Indication for high Tc superconductivity at 373 K with h_eff/h= 2

Some time ago I learned about a claim of Ivan Kostadinov about superconductivity at temperature of 373 K (100 C). There is also claims by E. Joe Eck about superconductivity: the latest at 400 K. I am not enough experimentalist to be able to decide whether to take the claims seriously or not.

The article of Kostadinov provides a detailed support for the claim. Evidence for diamagnetism (induced magnetization tends to reduce the external magnetic field inside superconductor) is represented: at 242 transition reducing the magnitude of negative susceptibility but keeping it negative takes place. Evidence for gap energy of 15 mV was found at 300 K temperature: this energy is same as thermal energy T/2= 1.5 eV at room temperature. Tape tests passing 125 A through superconducting tape supported very low resistance (for Copper tape started burning after about 5 seconds).

I-V curves at 300 K are shown to exhibit Shapiro steps with radiation frequency in the range [5 GHz, 21 THz]. Already Josephson discovered what - perhaps not so surprisingly - is known as Josephson effect. As one drives super-conductor with an alternating current, the voltage remain constant at certain values. The difference of voltage values between subsequent jumps are given by Shapiro step Δ V= h f/Ze. The interpretation is that voltage suffers a kind of phase locking at these frequencies and alternating current becomes Josephson current with Josephson frequency f= ZeV/h, which is integer multiple of the frequency of the current.

This actually gives a very nice test for h_eff=n× h hypothesis: Shapiro step Δ V should be scaled up by h_eff/h=n. The obvious question is whether this occurs in the recent case or whether n=1 explains the findings.

The data represented by Figs. 12, 13,14 of the artcle suggest n=2 for Z=2. The alternative explanation would be that the step is for some reason Δ V= 2hf/Ze corresponding to second harmonic or that the charge of charge carrier is Z=1. (bosonic ion). I have not been able to find any error in my calculation.

1. Fig 12 shows I-V curve at room temperature T=300 K. Shapiro step is now 45 mV. This would correspond to frequency f= ZeΔ V/h=11.6 THz. The figure text tells that the frequency is f_R=21.762 THz giving f_R/f ≈ 1.87. This would suggest h_eff/h=n ≈ f_R/f≈ 2.
2. Fig. 13 shows another at 300 K. Now Shapiro step is 4.0 mV and corresponds to a frequency 1.24 THz. This would give f_R/f≈ 1.95 giving h_eff/h=2.
3. Fig. 14 shows I-V curve with single Shapiro step equal to about .12 mV. The frequency should be 2.97 GHz whereas the reported frequency is 5.803 GHz. This gives f_R/f≈ 1.95 giving n=2.

For background see the chapter Quantum Model for Bio-Superconductivity: II.