Scientists strangely unable to follow recipe for holy grail room-temp superconductor

Race to replicate LK-99, and the process used to create it, hits plenty of hurdles

Scientists are struggling to verify South Korean eggheads' claim to have synthesized a material that exhibits superconductivity at room temperature and normal pressure.

Late last month, researchers at the Quantum Energy Research Centre in Seoul, along with others, published a paper claiming that a material they called LK-99 is the long-sought-after superconductor that works at room temperature and ambient atmospheric pressure. Most superconducting materials found to date require very cold temperatures and high pressures before they display the vastly desirable quality of hugely reduced electrical resistance.

If LK-99 is indeed a superconductor that works in everyday conditions, it would likely revolutionize industry by, for example, making it possible to eliminate losses due to electrical resistance in power grids.

LK-99, also known as copper-doped lead-apatite, was shown in videos partially levitating above a magnet, supposedly due to a property of superconductors known as the Meissner effect. As The Register reported at the time, other scientists expressed skepticism, and said that while the paper was interesting, the claims it contained did not appear to be entirely convincing.

Last week, the Korean Society of Superconductivity and Cryogenics (KSSC) claimed to have invalidated the original research results regarding the putative room-temperature superconductor.

According to newspaper Korea JoongAng Daily, the KSSC said that the data from the studies published by the Quantum Energy Research Centre indicated different physical properties from that of a typical superconducting material. In addition, the behavior of the levitating specimen shown in footage could be reproduced with other materials that are not superconductive.

A number of teams around the world have tried to replicate the findings of the paper’s authors, though it seems that none of these attempts has so far been peer-reviewed. The LK-99 Wikipedia page tracks some of those efforts and points to publications on efforts on the open-access repository Arxiv.

Of the attempts listed, a few have reported partial success, for example by claiming to have successfully synthesized LK-99 and observed diamagnetism - the phenomenon of materials being repelled by a magnetic field. But other studies have reported failure, stating that they observed no diamagnetism or that the synthesized LK-99 did not exhibit zero electrical resistance.

According to the New Scientist, the Korean researchers that created LK-99 reported zero resistivity for temperatures ranging from 30°C (86°F) to 127°C (261°F), though a team at the University of Nanjing in China attempting to replicate their experiments found that resistance only dropped to zero below -163°C (-261°F).

Some of the differences in the reported findings may be due to difficulties in replicating the exact material that the Korean researchers used for their experiments.

One of those attempting to reproduce LK-99 is Andrew McCalip, an engineer at Varda Space Industries in California, who expressed concern that the paper describing LK-99 is unhelpfully vague on the processes used to create the purported superconductor.

McCalip said that he was looking for answers to the level of purity required for the precursor materials, the temperature ramp-up and ramp-down rates for the reactions involved in created LK-99, whether any thermal annealing steps were involved, and how repeatable their prescribed recipe is, among other details.

Simon Clarke, a professor of chemistry at the University of Oxford, has also expressed skepticism, stating that the Korean researchers did not synthesize a pure sample of LK-99 - which is made by introducing a small amount of copper to the material - and the types of analysis required to verify the structure of any newly discovered material were not carried out. Reliably measuring resistance requires a pure sample, he said.

So the jury is still out on whether the Korean researchers have made history in mixing up the first room temperature superconductor, or whether they will join the long list of such claims that have ultimately failed to stand up to peer-review and critical scrutiny.

Who wrote this?

And that's not to mention the drama over the release of the papers. There are in fact two LK-99 papers, the above-linked one that gives a summary of the material's properties, and a second one that goes into detail on the construction and make-up of the material.

The first lists Sukbae Lee, Ji-Hoon Kim, and Young-Wan Kwon as authors, and was submitted to Arxiv as a pre-print paper by Kwon on July 22. The second lists Sukbae Lee, Jihoon Kim, Hyun-Tak Kim, Sungyeon Im, SooMin An, and Keun Ho Auh; it was submitted just hours later that same July day by Hyun-Tak Kim. The second paper does not formally credit Kwon as an author.

It is claimed the first paper was submitted prematurely, and that the scientists were waiting for a formal peer review to complete before going public.

The majority of the authors are linked to the Quantum Energy Research Centre, founded by Korea University academics, while Kwon is just linked to that Seoul university, we note. It's reported that Kwon left the research center as CTO just a few months prior to the LK-99 papers being shared. Sukbae Lee and Ji-Hoon Kim are both executives at the center.

And patent applications have been filed regarding LK-99, which is named after Sukbae Lee and Ji-Hoon Kim and 1999, the year they apparently came up with the material with Tong-Shik Choi at Korea University. A patent for LK-99 published in March this year lists Lee, Kim, and Kwon as inventors; an earlier application listed Lee and Kim. ®

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