Discovery of Superconductivity Mercury Superconducting Transition by H. Kamerlingh Onnes (1911) historically the first to show superconduct that its critical nagnetic 019 T. so the amount =42K carry is also limited. I How the Superconductivity Was First Discovered? Superconductive Element m2m画mPHx 图图 atmosphere and the temperature increased. It was ThEN that they activity was first discovered. (Not on cooling article, there is a description that "the tap 出出其 Li: Element With the Highest Tc Materials Transition temp. (K 270°C) superconducting Nb3sn 238(249C the lightest metal of 25(148°C 135~165K ition temperature(Te of 20 K at 48GPa. This elements with low Ra reve a very high ggests that metallie hydrogen mbers will have high transition2 Mercury Superconducting Transition Mercury was historically the first to show superconductivity. Its practical usefulness is limited by the fact that its critical magnetic field is only 0.019 T, so the amount of electric current it can carry is also limited. Discovery of Superconductivity by H. Kamerlingh Onnes (1911) How the Superconductivity Was First Discovered? (This story was told by Prof. P. Kes of Leiden in 1993 at a NATO summer school in Erice, Italy.) There were two assistants working for Onnes, Horst and Dorshman (these names need to be confirmed). The son of Dorshman told Prof. Kes in 1992 the story of the discovery of superconductivity his father used to tell to his son. They were studying the resistance of mercury with a resistance bridge. One day, by pumping on liquid He in the cryostat, they realized that for some reason the resistance bridge did not seem to be working properly because it was not giving any signal. After they stopped the pump, by mistake, they forgot to re-open the valve to release the evaporated He gas from the cryostat. The pressure increased beyond atmosphere and the temperature increased. It was THEN that they noticed that the resistance of mercury recovered! This is how the superconductivity was first discovered. (Not on cooling, but on warming mercury!) In the Leiden Communication article, there is a description that “the tap (valve) Eak2”was used to increase the temperature. Superconductive Elements Table from Burns A15 compounds alloy Materials Transition temp.(K) Al 1.2 (-272°C) Sn 3.4 (-270°C) Pb 7.2 (-266°C) Nb3Sn 23.8 (-249°C) LaSrCuO 40 (-233°C) YBaCuO 90 (-178°C) BiSrCaCuO 107 (-166°C) TlBaCaCuO 125 (-148°C) HgBaCaCuO 135 ~ 165K Li: Element With the Highest TC K. Shimizu et al., Nature 2002, 419, 587. Superconductivity at high temperatures is expected in elements with low atomic numbers. For example, it has been predicted that when hydrogen is compressed to its dense metallic phase (at pressures exceeding 400 GPa), it will become superconducting with a transition temperature above room temperature. Such pressures are difficult to produce in a laboratory setting, so the predictions are not easily confirmed. Under normal conditions lithium is the lightest metal of all the elements, and may become superconducting at lower pressures. In this work, Li shows superconducting at pressures greater than 30 GPa, with a pressure dependent transition temperature (Tc) of 20 K at 48GPa. This is the highest observed Tc of any element; it confirms the expectation that elements with low atomic numbers will have high transition temperatures, and suggests that metallic hydrogen will have a very high Tc