The magnetization plots at page top show Meissner transitions of about 8 milligauss for TmYO3 and 4-5 milligauss for Tm2YO4.5. The below plot of Tm3YO6, which appeared as a minority phase in the other two formulations, shifts about 3-4 milligauss. The transition temperatures (Tc) were 117K, 130K and 140K respectively. Though the volume fraction is low, the evidence for superconductivity was unambiguous, appearing in over a half-dozen tests of each material. Lines have been drawn through the noise to approximate the average of the data points.
The chemical precursors were pelletized at 60,000 PSI and sintered for 10 hours at 880C. They were then annealed for 10+ hours at 500C in flowing O2. Temperature was determined using an Omega type "T" thermocouple and precision OP77 DC amplifier. The magnetometer employed twin Honeywell SS94A1F Hall-effect sensors with a tandem sensitivity of 50 mv/Gauss. Prior research by ORNL and the University of Rome has determined that high-temperature superconductivity "arises from the oxygen ions". See: "High-Tc Superconductivity at the Interface between the CaCuO2 and SrTiO3 Insulating Oxides" Phys. Rev. Lett. 115, 147001 – Published 28 September 2015. dx.doi.org/10.1103/PhysRevLett.115.147001
RESEARCH NOTES: These oxides can be strongly hygroscopic. All tests should be performed immediately after annealing.
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E. Joe Eck
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