Proving what happens at the atomic interface

55:00lack of a better term. >> Exactly. Exactly. And Professor Joshua Wang, who was the principal investigator, he described this interface interaction between the tungsten and the graphine as oil and water. It's just like They're just not going to mix. Right. Makes sense. >> This is so good. >> It's it's it's pretty cool, right? So, now let's um you know, to get into a paper in science, >> you can't just have a cartoon. >> Yeah. [laughter] >> Right. That that's for me. >> But but uh in order to p in order to publish in science and convince your competitors that this is legit and all that other kind of stuff, you need actual analytical verification. So, let's go to the first analytical verification. This is high resolution trans transmission electron microscopy,

55:42electron microscopes. We've covered this a lot. Instead of light, we're using high energy electrons to really get down to um you know tiny tiny nanometer level resolution. On the top is a traditional memeister. Okay. You can see after after like not a lot of time the curves collapse. Yeah. >> Right. after just like 2,000 seconds, which is like less than an hour. Um, there's no memor. >> It's the slope of uh a mammoth. >> Yeah. Yeah. Yeah. Exactly. >> Straight down. >> Yeah. Yeah. Chair 36, [laughter] I believe. Correct me in the comments. I never go on those chairs. So, that'll be you lunatics. But on the right hand side

56:24is the transmission electron microscopes. And you can see at high temperature, you see this like mushroom cloud that's forming on the right hand side. >> That's the platinum and the tungsten meeting up. M and so instead of sort of maintaining the same like substrate texture or orientation this there's just this disturbance in the force. >> Exactly. There's visually see it. >> Yeah. And you can see the halfnam oxide in the middle right the meat but like the platinum is just like going through. Why would you why would you go through the half oxide right on the bottom >> is our new meister with graphine. And there you can see even at high temperature, even after all of that cycling, >> the graphine layer >> the graphine layer is inert. The

57:06tungsten layer is inert. Nothing is happening. This is incredible. There's no chemistry happening. >> And it's it's also so verifiable. >> Yeah. You can literally look at it under the microscope and I can see >> and you can see that it's happening. >> That stupid analogy is like imagine you have a BLT sandwich from a deli and they put the the thumb the the the toothpick through it. In the first case, it's like, you know, the toothpick through where you can see it disturbs the nice layers you have of your tomato, bacon, lettuce. Yeah. >> And it looks like a very nice undisturbed. But but the point here is the the high resolution imagery that is able to validate that this graphine based meister actually sustains at high

57:48temperature is undeniable. >> Yeah. Yeah. Yeah. It's like now you don't need a cartoon. This is the thing that the cartoon is literally what it is. Right. right? Like you're just seeing it. I can see it. Um here's another way to see it. You can use energy dispersive X-ray spectroscopy. The idea here is that um like so during in the previous photo we we had transmission electron microscopy. So you're like sending these high energy electron beams, right? That strike the sample. Now when those electrons strike the sample, it can transfer energy and violently kick electrons out. And when the electrons come back, they're going to release X-rays, right? And if I monitor the X-rays during that electron

58:30microscopy because every atom is unique, the X-ray signature is going to be unique. Like in the transmission electron microscopy, people could be like, oh, like there's some weird thing happening. How do you know that's tungsten? How do you know that's plat platinum? Right? It's just a gray image. Well, now we can tell that it is in fact tungsten that is leaking through because only a certain energy comes from tungsten. And we're seeing that energy spike. >> Yeah. >> In the old memorister, but in the new memor there's no tungsten spike. >> Tungsten spike. >> The W, by the way, for those watching, W is the chemical symbol for tungsten >> because of Latin. And it so it's

59:12interesting because I I think part of this is like you you're doing both of these things almost simultaneously because because the the electron microscopy is triggering an event that you track with the X-ray spectroscopy. And so you're getting both the visual and the the signature. >> Yeah. Exactly. >> That allows you to identify the uh the composition of what you're looking at and can see visually. >> Exactly. And so if you look in the platinum electrode, there is tungsten there. If you look in the graphine, there's no tungsten, >> right? >> Undeniable. >> Um, there were also some calculations that were done from first principles. >> So, um, you've got electron densities with density functional theory. Density functional theory is something that we

59:52covered in our America 250 episode. It won the Nobel Prize. This is what I mean by density functional theory. Okay? It's like you don't have to worry about every single electron. You can just be like the electron clouds are like a potential. What happens when a tungsten atom goes through? Does it bind or not? On the right hand side is what platinum looks like. These giant sort of honeycomb structures where the dorbital, which is the stuff that um these are these large dorbitals of metals, right? They're extremely large. The tungsten is fine kind of just binding to one of these dorbitals because they're so they're so big, right? And there's a lot

1:00:35of vacant spots where the tungsten can go and bind. On the left hand side is graphine. Pristine hexagonal structure. Um I think it's only just like sp2 binding or maybe sp3. I I forget my chemistry. But in any case, the the bond lengths in between the carbons are smaller. The graphine electron clouds are a lot smaller. So the tungsten has nowhere to go. >> It's incredible. >> Right? There's the You see the fat little like pimple? Yes. >> That's the tungsten atom and it's trying to find somewhere to bind >> and it can't. >> Yeah. It's like the grill on like your microphone or a speaker cover. Yeah.

1:01:15>> Uh versus like you described like >> a bunch of donuts that got blend or like you know Hawaiian rolls that got that got baked together with no clear actual like structural like you know like a well-defined small structural positioning. Exactly. Um, and it's part of your point that the the the smaller size of the electron cloud is a material aspect of why >> the because the tungsten is just not small enough to >> Yeah. Yeah. The tungsten is not small enough. The smaller size also means that you need a higher energy to get in there. >> That makes sense, right? And um and and all of the stuff is is taken. >> Yes. >> Right. With with graphine because of that hexagonal structure, it's just carbon on carbon on carbon. All of the

1:01:56carbon atoms are happy. They don't want anything else. >> They don't want anything. >> Right. Yeah, it all. Oh, that's so good. >> So, it's all coming together. And the final thing that I want to talk about is um the nudged elastic band. >> Uh this isn't the final thing, but I just go go I'm going through their figures because they're just so cool. Okay, so [clears throat] on the left hand side, again, that's the old Memorister. Um, this is an activation energy diagram that shows if I want the tungsten to bind to my platinum, I need to [snorts] go over this hill and then and then there's like a valley on the other side where I'm bound to the platinum. The height of the hill is.3 electron volts. >> Mhm. [clears throat] >> And then the the there's a there's a

1:02:37nice valley where I can just like sit. On the right hand side is the same diagram but for graphine. The height of the hill is now 1 to two electron volts. And there's no nice valley, right? Like if I'm up there and I'm jiggling around, I'll just come right back. >> Yeah. >> To my original state. >> So again, same idea. It's really hard to bind to graphine. >> It's really good. >> Okay. >> Now, one thing that I was thinking about was there's kind of a paradox in my head, right? Like the high resistance state makes sense. high resistance meaning um the there's no oxygen vacancy highway