Superconductors.ORG herein reports the discovery of room temperature superconductors number 25 and 26 – further advancing the world record for high Tc. Sn9SbTe4Ba2MnCu15O30+ displays a critical transition temperature (Tc) near 136C (276F) and Sn10SbTe4Ba2MnCu16O32+ transitions near 141C (285F). Superconductivity at these temperatures was confirmed by averaging numerous resistance and magnetization tests. 141 Celsius is warmer than the melting points of more than 45 different solder alloys. Resistance plot for the progenitor compound Sn9SbTe4Ba2MnCu15O30+ are shown.
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.