Hope, skepticism around LK-99, the Korean scientists’ room temperature superconducting material

The global scientific community has greeted the development of a room temperature superconducting material by a group of Korean scientists with both hope and skepticism. 

The development of such a superconducting alloy, christened LK-99, if proven to be what it is claimed, has the potential to revolutionise the world “in ways you cannot imagine”, says Prof Deepshikha Jaiswal Nagar, Associate Professor (Physics), Indian Institute of Science Education and Research, Thiruvananthapuram, and also fetch the Korean scientists a physics Nobel Prize. 

Sukbae Lee, Ji-Hoon Kim (from whom comes “LK”) and Young-Wan Kwon, reported through a scientific paper in July that “for the first time in the world, we succeeded in synthesising the room temperature superconductor working at ambient pressure, with a modified lead-apatite (LK-99) structure”.

The critical temperatures

A superconducting material lets current pass through it without offering any resistance, which means no “transmission and distribution losses”, because ‘resistance’ causes a part of the current to be converted, wastefully, into heat. 

Good conductors of electricity become superconductors at a certain “critical” temperature, which is extremely low. For example, copper becomes superconducting at near ‘absolute zero’ temperature, or nearly minus 273 degrees Celsius.  

For well over a century, scientists have been trying to develop a material that does not require to be so cold to be superconducting – preferably, super conduct at room temperature.  

Finding such a material means that power transmission, motors, generators, electronics become highly efficient and even transport (super-fast maglev trains) becomes possible. Compact generators mean that offshore wind turbines can be small and hence cost-effective. 

That is why when Lee, Kim and Kwon put out their paper, the scientific community sat up in disbelief. 

At least two groups of scientists prepared LK-99 in their labs using the recipe provided by the Koreans and tried to see for themselves if it is really superconducting. Both failed. 

One group was Indian, led by Dr Veerpal Awana of the National Physical Laboratories (NPL), New Delhi and the other was a Chinese group. 

Neither got the same results as the Koreans did, but nevertheless Dr Awana says he is “100 per cent” optimistic that the LK-99 will lead on to a truly superconducting material. “This compound (LK-99) is not yet proven but is very promising,” Dr Awana told businessline. 

Prof Deepshikha Jaiswal Nagar says that the reason why the Koreans got superconductivity but the Indians and the Chinese didn’t, could have something to do with where copper plugs into lead in LK-99 – at ‘site-1’ or ‘site-2’. She conjectures that the LK-99 made by the Indian and Chinese had the copper hooked at site-2, whereas the Koreans got it at site-1.  

Two properties 

A superconducting material should have two properties. It must offer zero resistance to current; it must display diamagnetism—it should repel magnetic forces.

LK-99 does not appear to have shown diamagnetism. Prof. Dilip Pal, Department of Physics, IIT Guwahati,notes that for LK-99 “there is no data showing perfect diamagnetism.” He further notes, “It does not show ZERO resistance. It only shows that there is sharp drop in the resistance above room temperature.”

“As scientists, we have to be cautious, because generally all preliminary measurements are always sloppy,” Dr Pal told businessline.

Dr Yadav, Associate Professor, IIT-Mandi, observes that “the clear signatures of superconductivity are still elusive. Nonetheless, it opens the field for searching for room temperature compounds in this class of materials.” 

In an email to businessline, Dr Yadav said: “The transitions in resistivity and low-field magnetization data are not very clean, which raises doubt on the reproducibility of their results. Although there is one report from China that also claims to show magnetic levitation, confirmation from other labs with clean experimental data is required, before the wide acceptance of room temperature superconductivity in LK99 compounds. Nonetheless, it opens the field for searching for room temperature compounds in this class of materials.” 

Dr Awana is working on one such compound, using zinc in place of copper in LK-99. “The sample is in the furnace,” he told businessline. 

Dr. Ajay Soni, Associate Professor, School of Physical Sciences, IIT Mandi, says that while room temperature superconductivity “remains a mystery”, the critical temperature of 127 degrees C “is opening a fresh debate on a new research area.”

In an email to businessline, Dr Soni said: “Recently, many research groups have come up with new materials and novel explanations for the existence of room temperature superconductivity.  If the discovery is established, then it will definitely change the electronic market and lifestyle on earth overall.  Though there may be some finite possibilities, I feel it is still at an early stage. The results in the arxiv article are preliminary and offer questionable hints. Nevertheless, the scientific community has a lot of patience, we need to wait and watch for more experiments and reproducible results from other groups as well to validate the science and then to establish the claims. Similar claims were also made a few years ago on different sets of materials, and we are still waiting for a reproducible way to prepare these materials. Thus, lets get more data sets and demonstrations” 

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