From First Principles - Harder Than Diamond? The New Hexagonal Diamond Breakthrough (EP 38)

Episode Date: April 15, 2026

Hosted by Lester Nare and Krishna Choudhary, this episode is a deep dive into one of the strangest and most hard-fought materials science stories in decades: the claim that researchers have finally synthesized bulk hexagonal diamond, also known as lonsdaleite. They break down why this material matters, how it differs from ordinary cubic diamond, why scientists argued about its existence for more than 50 years, and what the new Nature paper actually did to convince skeptical reviewers.SummaryWhy hexagonal diamond matters — if real, it is a long-sought carbon phase that could be slightly harder than conventional diamond and useful in extreme industrial settings.The first-principles chemistry — carbon allotropes, x-ray crystallography, cubic diamond, and the ABAB stacking that makes hexagonal diamond different.The experimental breakthrough — how the new team engineered around the default pathway to ordinary diamond by controlling graphite orientation and pressure direction.The controversy — why the peer review was intense, and how the new paper relates to an earlier 2025 Nature paper with a similar claim.Support the showDonate: FFPod.com/donateFollow: @FFPod on X / Instagram / TikTok / Facebook

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This is... Like this is some beef, dude. Yeah, this is what beef looks like in the research committee or something, right? Hello, internet. This is your captain speaking. Lester Nare, joined as always by my co-host and our resident PhD, Krishna Chowdary. Today, we're going to be diving into a paper that is actually a follow-up to our episode five story on unbreakable hexagonal diamonds. This 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. And 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 1960s. and material scientists have been seeking this holy grail ever since. Okay.

There's been debate about whether it even exists in the first place. Okay. Okay. 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, okay? It's not just used as jewelry. In fact, 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-tipped drill bits. They can board through rock for any type of stuff, oil exploration, mining, anything. Diamond-coded 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. Diamond 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, oh, interesting. Diamond is a really good insulator, and it's also a really good heat sink in the means that 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. this is why everyone is saying that, you know, the data centers up in space won't work. Right.

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. Diamond is one of these things. And imagine now you can make an upgraded diamond.

that's going to upgrade all of these 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 and the arrangements of that material, I put that into a computer, and I ask the computer to just churninger's equations and what we know about physics and material physics. if we do that in computer simulation, those simulations suggest that this thing is real.

But 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. That theoretically this thing should be possible.

why is it so hard and is it even possible, right? Because if it's truly not, then we have to go back to the drawing board on fundamental material science. And that is a very uncomfortable scenario for everyone in the field. Right. Right. Yes. And so the status now is we've got a team in China that's 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, you we covered a story in... 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. We got the tea, everybody.

Okay, so let's start from the basics. Yes. Carbon. Carbon is the sixth element on the periodic table. it has six protons in its nucleus, usually six electrons, usually six neutrons in its nucleus, sometimes seven, sometimes eight. But six protons in the nucleus mean you've got six electrons revolving around the atom. Two 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, there'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 eight. So if you have three, that means you can have like five holes. But with four, you can either give four or you can

take four. So you can make the most bonds that way, right? Oxygen can only really make two bonds. The other ones can only make whatever is less, but four is right in the middle where I can give four or I can take four. So I can make the most number of bonds. That's why it's so important in organic chemistry for life and 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. Yes. 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? Well, 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's son duo to win the same Nobel Prize. And he was 25 at the time, the youngest Nobel Prize winner in the sciences. He went on to be the head of capital, Kavnish Lab at Cambridge and managed the empire that was Kavanaish Lab at Cambridge University. The idea is the following. You shoot x-rays at a 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 see some of the fashions that they're arranged.

But in any case, it's like Lego blocks that are repetitive. And 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-rays added up and other spots where the x-rays canceled out. And using that pattern, I can discern what is the structure of the crystal inside. Okay? That's the whole game with x-ray crystallography. As a crude analogy, it's almost like making hand puppets with a light source on a wall.

And you're looking at the shadow to determine what is the actual figure. Yeah, that's basically it. But in like all three dimensions with like frequency. and everything. Extremely much more complex. Yes, 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. The 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. Yes. 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 four bonds. All four bonds are other carbon atoms. This thing is extremely tightly packed. Okay? And it's single bonds that are going in. Yes. Okay.

So that's the fundamental unit of stacking. It's a cube. Hence, normal diamond is called a cubic diamond. Yeah, right. Okay. 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 Trotinger'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. Okay? The question is, is that real? Right. So, 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 been to the Grand Canyon, the south side, there's 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. 50 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. Okay?

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.

Lonsdelight, a hexagonal polymorph of diamond. They're saying that they found that hexagonal polymorph that was suggested in theory five years ago, right? They named it Lonsdelight and just a brief sort of digression into why Lonsdelight. It's named after Dame Kathleen Lonsdale. she was a foundational x-ray crystallographer and prison reform advocate. Very, very cool person, okay? She pioneered the use of xray crystallography. She actually did her PhD under William Henry Bragg, the dad.

Yep. Okay. And she wanted to understand the structure of aromatic compounds. Specifically, she figured out that benzene, which is a six 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 Xero crystallography, she's the first one to figure out how to quantitatively use the mathematical theory to understand even more complicated patterns with extra crystallography. 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 Rosalind 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? And Francis Crick was the one who figured out, okay, it's got to be a spiral. Right. And the spacing of the DNA, 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 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 II because they're very nonviolent 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. So, 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 are 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 in 1967 by Frondell and Marvin, they claimed to have found the hexagonal diamond. They named it after Dame Kathleen Lonsdale. They call it Lonsdelight. They did x-ray diffraction on this thing, and they showed that it has the same pattern as something called Wirtzite, which is a zinc sulfur mineral that has hexagonal symmetry.

Here, what you're looking at is an animation of Wirtzite. 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. There's two things that are different about this compared to the cubic diamond. Okay. 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. Yes. 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 degree 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, this thing is going to be harder. Right. Than cubic Diamond. Yes. Okay. 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 Wartzite 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. Yeah. 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 at a grand scale, not just that, okay, the fundamental unit is hexagonal rather than cubic. Yes. That's the first thing. But now let's consider like packing a bunch of carbon atoms like spheres in a enclosed space. Okay. How do we do that? Well, there's two ways of doing it. On the left is your cubic diamond. Okay?

That's 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 an A, B, C, A, and, A, B, C, A, B, C 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. The 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 three distinct layers, and it'll repeat like that. Yep. Okay? With hexagonal diamond, just because of the nature of the geometry, I only need two 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. So my stacking is going to go A, B, A, B, A, B, A, B, instead of A, B, C, A, B, C.

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 very obvious visually. It's kind of hard to describe just with audio 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 so you know the cubic diamond is almost like three steps on a staircase yeah where the offset on the sea 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 two very versus three, you can already think, structurally, that it would be. It would be better.

It would be harder. The things would be closer packed. Right. The 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 socials. Right.

So, okay, Discovery in the 19th. 1960s, this is when they're like, okay, I think we found it, right? Yes. So 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 effectively high pressure, high temperature. Yeah. Okay. So you take graphite, you would subject it to 10 gigapak skulls, which is 100,000 times atmospheric pressure. You raise the temperature up to a thousand degrees.

And you get diamond. This was a triumph in material science, Francis Bundy, Paul Strong, and Wentworth. They got enormous recognition. 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. And then you give it to the other three, 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?

So 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 diamonds. It's peak pollination season, and my business is scaling fast.

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Yes. Is because the way you make diamonds is through it. It's almost like like almost most people kind of know it's like heat 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 De Beers Corporation. As hard as a diamond, diamond under pressure, that's physics. Right, right, right, right. Just to be clear. Yeah, just to be clear, there is a difference here in how we approach things. So people start making lab grown diamonds and now we want to make Lonsdelight. We want to make hexagonal diamond. We've made cubic diamonds. We still have not yet made the thing we've already theoretically. identically identified as being 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. Right. So with all of this come skepticism.

It's like, well, why can't I just make hexagonal diamond? How come every time I'm trying to make diamond, I always get cubic diamond, which is the stuff that I see on Earth. And now you're telling me that since meteor or has it, but 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. It's just like, no, this is fake. For those who might not understand, this is like death the death. definition of a clapback.

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. Yes. Right. And so here is the argument that he's making. He's saying that Lawns of the Light is just cubic diamond but with something called stacking faults.

What he's saying is if you look at the meteorite samples. Okay. There's a bunch of cubic diamond lattice structure, but that cubic diamond lattice structure is not contiguous. There's like cubic diamond here, and then there's another domain of cubic diamond over here, and the boundary between them is slightly offset. 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 Kenyan Diablo meteorite. And he's showing that there are these

stacking faults, there are these boundaries, right? Yep. And so if you have enough stacking faults in your cubic diamond, the diffraction pattern is going to resemble the hexagonal stuff. And 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, oh, it's hexagonal. You can't say that. So he called it, it's Fugazi. Yeah. He's like, no, 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 through and you, and you put it in the

computer and the computer is saying this is fine. This is totally a possible allotrop of carbon. This works. The carbon atoms are all happy. They don't want to go into another phase. Like, you set them up like this, they'll stay like this. Based on the rules of just foundational and basic physics that we understand to be true, you can extrapolate in a computer and it's fine. Yeah, it's fine. It totally works. So, so what gives? Which means the theory of the case here is that it is an engineer. problem. Yes.

Not a fundamental physics or science problem. That's kind of what's been the argument. It's been the argument. But in order to prove that, you've got to just solve the engineering problem. Right. Right. And that requires a lot of fundamental physics at the end of the day.

And so in 2024, we're at this interesting state, right? The theory says, Laws the Light should be real. The experiment says, nah. This is where we get into this paper. Bulk hexagonal diamond. Great name. Yes. Three word.

I haven't seen a shorter nature paper title, to be honest. Well done. Right? Well, ball hexagonal diamond. That's it. That's it. That's it.

Nature. No, narrating. Yeah. Yeah. 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. Okay. They're showing that it's not an artifact. Mm-hmm. 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 five when we talked about the other group of Chinese teams that did the story, 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. The Nobel Prize aspect, all of these people, all these people and aspects that we really try to weave together is the joy that we get of doing the show. And you as the supporting community audience are a huge part of why we're able to do that. So a simple like, share, follow, comment.

You would not believe how much comments change how much our video gets shown to other people. Let's talk more about science, experimental design, breaking science research, and any way that you can engage in our content is super, super helpful for us getting this show to more people. If you would like to become a patron, you can go over to our website, ffppod.com, backslash donate, make a one-time donation. If 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 challenge is the following, actually. Okay.

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. And it turns out the cubic diamond, even though it's sort of bigger and has that ABC ABC stacking, that has a lower energy and is more favorable than this ABAB smaller configuration. So you've got to go through a very specific route in order to get to this local minima and avoid the global minimum.

That makes total sense. 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 not working. Other people had done that work. Okay? Yes. So this team is like, all right, how are we going to make a press? 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? Is it almost like saying we intentionally have to create an experimental apparatus that is not optimizing for the easy, like the best path? Yeah, yeah. Like, we're in tensed. Yeah, the easiest. We need to go and figure out some way to, like, go off. Off the, right.

You know? Right. Like, it's like we got two 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 chairlift.

Yes. In Mammoth, sometimes you want to go to the outhouse in the back to get your grilled cheese sandwich. Right. 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. Yes. And then have to wait like two hours to go up the mountain. We've all been there.

Yeah, we've all been there. But no, but that's actually really, that's a really interesting insight in that a suboptimal path can actually lead to the derivative effects that we are looking for. Yes. That are not necessarily naturally occurring. Yes, exactly. The reason why naturally occurring, diamond is always naturally occurring, that cubic diamond is, 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, very high speed, tens of kilometers per second slamming into rock. Right. Right.

This is a very key like scenario. Yes. So with that in mind, let's try to figure out how are we going to do this, right? Are we going to manufacture our hexagonal diamond and not cubic diamond? They use something called a Kawhi type large volume press. So this was conceptualized by Professor Naoto Kawhi. 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. Okay? 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 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, I can just like make the thing hot from a variety of different mechanisms. Because 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, in 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, okay?

What I want is exactly flat graphite, okay? Not off where like some carbon atoms are closer than other carbon atoms. I want exactly flat. 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? The advantage there is that the graphite itself has ABAB memory. Oh, very interesting.

You see where it's going? Yeah. Yep, yep, yep. The cooking, the material that they're trying to cook with already has the G. of their end product. Right. Right. And naturally occurring graphite is naturally imperfect. Yes. And those imperfections lead to getting to lead to the destination of the global minima. But, and, oh, that's so interesting. But because we are now making sure that we're having A5 Yagu beef going in and not around the corner grocery store beef going in, we're going to get exactly what we want is the chef. on the outcome.

Exactly. And so this, you can already see the A-B-A-B 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 preserved. That makes sense. There's another problem, though. Just because you start with A-B-A-B-B-G graphite, right?

It's going to be A-B-B-B-1-top of the other. If I push from all directions, that might cause the graphite to scrunch up, losing that symmetry. So I need to be able to only press from the top and bottom. Okay. Okay. 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. Yes. Okay? Yes. Once 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 AB-A-B graphite. Yes. And you can see a tiny defect is forming. And as you press, the orange is that hexagonal diamond. It rapidly forms, right? There is kind of a nucleation zone where the defect kind of starts and the layers of graphite are covales. bonding to one another.

And then as you press more and more, it rapidly sort of like a contagion. Yes. Right? That bond sort of spreads out. It propagates from this like initial inciting incident location. And this is so now understanding the component parts, this makes a lot more sense in terms of, you know,

because normally what you would get in the, this use case is the spreading of cubic diamonds. Yeah. 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. It's only, yeah. And as you can see, it's only being squished this way vertically, right?

It's not being squished the other way. Right. Right. And so 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 graph. 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. And obviously for like this type of paper, you want to show the mechanism. Okay. So this was a very cool molecular dynamic simulation that they're showing. So they do the, 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. Before everything was like submicron 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. Okay? Yes. And the idea being it both passed is just like the kind of the sniff test because of its size. It's just like, oh, well, if you can't make it that big, then it, I don't know.

care, but 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 vicar's 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 like 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 they also do the vickers hardness scale now i can read the peer review yes okay So what do you think, right? The peer reviewers are going to read this. I just want to note really briefly because, you know, there is a little bit of a, in the zeitgeist right now, there is a public debate about Chinese universities.

Yeah. And the legitimacy of the work that they do. Yeah. I'm saying this is what the zeitgeist conversation is like in the U.S. And this was published in nature. Yeah. Which is a Springer publication from the UK. So, you know, and

they're, what's great at which you talked about this recently is they're now putting the reviewer notes on these papers. Yeah. So you can get a little bit more of an insight into how the sausage was made. Yeah. To make a better characterization about your own perspective

of the study. Yeah. And so I'm just, I know that there's, I think there's been a little bit of poo-pooing that's been undeserved. Yeah. 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, okay, I mean, if it's bulk of hexagonal diamond, this does deserve getting published into nature. So now I'm going to put it off and give it for review to some of the top scientists in the field who know what they're talking about, okay? In this case, reviewer one comes back after version zero, and he says, overall, this paper should be rejected. Classic.

Classic. Usually it's reviewer two. Right? Because like reviewer one is like, because imagine you're like opening up your peer review file, right? And usually like reviewer one is like kind of nice about it. And then reviewer two is just going at it. Here like I guess the editor didn't change the, you know, because the editor could have just like changed. It doesn't matter who reviewer one and two is. Right. But anyways, they open up the peer review file and imagine the first overall this paper should be rejected. Okay. Yes. So here's the complaint that reviewer number one. 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?

So we can't see. But apparently they were inconsistent and they didn't analyze different axes. Like 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. 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. Okay. Which apparently like everyone does, so they didn't do that. Okay. And they're using, this one I thought was really hilarious.

They'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, yeah. 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 original thing is not as hard. Right. And are you really sure that the scratch you made is like enough to give you data for the Vickers hardness scale?

Right. Right. If it's harder than the thing that you're using to scratch. 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, okay, where is it on the hardness scale?

Here you're saying this is harder than the thing we're using to probe it. Right. It doesn't make any sense. No, it does. The radio speaker dial does not go to 11. Yeah. Okay. So that's reviewer one.

Reviewer two is very nice about it. Okay. He said, you know, bulk hexagonal diamond is a very important thing. Yes. Therefore, the study seems important and could deserve to be published in a journal like nature. He's saying you've got a chance. Yes. But I'm not convinced.

Okay. 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. So the authors go back. Yes. And the key thing is with reviewer two, the concerns that he said, the important questions that remain are very similar to author one. Okay. The reviewer one, except reviewer one was straight up like, this is not. This, I don't know what we're doing here.

Okay. So the authors come back and they did do multiple directions. Okay. So in this one, if you see, this is figure two, two A and B show A, B stacking. You see that? You see the little orange dots. That's A B, A, A, B, A, A, B.

This is electron microscopy. Very clear. Yes. Very clear, right? On the bottom row, you see hexagonal lattice. Yeah, yeah, yeah. Okay? Yeah, it is quite clear.

It's like, it's there, right? The A, B, A, A, B stacking is in the top row. They've done the simulation on the right-hand side of, like, what it should look like. And on the bottom row, they're showing the, hexagonal stacking. Yep. Very nice.

Yep. Okay. 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. Yeah.

It's a natural back and forth. It's a natural back and forth. And credit to the editor of this thing, he didn't take the reviewer one feedback too seriously. Right. Right. And gave the authors another chance, right. Yes.

Especially because, I mean, reviewer two had like positive things to say and said that there is definitely a chance. chance. I think if both editors, I mean, if both reviewers were like, no, 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, okay, what if the sample is fully hexagonal or it's a mixture of hexagonal and cubic? What 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. Okay? So this is the analysis that reviewer one wanted. He got it. Yes. So the other thing, there's a question about uniformity. How uniform is the sample? Which is a good question. 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. Wow. This is... These are 11 different x-ray diffraction experiments, but they all look basically the same.

Like the spacing of the of the maxima of your extra diffraction is about the same. Yeah. And it's also just beautiful. Yeah, very beautiful. And the hexagonal structure that you see is indicative. Yeah, like, I have never looked at that much

extra crystallography or electron microscopy photography photography. But you can, I 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. Okay. This is a way that you can like basically send sound waves effectively through a material. Yeah. 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. That makes sense.

So he said, if your scratch test and. this echo experiment give you the same number, then I'll believe you. Okay. So they did it. It did come out. It showed that the Young's modulus was bigger than diamonds. And so finally, version three, which is the fourth version, because you start with version zero.

Yes. So with version three, 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. And at the end, he says, congratulations for this important work.

And he signs his own name, Oliver Chowenor. 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, okay, this is who I was. Yeah. Appreciate the work he did. Right. Right. So reviewer one turns out to be like kind of a hard ass, but the paper is quite incredible. Because now no one can say anything. No, this is, and I think this is the key point of why I wanted to preface the cultural moment and the sort of judgment of, you know, this process really does 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 two said the same stuff. Right. Yeah. And if it worked, it was easily resolvable. It didn't require a huge refactor or anything like that. You've got the sample.

Just do a little more double checking. Yeah. And fascinating. Yeah. And again, we covered this in episode five. Right. And it's slightly different, a little similar, but slightly different way. Yes.

So now let's talk about that. Okay. 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 of China.

And I want to just pronounce it. And in the east. Hanan versus Hunan. Okay, sorry. Just be. Oh, okay. Because they're different. Fair.

Fair. Totally enough. And the paper that we covered last year was out of the Shanghai advanced research. Yes. 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 ball kick diagonal diamond.

Right? Okay. Also in nature. Yes. Now. Wishing you could be there live for the big game, soaking up the atmosphere of the crowd. But too often, life gets busy. Or the price holds you back. Priceline is here to help you make it happen.

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I thought that was pretty hilarious. Because the reviewer comments, in reviewer too actually does acknowledge this, that a recent paper has come out that shows bulk of cyclical, the synthesis of ball 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? Right. But what that also tells me is that these guys lie and other authors from Zhengzhou University have. had the chance to cite that paper and did not. Yes.

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. Right. And they were in the process of revision, which means they could have easily snuck in that. Yep. But they didn't.

Okay? I think already, that's hilarious. Yeah, yeah, yeah. Okay, there's clearly something. We didn't sample your chord from your 1967 hit. No, no, no, no. Yeah. Yeah. And 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. This is... Like, this is some beef, dude. Yeah, this is what beef looks like in the research committee. There's something, right? So I wanted to dig a little bit deeper. Yes. So Nature has a news article about this, right?

Where they talk about 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's going on? Right. So I'm just going to read a little bit snippet of that news article, right? First of all, we see Shauner, who's the

reviewer number one. He gives a brief expose about like he says that the pattern of the defression 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. Okay. So he's, you know, Trudeau's word, reviewer number one, 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 authors. Right. Which is a crazy... Yeah. Okay? 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 out of Shanghai. And they get a quote from those authors. Oh, no.

from the from last year's paper. And that guy, Hokwang 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? 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. also got into nature. Right. So something happened, bro. Yeah. Yeah.

Something happened with these two groups. And Shauner, who's the reviewer number one, he did a minor clap back. Yeah, he said it's almost the same. Yep. But he pointed out that the x-ray analysis by Mao and his colleagues, this is the previous paper. Yeah. That x-ray analysis lacked one or two of the diffraction peaks that are expected to be seen in

hexagonal diamond. Mm-hmm. Mm-hmm. So he's saying this piece. has a definitive, like, hexagonal diamond x-ray diffraction pattern. Right. That perhaps the other one did it. Right.

But I just, this whole Sega is hilarious to me. And you actually brought this up when we did episode five where you said, I think there might be another team. Yes. That is working on this. Within China. Within China. But these guys got out first.

Yeah. And you had literally, like, it would, I wish I will try to see if we can do a, like, our throwback thing here because your statement on that episode is almost literally exactly what happened. It turns out it was this. It was this team that was doing it. I mean, so two things.

One, this is hilarious. I love scientific beef. Yes. And beef among scientists. I wonder what conferences are like. Yeah. You know? Because I think the point is like this is it is a 50 plus year old unsolved problem. So the prestige

and the street cred and yada yada that you'll get from it. For being first matters. Yes. A lot. Especially in the material science. Because this resolves the simulation. Like people who are poo-pooing, oh, 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 and science beef is also funny. I think two, this shows just how good China has gotten. Yes. with fundamental material science research. Because they're having internal beef.

Right. Right. Okay. 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? Yep. Where 20 years ago, this kind of competition was unheard of. Right. And now we're at this stage. It is very impressive. If you're watching this on a clip, be sure to watch the full episode because the details are very juicy. 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 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. And also the material science implications of this, as you brought up at the beginning, from industrial application, etc.

Obviously, there's a scaling issue. Yeah, yada, yada, yeah, yeah, yeah. All this normal stuff we caveat, regardless, hugely, hugely impactful. And I think sort of we'll see how, because we're, we've, this is now six, six, seven months later from our first coverage. We'll see how this story progresses, but this seems to be a little bit of the closing of the book on a couple of the aspects.

Yeah, yeah. I think, I mean, 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 industrially? Industrily, right? But it works. Yeah. 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 up to our episode 5. If you liked this episode, if you like again seeing the connections, our last deep dive episode, had 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.

Some diamonds. Yeah. 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. Yeah. Two types. I am your host, Lestanari, joined as always by my co-host and our resident PhD, Krishna Chowdhary. We appreciate you all joining us on this journey, and we will see you later this week.

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