Yeah of your X-ray diffraction is about the. Same. Yeah, right. It's also just beautiful. Yeah, very beautiful. And the hexagonal structure that you see is indicative. Yeah. Like, like it's like, yeah. I have never looked at that much. Yeah. Extra crystallography or electron microscopy? Microscopy photography. But you can.

45:56I can see the thingy. Yeah. Without much analysis, yeah. And finally they also, instead of doing the Vickers hardness scale, which is like the scratching on the diamond thing, reviewer one suggested that they should do something called pulsed echo experiments. This is a way that you can basically send sound waves effectively through a material and the response of that material lets you calculate the elastic modulus of that material. And then there's ways to back calculate what the hardness is. So he said if your scratch test and this echo experiment give you the same number, then I'll believe you. So they did it.

46:34It did come out, it showed that the Young's modulus was bigger than diamonds. And so finally version 3, which is the fourth version because you start with version 0. So with version 3, reviewer one finally says that he's happy with the version. He says the author's revised the paper according to the recommendations. Now the paper and supplement provide all the relevant information and the results are truly convincing. Exclamation point. And at the end and in the middle he's saying that I believe refining all of this was worth it. So he's kind of saying, like, I know I gave you guys a hard time, but I think it was worth it because now I think this paper is stellar.

47:10And at the end, he says congratulations for this important work. And he signs his own name. Oliver Chauhanar. Yeah. Yeah. He's from the University of Nevada, Las Vegas, I believe. So he did. He put his name. He doesn't have to. Right. Right. But he put his own name there to show. OK, this is who I was. Yeah. I appreciate the work you did right. So reviewer one turns out to be like kind of a hard ass, but right, The paper is quite incredible because now no one can say. Anything.

47:37No, this is, and I think this is the key point why I wanted to preface the cultural moment and the sort of judgement of, you know, it, it, it, this process really doesn't matter. And I do think some of the feedback that was brought up makes total sense. Yeah, yeah, yeah. Like very reasonable. And like reviewer 2 said, the same stuff, right? Yeah. And if it worked, it's it was easily resolvable, yeah. It didn't require huge refactor or anything like.

48:01That you've got the sample. Just yeah, do a little more double checking. Yeah. And fascinating. Yeah. And this is, and again, we covered this in episode 5, right? And in it's slightly different, little similar but slightly different way. Yes. So now let's talk about that. OK. All right. So this particular paper is coming out of Zhengzhou University in China, also Nanjing University in China, and you said Hunan University, right, in China. These are all sort of like in the northern central part.

48:31And China. And I want to just pronounce and. In the East. Hanan versus. Hunan okay, sorry. Just be okay, because they're fair. Sure, totally enough. And the paper that we covered last year was out of the Shanghai Advanced Research in Physical Sciences Center in China, right? And that was synthesis of bulk hexagonal diamond already Funny because these guys use synthesis of bulk hexagonal diamond and these guys just like bulk. Hexagonal diamond. Right. OK, also in Nature now this new paper does not cite. No, no.

49:10OK, I thought that was pretty hilarious because the reviewer comments in reviewer 2 actually does acknowledge this, that a recent paper has come out that shows bulk hexagonal synthesis of bulk hexagonal diamond. But he says that this paper was submitted before that one got accepted. So it's not like these guys knew about that paper, right? But what that also tells me is that these guys, Lai and other authors from Zhengzhou University, had the chance to cite that paper and did not because they saw it in the reviewer comments. Also, if you're in the field, you're not going to not be aware of a Nature paper that came out saying the same thing. Right.

49:53Right. And in they were in the process of revision, which means they could have easily snuck in that that, but they didn't. OK. I think already that's hilarious. Yeah. Yeah, Yeah. OK. There's clearly something. We didn't sample your your your chord from your 1967 hit no no. No, no, no, yeah, yeah. And that same, that same group from the Shanghai University also did another paper in February, but this was in Nature Materials and again, it was a general approach for synthesizing hexagonal diamond using post graphite phases. So slightly different method but still no mention of even this paper.

50:32This is like this is some beef. Dude, yeah, this is what beef looks like. Yeah, in the research. Really, there's something right So so I wanted to dig a little bit deeper yes. So Nature has a news article about this, right, where they talk about this, they talk about like this paper and all of the other research around it. And Nature being Nature, they have to acknowledge that they themselves published a previous paper, right? Right. So what, what's going on, right?

51:02So I'm just going to read a little bit snippet of that, of that news article, right? First of all, we we see Schoner, who's the the reviewer #1 he gives a brief expose about like, he says that the pattern of the depression peaks that are obtained very closely mimic that of hexagonal diamond. And to demonstrate hexagonal structure conclusively, there's a few more peaks that I really wanted to see once I saw that the new paper shows those peaks. That's why I believe it.

51:34OK so he's he, you know, kudos were reviewer #1 gave them a hard time but. And then went to go comment on the public. On the public thing and said I was the reviewer, I believe it. I stand by this paper along with the author. Right, which is a crazy. Yeah. OK, You know, that's cool. Yeah. Right, Yeah. Now they mentioned last year another research group independently reported making hexagonal diamond. This is the 2025 paper, Yes, out of Shanghai. And they get a quote from those authors, from the from the from last year's paper. And that guy Ho Kwang Mao from Shanghai, he says it looks like the new paper is very similar to ours. I have to say I cannot see any difference. He's quoted right.

52:20And then and then and then he says, but we're glad they have reproduced our results, which is effectively a scientific way of saying they didn't do anything new, right? They just, I can't. It's effectively they're saying, I can't believe a reproduction paper. Yeah, right. Also got into nature, right. So something happened, bro. Yeah, like something happened with these two groups and shot Schauner, who's the reviewer #1 he did a minor clap back. He said it's almost the same.

52:51But he pointed out that the X-ray analysis by Mao and his colleagues, this is the previous paper that X-ray analysis lacked one or two of the diffraction peaks that are expected to be seen in hexagonal diamond. So he's saying this paper has a definitive right like hexagonal diamond X-ray diffraction pattern, right, that perhaps the other one didn't right. But I just this whole Sega is hilarious to me and and you. Actually brought this up when we did episode 5 where you you said I think there might be another team yes that is working on this. Within China.

53:25Within China, but the this these guys got out first. Yeah. And you had literally like it was. I wish I will try to see if we can do a like our our, our throwback thing here, because your statement on that episode is almost literally, yeah. And it turns out it was this, It was this team, It was that that was doing it. I mean, so two things. One, this is hilarious. I love scientific beef and beef among scientists. I wonder what conferences are like. Yeah.

53:53You know. Because because I think the point is like this is this is it is A50 plus year old yeah, unsolved problem. So the prestige and the street cred and yadda yadda that you'll get from it. Yeah for being first yeah matters yes, a lot, especially in the material size, because this resolves the simulation like people who are Pooh poohing all The Sims are wrong. Well, I guess not. Yeah, I guess not. I guess this thing is real, right? So that's one thing. This is hilarious.

54:26And science beef is also funny, I think. 2:00 this shows just how good China has gotten. Yes, with fundamental material science research. Yeah, because they're having internal beef. Right. Right. OK. Yeah. There's institutions within China, yes, that are beefing with each other, right? About like who came first, right? It's not even China is saying we're first, right? It's like who among us is first is first, right? It's China. Chinese science has made leaps and bounds in terms of where they were just 20 years ago compared to where they are now, right?

55:01Yep. Where 20 years ago this kind of competition was unheard of, right? And now and now we're we're at this stage. It is. It's very impressive. If you're watching this on a clip, be sure to watch the full episode because the details are very juicy. Yeah, the actual science is fascinating. Why it worked is fascinating. How much grief the reviewers gave them, right? This was not easy for these scientists to publish. Right. And and this is not coming out of the South China Morning Post, no or you know an outlet that you can perceive to have geopolitical reason to frame it one way or another.

55:39And also the material science implications of this as you brought up at the beginning from industrial application etcetera. Obviously there's a scaling issue, yadda, yadda, all this normal stuff. We caveat regardless, hugely, hugely impactful and and I think sort of we'll see how the, because we, we're, we've this is now 6-7 months later from our first coverage. Yeah, we'll see how the story progresses, but this seems to be a little bit of the closing of the book on a couple of the aspects.

56:10Yeah, yeah, I think, I mean, there's two, there's two big research groups that have shown that this thing can work. I'm sure now other countries and other labs are going to replicate this thing. Now the big question mark is, can this thing scale or do we have to figure out a new way to create hexagonal diamond that scales industrial industrially, right? But it works. Yeah, and we can do it. Great story again. Out of Out of nature on March 4th, Zhang Zhao, Nanjing and Hanan Universities in China. A fall to our episode 5.

56:45If you liked this episode, if you like against seeing the connections, our last deep dive episode at a very similar thing. If you're a long time listener, you're probably like me where you're starting to get these things much quicker. You can see how they all relate to each other, how we build on top of the past work. We are truly standing on the shoulders of giants. Now. Should we ask for the comment for this episode to create a replacement for the De Beers? Diamonds are forever.

57:13Some diamonds marketing, yeah, some not. Diamonds are hexagonal, but something. Something yeah, come up with your best tagline. Best tagline because we need a rebrand for diamonds now because it's technically a different thing, Yeah. There's. Two types. There's two types. Two types. I am your host. Lesson are I joined as always by my Co host and our resident PhD Krishna Chowdhury. We appreciate you all joining us on this journey and we will see you later this week.