High Temperature Superconductivity.
NAVAL RESEARCH LAB WASHINGTON DC
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After the initial discovery of superconductivity over 30K in the La2-XBaXCuO4 system several groups confirmed the result both resistively and magnetically flux expulsion. Ultimately, transitions were observed in the analagous compounds with Ba replaced with Ca7 and Sr7,8 for 0.1 less than or equal to X and less than or equal to 0.3 with the highest Tcs above 40K. Our samples were prepared from regent grade powders of La2O3, BaCo3, SrCO3, CaCO3, PbO2, and CuO. The powders were mixed inappropriate ratios and calcined in air between 1000C and 1100C for 12 hours. The resulting materials were reground, pressed into small disks nominally 1cm. diameter by 2mm. height and sintered in air at 1000C-1100C for 12h. The calcined powders and sintered pellets were x-rayed following each process to ensure that the proper phase was present. Keywords Calcium, Strontium, Lanthanum, Barium, Copper, Lead.
- Electricity and Magnetism