# Room temperature superconductivity **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Tags:** science-math\ **Created:** [July 26, 2023, 8:52pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663 "2023-07-26T20:52:37Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 26, 2023, 8:52pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/1 "2023-07-26T20:52:37Z")
This paper started making the rounds yesterday: > **[The First Room-Temperature Ambient-Pressure Superconductor](https://arxiv.org/abs/2307.12008)** > > For the first time in the world, we succeeded in synthesizing the room-temperature superconductor ($T\_c \\ge 400$ K, 127$^\\circ$C) working at ambient pressure with a modified lead-apatite (LK-99) structure. The superconductivity of LK-99 is proved... With a bit more info here: > **[Superconductor Pb$\_{10-x}$Cu$\_x$(PO$\_4$)$\_6$O showing levitation at room...](https://arxiv.org/abs/2307.12037)** > > A material called LK-99, a modified-lead apatite crystal structure with the composition Pb$\_{10-x}$Cu$\_x$(PO$\_4$)$\_6$O ($0.9 In short, they claim to have a room-temperature superconductor that works at ambient pressure (instead of only under a diamond anvil or the like). Or rather, they claim to have a superconductor that works all the way up to 127 C! It’s a rather remarkable claim, and there is obviously reason to be extremely skeptical. Derek Lowe goes into a bit here: [https://www.science.org/content/blog-post/breaking-superconductor-news](https://www.science.org/content/blog-post/breaking-superconductor-news) The papers don’t appear to be complete bunk, though, so the attitude should probably be one of skepticism rather than dismissal. One nice thing about it is that the material is easy to synthesize, and the claims easy to verify. This isn’t something that requires specialized equipment that only exists in one lab, or where the effect is so tiny that you never really know whether it’s noise or not. For instance, they demonstrate levitation over a magnet, which is a property of all superconductors–and trivial to see if it works or not. So, don’t get your hopes up yet. And even if it can be reproduced, it is far from being a commercially viable material. But it will be interesting to see the followup, which should be fairly quick. ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 26, 2023, 9:00pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/2 "2023-07-26T21:00:07Z")
My initial reaction (to some knowledgeable colleagues): > Damn! After reading the first page of the Introduction, I was expecting to see room temperature SQUID data. Turns out they just used a conventional SQUID to measure magnetization. > > I’m not sure any of the measurements shown on page 3 convince me. However, they do conclusively state: > > “LK-99 is a gray-black color, as shown in Figure 3(b). It is the superconductor with the same color as typical superconductors.” > > I’m not sure I’m convinced by any of the figures, especially since they don’t describe the experimental set up used for most of the figures. I am heartened that my speculation that they might be able to use atomic substitution in the lattice to produce the same effects as applying external pressure is being followed through on. The “conclusively state” section is sarcastic, in case you didn’t catch it. FWIW, there is a video out there purporting to be levitation of this material. > **[A paper & movie will be released that states that \`\` a substance that...](https://gigazine.net/gsc_news/en/20230726-room-temperature-superconductor/)** > > The news blog specialized in Japanese culture, odd news, gadgets and all other funny stuffs. Updated everyday. On the other hand, this group apparently had to withdraw claims of room temperature superconductivity made in 2020. Wait and see is definitely advised. ETA: it is a little known fact that the discovery of YBCO was prompted by Paul Chu’s work on superconductivity under pressure and his thoughts that such pressure could be accomplished by lattice substitutions of larger atoms. ---
**Author:** ![Maserschmidt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/maserschmidt/32/18829_2.png) [@Maserschmidt](https://boards.straightdope.com/u/Maserschmidt)\ **Post date:** [July 26, 2023, 9:09pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/3 "2023-07-26T21:09:07Z")
> [@peccavi](#): > > On the other hand, this group apparently had to withdraw claims of room temperature superconductivity made in 2020. [https://twitter.com/alexkaplan0/status/1684088656720437249?s=61&t=7zPHcBzjb1UW-wh6DrDc3g](https://twitter.com/alexkaplan0/status/1684088656720437249?s=61&t=7zPHcBzjb1UW-wh6DrDc3g) The whole thread is interesting, I just posted that tweet in response…if you (generic SDMB you) work your way upstream you can read some ways it was be hugely beneficial. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 26, 2023, 9:11pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/4 "2023-07-26T21:11:04Z")
> [@peccavi](#): > > such pressure could be accomplished by lattice substitutions of larger atoms. Is there any intuitive explanation for why pressure encourages superconductivity? Seems clear that it plays a significant role. Not that anything about the theory of superconductivity is really intuitive, but I vaguely get Cooper pairs, at least. The video, for those that don’t want to click through: [![](https://img.youtube.com/vi/aw5sw5TDihU/hqdefault.jpg "「超電導体の磁気浮上を室温かつ常圧で確認した」とされるムービー【LK-99】") ](https://www.youtube.com/watch?v=aw5sw5TDihU) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 26, 2023, 9:22pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/5 "2023-07-26T21:22:47Z")
I’ll just note that that video does not show levitation: A corner of the chip is always in contact with the base. I mention this because, while stable levitation is a property of superconductors, it’s really easy to get any old ordinary magnet to almost-levitate with only a tiny bit of direct contact to stabilize it. Which makes me pessimistic: Surely, if this material were what they claim it is, it wouldn’t have been hard to get actual levitation. ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 26, 2023, 9:24pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/6 "2023-07-26T21:24:31Z")
No, that paper from Rochester was from 2021. The Gigazine page refers to a 2020 paper from this group (but I haven’t found any other cites) > [@Dr.Strangelove](#): > > Is there any intuitive explanation for why pressure encourages superconductivity? Seems clear that it plays a significant role. Not that anything about the theory of superconductivity is really intuitive, but I vaguely get Cooper pairs, at least. Since BCS superconductors depend inherently on electron-lattice interactions, its intuitive that changing the lattice dynamics would affect superconductivity. However, my understanding is there is no consensus (still) on the theoretical underpinnings of HTS (even YBCO). I’m not a theorist, though. ---
**Author:** ![Maserschmidt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/maserschmidt/32/18829_2.png) [@Maserschmidt](https://boards.straightdope.com/u/Maserschmidt)\ **Post date:** [July 26, 2023, 9:27pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/7 "2023-07-26T21:27:08Z")
Ah, in the tweet they say 2020, but it sounds like there are multiple studies. ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 26, 2023, 9:28pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/8 "2023-07-26T21:28:13Z")
Here’s a Nature News report from today: [‘A very disturbing picture’: another retraction imminent for controversial physicist (nature.com)](https://www.nature.com/articles/d41586-023-02401-2) ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 26, 2023, 9:39pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/9 "2023-07-26T21:39:15Z")
> [@Maserschmidt](#): > > Ah, in the tweet they say 2020, but it sounds like there are multiple studies. In rereading the Gigazine page (now there’s a highly respected scientific journal cite!), it is unclear whther they are stating that this group withdrew their claims or some other, earlier group withdrew claims. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 26, 2023, 9:41pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/10 "2023-07-26T21:41:46Z")
> [@peccavi](#): > > In rereading the Gigazine page (now there’s a highly respected scientific journal cite!), it is unclear whther they are stating that this group withdrew their claims or some other, earlier group withdrew claims. Pretty sure they’re just referring to the University of Rochester group. If you click through the link, it goes to this page: > **[100年以上も低温下の現象とされた「超伝導」を室温で発生させることに成功](https://gigazine.net/news/20201015-room-temperature-superconductivity-first-time/)** > > By Argonne National Laboratory And this one: > **[夢の「室温超伝導」の論文はいかにして白紙になったのか](https://gigazine.net/news/20220928-room-temperature-superconductivity-study-retracted/)** > > 2022年9月26日に、科学誌・Natureが室温超伝導に関する2020年の論文を撤回しました。実現すれば浮かぶ自動車やリニアモーターカー、小型で安価な量子コンピューターなどさまざまな新技術に発展し、人類に産業革命をも超えるインパクトをもたらすと期待されていた室温超伝導の研究が否定された経緯について、アメリカ科学振興協会がまとめています。 It’s all machine translated, so I’m sure some of the nuance was lost. Or maybe not there in the first place. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 26, 2023, 9:51pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/11 "2023-07-26T21:51:32Z")
> [@Chronos](#): > > Surely, if this material were what they claim it is, it wouldn’t have been hard to get actual levitation. From what I’ve read, it’s not uncommon to have this partial levitation effect in superconductors. Sure they could have faked it by embedding a tiny magnet in one corner of the sample, but they could have faked lots of other things, too. Well, either it’ll be reproduced or not. It doesn’t seem like this will end up like cold fusion or whatever since the effects are so dramatic. ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 26, 2023, 10:25pm UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/12 "2023-07-26T22:25:22Z")
> [@Dr.Strangelove](#): > > From what I’ve read, it’s not uncommon to have this partial levitation effect in superconductors. Sure they could have faked it by embedding a tiny magnet in one corner of the sample, but they could have faked lots of other things, too. It’s hard to get a feel for the video. On the one hand, there doesn’t seem to be any condensation or other indications of cooling of the superconductor chip. On the other hand, at one point the chip falls flat on the magnet, then pops back up, which is strange. However, my experience playing with levitation is always with the superconductor cooled as the base and the smaller magnet levitating above it. The usual indication that you aren’t dealing with two magnets is that when you poke the magnet it resists displacement because of flux pinning in the superconductor (in fact, once you have levitation achieved, you can flip the superconductor over to show the magnet “hanging” from the superconductor instead of “floating”). With magnets, any levitation tends to be unstable, where any disturbance causes flying apart or sticking together. My first question when someone said there was a video was “Did they poke it?” But I have no intuition when it comes to a small superconductor levitating above a large magnetic surface. Is the behavior shown in the video consistent with a sample where the superconductivity is not uniform? ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 27, 2023, 12:53am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/13 "2023-07-27T00:53:56Z")
> [@peccavi](#): > > Is the behavior shown in the video consistent with a sample where the superconductivity is not uniform? Seems reasonable enough. If the sample were impure or not consistently structured, such that only one part was actually superconductive, I’d think you’d get that kind of behavior. But I agree, it’s hard to judge. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2023, 1:10am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/14 "2023-07-27T01:10:50Z")
> [@peccavi](#): > > With magnets, any levitation tends to be unstable, where any disturbance causes flying apart or sticking together. In fact, there’s a theorem that any static arrangement of magnetic dipoles, electric charges, and/or gravitating masses is unstable. It’s not even difficult to prove. (the catch, of course, that allows for superconductive levitation, as well as the normal cohesion of the atoms in matter, is that the charges/magnetic poles in those situations aren’t static.) ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 27, 2023, 1:16am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/15 "2023-07-27T01:16:57Z")
Earnshaw’s theorem makes a whole lot of assumptions. The static configuration being a big one. But diamagnetic levitation is also possible: [![](https://www.seattleu.edu/media/college-of-science-and-engineering/images/departments/physics/physicsdemos/electricityandmagnetism/diam-lev-side.jpg) ](https://www.seattleu.edu/media/college-of-science-and-engineering/images/departments/physics/physicsdemos/electricityandmagnetism/diam-lev-side.jpg) ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [July 27, 2023, 1:31am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/16 "2023-07-27T01:31:51Z")
> [@Chronos](#): > > the catch, of course, that allows for superconductive levitation, as well as the normal cohesion of the atoms in matter, is that the charges/magnetic poles in those situations aren’t static. I don’t think that’s quite correct. Penetration and pinning of flux is necessary for stable levitation. If you try levitation using a Type I superconductor (most elemental superconductors like Pb or Al are Type I, and most require liquid He temperatures or lower), the magnet flux from the magnet does not penetrate while the exclusion of flux (Meissner effect) still creates a force on the magnet so the magnet is unstable in position and will “slide” off. Type II superconductors exclude flux completely below a certain field strength, but above that limit, instead of returning to the normal state like Type I, they create spots of penetration, called fluxoids. These fluxoids are arranged in a regular lattice on the superconductor and it is energetically unfavorable to move them from where they are on the superconductor (pinning). Of course, there is also flux penetration through grain boundaries in both Type I and II polycrystalline material, but it is trickier to engineer flux pinning at grain boundaries in Type I superconductors, so they are still very unstable in levitation. However, because of the very low transition temperature of Type I superconductors, a simple tabletop demonstration is out of the question, so you’re not going to find many videos of people trying levitation using lead (Tc ~7 Kelvin). ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [July 27, 2023, 1:50am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/17 "2023-07-27T01:50:54Z")
From what I’ve heard, this was made in a fairly straightforward way from materials that are widely available. So it should be confirmed or denied fairly quickly. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2023, 2:03am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/18 "2023-07-27T02:03:42Z")
> [@peccavi](#): > > I don’t think that’s quite correct. Penetration and pinning of flux is necessary for stable levitation. I didn’t say that dynamic charges were a sufficient condition for stability, only necessary. Obviously it’s possible to create dynamic systems that are still unstable (in fact, magnetostatics, when you get right down to it, is just a special case of electrodynamics). > [@puzzlegal](#): > > From what I’ve heard, this was made in a fairly straightforward way from materials that are widely available. So it should be confirmed or denied fairly quickly. On the other hand, the process (if true) apparently isn’t completely reliable, given that they’re claiming that only parts of their specimen are superconducting. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [July 27, 2023, 2:08am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/19 "2023-07-27T02:08:51Z")
My impression is that this is easy enough that a lot of labs will be trying to reproduce it. This isn’t an area I know anything about, but my friends have been talking about it. Anyway, I guess we’ll see. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 27, 2023, 2:18am UTC](https://boards.straightdope.com/t/room-temperature-superconductivity/987663/20 "2023-07-27T02:18:25Z")
If true, it may be very sensitive to the level of dopants in the sample, etc. And if not well controlled, it could be that for a large sample, there’s variation in the structure and it’s only superconducting for the part where the levels are just right. Not too different than early semiconductor work, where it took a long time to get consistent results. But even if it’s inconsistent at first, they should be able to get working samples with enough tries. If the effect is real, that is. [Next page](https://boards.straightdope.com/t/room-temperature-superconductivity/987663.md?page=2)