The chemical precursors were pelletized at 60,000 PSI and pre-sintered for 24 hours at 715C. The pellet was then sintered for 10 hours at 880C and 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.
In March 2015, Superconductors.ORG announces the discovery of two new superconductors with transition temperatures (Tc) more than 100 degrees above room-temperature. Sn9SbTe3Ba2MnCu14O28+ and Sn8SbTe4Ba2MnCu14O28+ are the 23rd and 24th compounds found to superconduct above room temperature, with the latter being the first to go above 400 Kelvin.