Possibly the Beginning of Quantum Well Superconductors

I think the new regular pressure room temperature superconducting work will prove to be the start of the field of quantum well superconductors. NOTE: The South Korean paper still needs to be replicated and confirmed. Extraordinary claims need a lot of verification and study. The work can be mistaken or wrong.

Other researcher are within days of replication or replication problems.

Meissner effect or bust. Day 1.

Made good progress on the list of to-dos. I’m doing this all after-hours, so it’s been a long day. Since we’re gated by the delivery of the PbO + Pb(SO4), which should be tomorrow, we’re working on infrastructure first. pic.twitter.com/CLHlL5DOul

— Andrew McCalip (@andrewmccalip) July 27, 2023

Getting the DAQ set up. Will do multi channel thermocouple probes in furnace to ensure best control. We verified 930°C with our small 6″x6″x6″ furnace. All data logged to Influx so we can verify ramp rates. pic.twitter.com/aXamVKXLJE

— Andrew McCalip (@andrewmccalip) July 27, 2023

Getting the DAQ set up. Will do multi channel thermocouple probes in furnace to ensure best control. We verified 930°C with our small 6″x6″x6″ furnace. All data logged to Influx so we can verify ramp rates. pic.twitter.com/aXamVKXLJE

— Andrew McCalip (@andrewmccalip) July 27, 2023

Meissner effect or bust: day 1.5

Unbelievable outpouring of support. The most positive trend I’ve ever seen on Twitter. It feels like the entire world is shouting, GO!

Sigma package arrived! First thermal synth (PbO + PbSO4) might start tonight.

Potential partnerships with… pic.twitter.com/rvglyHlKUl

— Andrew McCalip (@andrewmccalip) July 27, 2023

There is an assessment by PHD Chemist Derek Lowe at the journal Science.

Let’s look at what’s being claimed, and how strong the evidence seems to be. The authors describe a lead-based copper-doped material, LK-99, which is made by first preparing a well-characterized mineral (lanarkite, Pb2(SO4)O) from lead oxide and lead sulfate. Separately, copper phosphide (Cu3P), another well-characterized compound, is also freshly prepared from elemental copper and phosphorus. These two substances are ground together in a 1:1 ratio and the mixture is sealed in a vacuum-evacuated quartz tube and heated to 925C, forming LK-99, which is Pb10-xCux(PO4)6O, a dark polycrystalline material. The structure is very similar to lead apatite, a well-characterized phosphate mineral, but its crystallographic unit cell is slightly smaller due to the substitution of particular lead atoms in its lattice by copper ones.

The authors believe that the modified/strained structure of their material creates a large number of “quantum wells” between particular lead atoms and the adjacent oxygens of the phosphate groups bound to them, in effect making a two-dimensional “electron gas”. They propose that electron tunneling between these quantum wells, which are between 3.7 and 6.5 Ångstroms apart, is the superconducting mechanism. The authors are making a detailed mechanistic claim that is subject to experimental proof.

They demonstrate the behaviors that a superconductor should have, such as the Meissner effect (expulsion of a magnetic field), sudden resistivity changes at a critical temperature (bizarrely high though that is in this case), current-voltage (I-V) plots at different temperatures and under different magnetic field strengths, etc. If these data reproduce, the superconductivity of this material seems beyond doubt.

Comment from Joe Ecks, who has been working on superconductors at superconductors.org:

The resistance measurements they report, in the range of 10^-6 to 10^-9 Ω·cm, remind me of “ultra-conductors”. Ultra-conductors are polymers that have extremely low resistance – but NOT zero ohms. The critical current the Koreans report is also not typical of a true superconductor. They report a Jc of around 250 ma (1/4 amp) at room temperature. This is not compelling evidence of true RTSC.

My comment: The thin film does meet the superconductor resistance threshold. They need to do more work to perfect the bulk material. One possible work around later will be to stack layers of thin film. The low critical current means we need to find other materials that leverage quantum wells in a more robust way if the experiment and theories are correct.

Different Researchers With Allegations of Research Malfeasance

Ranga Dias is a different researcher who has nothing to do with the South Koreans and they have entirely different materials.

Nature – Evidence of near-ambient superconductivity in a N-doped lutetium hydride. Ranga P. Dias et al Ranga work requires diamond anvils for the pressure. Even his “near ambient superconductivity” is at 10,000 times regular pressure. 10 times more than the Marianas trench.

Nanjing University tried to make Ranga’s material but did not see the superconductivity.

Different American researchers were given some of the material made by Ranga’s lab and they confirmed the superconductivity. They published a preprint on arxiv.

Ranga had to withdraw a 2021 paper but did not admit any malfeasance.