Harder Than Diamond? The New Hexagonal Diamond Breakthrough

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 hand. 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. >> is Yeah, this is what beef looks like. >> Yeah. >> In the In the recent company news >> there's something, right? >> Hello, internet. This is your captain

Intro — the follow-up to episode 5

0:27speaking. Lester Nare joins us, always by my co-host and our resident PhD, Krishna Choudhary. 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. This paper was published in Nature on March 4th of 2026 from three Chinese teams from Zhengzhou, 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.

The 50-year quest for hexagonal diamond

1:19>> 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 lonsdaleite. It's a form of carbon that was first proposed in the 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

Why harder-than-diamond materials matter

1:58about 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 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

2:39like that. But, diamond in its core is really effective in all sorts of industry. For example, diamond um diamond-tipped drill bits. They can bore 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. Diamond windows, they protect infrared sensors in 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

3:20in 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. This 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

4:02materials. Diamond 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 and the arrangements of that material, I put that into a computer, and I ask the computer to just churn Schrödinger's equations and the what we know about physics and material physics. If we do that in computer simulation, the simulation suggests that this thing is real. >> Mhm. >> But for the longest time, we don't have

4:43any 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 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 so a very uncomfortable scenario >> Right. >> 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

5:23pure 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. >> the tea, everybody. >> Okay. So, let's start from the basics. >> Yes. >> Carbon.

Carbon, bonding, and why it is special

5:59Carbon is the sixth element on the periodic table. It has six protons in its nucleus. Usually six six neutrons. 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. Yes. So, if you have three, that means you can have like

6:40five holes. But with four, you can either give four or you can take four. You can take You can make the most bonds that way, right? Oxygen can only really make two bonds. Um the other ones can only make, you know, 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 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. Um that's pure carbon.

7:21Nothing 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?

X-ray crystallography explained

7:34Well, usually what we do is we do something called X-ray crystallography. This was um 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

8:14Prize in 1915, the only father-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 Cavendish Lab at Cambridge and managed the empire that was Cavendish Lab at Cambridge University. The idea is the following: you shoot X-rays at a crystal. >> Yeah. >> 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. And because they're repetitive, the X-rays are going to interfere at certain angles. And if I have a detector on the

8:55end, 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. >> Mhm. >> Okay? 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 uh yeah, on a wall, and and you're looking at the shadow to determine what is the actual >> exactly. >> figure. >> Yeah, exactly. That's basically it, but in like all three dimensions with like frequency and everything. >> Uh extremely more 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

9:36when we do this with diamond, we figure out that it's a cubic structure. This is what diamond looks like at the atomic scale. >> Mhm. >> 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 >> Mhm. >> 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.

What makes ordinary diamond so hard

10:08>> Yeah. >> 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, 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 the 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

10:48atoms. This thing is extremely tightly packed. >> Mhm. >> Mhm. >> Okay? >> Mhm. >> 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,

What hexagonal diamond is supposed to be

11:07researchers 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 Schrödinger'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 >> Mhm. >> and even more hard, okay? >> The question is, is that real? >> Right. >> So, 1962, they published this paper in nature and in the 1966-67

11:48they came up with the Canyon Diablo meteorite. There were people who were um 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'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 m 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. >> Mhm. >> Okay? Now, this meteor hit Arizona extremely fast

The meteorite origin of lonsdaleite

12:32and meteors are made a lot of out of carbon. There's a lot of carbon in meteors. >> Right. >> 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. >> Mhm. >> And so, in 1967 um a paper came out again in nature Lonsdaleite, a hexagonal polymorph of diamond. They're saying that they found that hexagonal polymorph that was suggested in theory >> Mhm. >> 5 years ago. >> Mhm. >> Right? They named it Lonsdaleite and just a brief sort of

13:12digression into why Lonsdaleite. It's

Kathleen Lonsdale and why the material is named after her

13:15named 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 X-ray crystallography. She actually did her PhD under William Henry Bragg, the dad. >> Yeah. >> Okay? And um she wanted to understand the structure of aromatic compounds. Specifically, she figured out that benzene, which is um a six-carbon ring with six hydrogens, that thing is a flat ring. >> Mhm. >> 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

13:55position 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 X-ray crystallography, okay? And so she laid the foundations of, for example, later on when X-ray 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 X-ray crystallography with the X. >> Yes. >> 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 uh Francis Crick was the one who figured out, okay, it's got to be a

14:36spiral. >> Right. >> Right? And 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 first to first two women elected to the Royal Society. Um 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 because they're very non- >> Yes. >> violent people, right? >> Yes. >> Um and she was in prison for a month and her experience in that prison was like she used that experience to become a

15:17passionate prison reform advocate. >> Right. >> So >> Yes. >> 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 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 Marvin, they claim to have found the hexagonal diamond. They named it after Dame Kathleen Lonsdale. They call it

15:58Lonsdaleite. They did x-ray diffraction on this thing and they showed that it has the same pattern as something called wurtzite, which is a zinc sulfur mineral that has hexagonal symmetry. Here what you're looking at is an animation of wurtzite. Just imagine instead of the two different colors, which are zinc and sulfur, all of them are the same color cuz 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. Right? There's a hexagon um face on the top and the bottom. And the other thing is you're actually packing the carbon atoms closer together

16:40because the tetrahedral

Why the hexagonal structure could be harder

16:42the tetrahedral surfaces are flat compared to and 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 than cubic diamond. >> Yes. Okay. >> And I have one just brief question on this visual just cuz there's as a layman the other visual difference here and I I understand that we're looking at wurtzite in this example and the key

17:24difference 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 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 >> showing one segment section. >> But because it's a crystal it's like going to just keep repeating. >> Makes sense. Just wanted 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 okay, the fundamental unit is hexagonal rather than cubic. >> Yes. >> That's the first thing. But now let's let's consider like packing a bunch of carbon atoms like spheres in a

18:07in a enclosed space. How would we do that? Well, there's two ways of doing it. On the left is your cubic diamond. >> Mhm. >> Okay? 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 ABC ABC >> Mhm. >> ABC kind of manner. Meaning you're going to get one layer of carbon atoms >> Mhm. >> the B layer which is on top is going to fit somewhere in the gaps of that. >> Yep. >> 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. >> Yeah, yeah, yeah. >> going to get three distinct layers and it'll repeat like that.

18:48>> Yep. >> Okay? >> Yep. >> With hexagonal diamond just because 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 >> Yeah. >> the next layer can just repeat >> Yes. >> the bottom layer. So my stacking is going to go ABABAB instead of ABC ABC >> Yes. And just for folks who may be listening, I just want to put a disclaimer. This is an slightly important episode for visual reference points because it's it's very obvious visually. It's kind of hard to describe. >> Uh it just with audio or or with voice,

Cubic stacking vs hexagonal stacking

19:29but 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. >> Mhm. >> 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. >> Uh where the offset on the C is significantly farther away from the A. >> Yeah. >> But in the hexagonal it's just two steps. Um and so imagine you're creating like this staircase that's going back and forth like this. >> Having two versus three >> Yeah. You can already think yes. >> structurally that it would be >> It would be better. It would be harder. The things would be closer packed. The bonds would be a bit stronger. The layers would be a bit stronger. And just

20:11theoretically 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. Discovered in the 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. >> Mhm. >> You know, lab diamonds. Synthetic diamonds. They invented it in the 1960s. This is General Electric. Actually 1954.

The first synthetic diamond and why it mattered

20:54They use a kind of belt apparatus. It's it's effectively high pressure high temperature, okay? So, you take graphite, you would subject it to 10 gigapascals, which is 100,000 times atmospheric pressure, you raise the temperature up to 1,000° 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. Um 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 three, you know? But they didn't even do that,

21:35which 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 should 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 uh 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 high heat >> Yeah. And squeezing. Yeah. >> diamond.

22:16>> 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. >> Hollywood. >> Right. That's Hollywood and the DeBeers corporation. The as hard as a diamond, diamond under pressure, that's physics. >> Right. Right. Right. Just to be clear. >> Yeah, 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 lonsdaleite. We want to make hexagonal diamond. >> We've made cubic diamonds. We still have not yet made the the thing we've already theoretically identified >> Exactly. Impossible. >> Yeah. Yeah. But there's a lot of problems. The samples are too small. The

22:57crystals 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 >> Mhm. >> worth of stuff >> Mhm. >> to do anything. >> Right. >> Right? 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 that 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

The 2014 “it does not exist” clapback paper

23:34um Lonsdaleite is faulted and twinned cubic diamond and does not exist >> Mhm. >> as a discrete material. What a banger of a title. >> Mhm. >> Okay? It's just like, no, this is fake. >> F- For those who might not understand, this is like def- the definition of a clapback. >> Yes. Yeah. No, 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 Lonsdaleite is just cubic diamond, but with something called stacking faults. What he's saying is, if you look at the meteorite samples, okay?

24:15>> 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 on over here, and the boundary between them is slightly offset. >> Yeah. 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 Canyon 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

24:56the 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 fugazi. >> Yeah, he's like he's like, "No, this is 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. >> Right. >> This is totally a possible allotrope of carbon. >> Yep. >> 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 of just foundational and basic physics that we

25:37understand to be true, you can extrapolate in a computer and it it's fine. >> Yeah, it's fine. Totally 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. the argument and but in order to prove that you got to just solve the engineering problem. Yeah, right? And

The new Nature paper: “Bulk hexagonal diamond”

26:01that 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 lonsdaleite 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? Bulk hexagonal diamond. That's it. >> That's it. >> That's it. >> No no no narrating, no just >> 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

26:42created. >> Okay. >> Um 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. 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 this show, and you as the

27:22supporting community and 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 ffpod.com /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,

28:04distribute, 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 to to 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,

Why making cubic diamond is easy and hexagonal diamond is hard

28:29let'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, >> Mhm. >> 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. >> Mhm. >> 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

29:10though it's sort of bigger and has that ABC ABC stacking, >> Yes. >> that has a lower energy and is more favorable than this ABAB smaller configuration. Okay? >> 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 total sense. >> Okay? 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 >> Right. >> Why is this not working? Other people had done that work, okay? >> So, this team is like, all right, how are we going to make a press? How are we going to make a an

29:50experimental 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 a uh uh an experimental apparatus that is not optimizing >> Mhm. >> for the easy like the best path. >> Yes. Yeah. Yeah. >> Like where it's Yeah, it's easiest. >> We need to go and figure out some way to like go off >> off the right right. >> Like it's like we got two depressions on a hill. It's like when you're skiing, right? You don't want to go all the way down to the the chairlift. You In Mammoth, you sometimes you want to go to the outhouse in the back to get your grilled cheese sandwich, right? But that

30:31requires 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 done that. >> Yeah, we've all been there. But no, but that's actually a really That's an a really interesting insight in that a suboptimal path >> Mhm. >> can actually lead to the the derivative effects that we are

The experimental trick — pressure pathway and local minima

31:00looking for. >> Yes. >> That are not necessarily naturally occurring. >> Yes, exactly. The reason why naturally occurring diamond is always naturally occurring that cubic diamond is because it's not a controlled process in the Earth's crust, right? So, it's just easy for the carbon to settle into the natural cubic diamond. But if we really want to go for this hexagonal thing, it's got to be real tight and real specific. And perhaps that's why the meteorite was showing these cases, right? Because like I mean, the scenario is crazy. It's a space rock coming at like it's very high speed, tens of kilometers per second, slamming into rock, right? This is a very key like scenario. >> Yes.

31:40>> That makes sense. >> So, so with that in mind, let's try to figure out how are we going to do this, right? How are we going to manufacture our hexagonal diamond and not cubic diamond? They use something called a Kawai type large volume press. So, this was conceptualized by Professor Naoto Kawai. It's a uniaxial hydraulic press with six steel anvils that are inward. Here's the key idea here. There's multiple stages. There's the inner stage, then there's the second stage anvil, and then there's an outer stage anvil. What I'm going to do is press. And when I press, the intermediate stage is going to press from all directions.

32:20Okay? So, it's not just going to give me this kind of force. It's going to give me an all direction type of force. And then that all direction type of force is going to press on a even smaller thing that is going to then let me control how >> Mhm. >> and in what direction and how much I am able to put pressure. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can

Why highly oriented pyrolytic graphite matters

32:55just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different mechanisms. So that's my high pressure and then high temperature I can just like make the thing hot from variety of different 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 some carbon atoms are closer than other carbon atoms. I want exactly flat. So they created a high

33:37pressure 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. Very interesting. Yeah, yep, yep. Yep. The cooking the material that they're trying to cook with already has the geometry of their end product. Right. And and naturally occurring graphite is naturally imperfect. And those imperfections lead to getting to lead to the destination of the the

34:19global minima. But and oh, that's so interesting. But because we are now making sure that we're having A5 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 outcome. >> Exactly. And 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? >> Yes. >> 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 cuz you start with ABAB graphite, right? It's going to be ABAB one on top of the other. If I push from all directions,

35:02that 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,

35:42finally this is how it should work in theory. They did large-scale molecular dynamics simulations. Here we've got layers on layers of that ABAB 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'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, >> Yes. >> right? That that bond sort of spreads out. >> It it propagates from this like initial inciting incident location. And this is so

36:24now understanding the the component parts, this makes a lot more sense in terms of, you know,

The molecular dynamics simulation

36:33because normally what you would get in this use case is the spreading of cubic diamond, yeah. But because we've created our uh 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 >> yeah, and 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. >> 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. And so this is the molecular dynamic simulation that they where they show this is how we think it should happen. This is part of their paper, and

37:14all 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. You've got some pretty large samples, so that bar is 200 microns. 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 sub-micron level. Like I had to go into the Canyon 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.

37:55>> Yes. >> Okay? >> Yes. And and the the the the idea being it 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." 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 Vickers hardness scale.

The first characterization results

38:30On the left, you're seeing the um x-ray diffraction. >> Yes. >> 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 is hexagonal diamond. They also do the Vickers hard hardness scale. Now I can read the peer review.

The peer review begins

39:04>> Yes. >> Okay? >> Yes. >> So what do you think, right? The peer reviewers are going to read this and >> I just want I just want to note really briefly that because, you know, there is a little bit of a in the zeitgeist right now, there is a public debate about uh Chinese universities. >> Yeah. >> 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. >> Yeah. >> Um >> Which is a Springer publication from the UK. >> So, you know, and there what's great, which you talked about this recently, is they're now putting the reviewer notes >> Mhm. >> on these papers. >> Yeah. >> So you can get a little bit more of an

39:45insight 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 I know that there's I I think there's been a little bit of pooh-poohing 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, okay, I mean, if it's bulk hexagonal diamond, this does deserve getting published in the 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, okay? Um in this

Reviewer 1: “this paper should be rejected”

40:22case, 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 cuz 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, cuz the editor could have just like changed It doesn't matter who reviewer one and two is. You I 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

41:04basically 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, you know, with with a with a crystal, there's like different directions that I can sort of probe. I can just rotate my sample >> Yes. >> on my X-ray diffraction apparatus and then I can probe different directions of the crystal. They didn't do that. >> That's That's I think that's fair. >> That's that's totally fair. They also didn't do this thing called Rietveld refinement, which is a way to computationally clean up diffraction data, which apparently like everyone does. So, they didn't do that. >> Okay. >> And they're using This is This one I

41:45thought 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. Right? You're 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 >> thingy 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? If it's harder than the thing that you're using to scratch. Like Like we're we're in unknown territory here. Cuz usually when we talk about how hard is

42:25something, 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. >> Doesn't make any sense. >> It No, it it it doesn't. The The radio speaker dial does not go to 11. >> Yeah. Okay. So, that's reviewer one. Reviewer two was very nice about it. >> Okay. >> Um 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

43:06there's some important questions that remain. >> Mhm. >> So, the authors go back. >> Yes. >> And what the key thing is with reviewer two, the concerns that he said the important questions that remain are very similar to author one. >> Okay, got it. Yeah, yeah. >> Except reviewer one was straight-up like, >> Yeah, this is not good. >> This This I don't know what we're what we're What are we What are we doing here? Okay. So, the authors come back, and they did do multiple directions. Okay? >> Okay. >> So, in this one, if you see this is figure two, two A and B >> Mhm. >> show AB stacking. You see that? You see the little orange dots? That's ABAB >> Yeah. >> ABAB. This is um electron microscopy. Very clear. >> Yes. >> Very clear, right? On the bottom row,

43:46you see hexagonal lattice. >> Yeah, yeah, yeah, yeah. >> Okay? >> Yeah, it is quite it is quite clear. >> 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, they're they're they're showing the hexagonal stacking. >> Very nice. >> Yep, yep. >> Okay? So, >> And this is exactly what the peer review process is. >> Like this is The point was is that we want to get things accurate as accurately as possible and as correctly as possible. And so it's a it's a natural back and >> It's natural back and forth. And credit to the editor of this thing, he didn't take the reviewer one feedback too seriously and gave the authors another chance right?

How the authors fixed the paper

44:25Especially because I mean reviewer two 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, yeah. >> it would have been kind of that, right? So anyways, they did show the multiple directions, they showed that ABAB stacking and the hexagonal stuff. They also did this Rietveld analysis. This is a kind of computational trick where you say, okay, what if what if the sample is fully hexagonal or it's a mixture of hexagonal and cubic? >> Mhm. >> What would the theoretical distribution look like? >> Right. >> 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? >> Yeah. >> So this is the analysis that reviewer one wanted. >> Yes.

45:05>> He got it. >> Yes. >> So the other thing, there's a question about uniformity. How uniform is the sample? >> Uh which is a good question. >> Which is a good question. So here they took 11 different random samples >> Mhm. >> of like a part of their sample >> Mhm. >> and they did X-ray diffraction on that >> Mhm. >> to show that the X-ray diffraction that comes out of whatever part of the sample is pretty identical. >> Wow, this is this is >> These are 11 different X-ray diffraction experiments, but they all look basically the same. Like the the spacing of the of the >> maxima of your X-ray 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 like you it's like I have

45:46never looked at that much extra crystallography or electron my scratch microscopy microscopy photography, but you can I can see the

The hardness issue and pulsed echo experiments

45:57thingy without much analysis. >> Yeah, yeah. And 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 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. It did come out. It showed that the Young's modulus was bigger than

46:38diamonds. And so, finally, version three, which is the fourth version cuz you start with version zero. So, with version three, reviewer one finally says that he's happy with the version. He says, "The authors revised the paper according to the recommendations. Now the paper and supplement provide all the relevant information and the results are truly convincing 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 um Schauviller. >> Yeah, yeah. >> He's from the University of Nevada, Las

47:20Vegas, I believe. So, he did He put his name He doesn't have to, right? But he put his own name there to show, "Okay, this is who I was." >> Yeah. >> And my >> Appreciate the work he did. >> Right, 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. >> 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, it it it it it this process really does matter. And I do think some of the feedback that was brought up makes total sense. >> yeah, yeah. >> Like very reasonable. >> like reviewer two said the same stuff. Yeah. >> And if it worked, it's e- it was easily resolvable. It didn't require a huge refactor.

48:00>> Or anything like that. >> You got the sample. Just >> Yeah. >> do a little more double-checking. >> Yeah. >> And fascinating. >> Yeah. >> I I the the And this is And again, we

The scientific beef with the 2025 paper

48:09covered this in episode 5 and in a slightly different similar but slightly different way. >> So, now let's talk about that. >> Okay. >> All right? >> Okay. >> So, this particular paper is coming out of Zhengzhou University in um China, also Nanjing University in China. And you said Hunan University, right? In China. These are all sort of like in the northern Yeah. central part of China. >> I want to just pronounce it I think it's >> And in the east. >> Hanan versus Hunan. Just to be just be >> Cuz they're different. >> Sure. Fair. Totally enough. And um the paper that we covered last year >> Yes. >> 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

48:52these guys use synthesis of bulk hexagonal diamond and these guys are just like >> Bulk hexagonal diamond. >> Right? Okay. Also in nature. >> Yes. >> Now, this new paper >> Mhm. >> does not cite that older one from last year. >> No. >> Okay. I thought that was pretty hilarious. Because the reviewer comments in reviewer two actually does acknowledge this that a recent paper has come out >> Yeah. >> 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?

49:33>> But what that also tells me is that these guys lie 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? And in they were in the process of revision, which means they could have easily snuck in that >> Yep. >> that, but they didn't. >> Yep. >> Okay, I think already that's hilarious. Okay, there's clearly something >> didn't sample your your your chord from your 1967 hit. No, no, no, no, no. >> Yeah, yeah. And that same that same group um from the Shanghai University

50:14also did another paper in February. >> Mhm. >> 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 >> Right. >> no mention of even this paper. >> This this this is >> Like this is some beef, dude. >> is this is what beef looks like in the in the research community. >> something, right? So

Nature’s news coverage and the quote war

50:41um so I I wanted to dig a little bit deeper. So, nature has a news article about this, right? >> Where they talk about this they 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? So, what what's going on? So, I'm just going to read a little bit snippet of that of that news article, right? First of all, we we see um Shaoner who's the the reviewer number one. >> He gives a brief expose about like he says that the pattern of the diffraction peaks that are obtained very closely mimic that of hexagonal diamond and to

51:22demonstrate 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 he you know true to his 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. >> Like, you know, like 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 would they get a quote from those

52:04authors >> Oh, no. >> from the from the from last year's paper. And that guy, Houquang 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 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 There It's effectively they're saying I can't believe a reproduction paper >> Yeah, right. >> also got into Nature. >> Right. >> So, something happened, bro. Like, something happened with these two groups. >> And um Schauer

52:45>> Yes. >> who's the reviewer number one, >> Yeah. >> he did a minor clapback. >> Yeah, 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. >> Mhm. >> So, he's saying this paper has a definitive like hexagonal diamond X-ray diffraction pattern. >> That perhaps the other one didn't. >> Right. >> But I just this whole saga is hilarious to me. >> And and you actually brought this up when we did episode five where you you said, "I think there might be another team that is working on this within >> within China.

53:25>> within China, but the this these guys got out first. >> Yeah. >> Um and you had literally like it was I wish I will try to see if we can do a like a our our our throwback thing here because your statement on that episode is almost literally exactly >> out it was this. It was this team. It was the 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. Uh yeah, you know. >> Because because I think the point is like this is this is um it is a 50-plus-year-old >> Yeah. >> um unsolved problem. >> Mhm. So the prestige and the street cred

54:06and yada yada that you'll get from it for being first. >> Yeah. >> Uh matters. >> Yes. >> A lot. >> Yes. >> Especially in the material science cuz this resolves the simulation. Uh like

Why this matters for Chinese materials science

54:17people who are pooh-poohing oh the sims are wrong. >> Mhm. >> Uh 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 with fundamental material science research because they're having internal beef. >> Right. >> Right. Okay? >> Yeah. 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

55:00they are now, right? >> Yep. >> Where 20 years ago this kind of competition was unheard of. >> Right. >> And now and now we're we're at this stage. >> It it is I this >> 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. 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. >> And and this is not coming out of the South China Morning Post or you know an outlet that you can perceive to have geopolitical reason to frame it one way or another. Um And also the material science

55:40implications of this, as you brought up at the beginning, >> Yeah. >> from industrial application, etc. Obviously, there's a scaling issue. >> Yeah. >> Yada yada yada. >> Yeah, yeah, yeah. >> All this normal stuff we caveat. Regardless, um hugely, hugely impactful. Um and and I think sort of uh we'll see how the cuz we were we've This is now 6 7 months later >> Mhm. >> from our first coverage. >> Um we'll see how the story progresses,

What still needs to happen next — scaling and industrial use

56:06but this seems to be a little bit of the closing of the book on a couple of the aspects that we talked >> I think I mean, there's two there's two big research groups that have shown that this thing can work. >> Right. >> 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. >> industrially, right? >> But it works. >> Yeah. >> And we can do it. >> Mhm. >> Um great story again out of um out of Nature on March 4th, Zhongzhou, Nanjing, and uh uh Hanan universities in China, a follow-up to our episode 5. Um if you liked this episode, if you like

56:48again 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, uh 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 DeBeers "Diamonds are forever"? >> Mhm. >> Some diamonds >> Yeah. >> marketing. >> Yeah. >> Some not diamonds are hexagonal, but

Comment prompt — rebranding diamonds

57:18something. >> Something, yeah. Uh come up with your best tagline. >> Best tagline, cuz we need a rebrand for diamonds now because it's technically a different thing. >> Yeah. >> There's two types. >> There's two types. >> Yeah. >> Uh two types. I am your host Les Narie, I joined as always by my co-host and our resident PhD Krishna Choudhary. We appreciate you all joining us on this journey and we will see you later this week.