Critical Temperature for Superconductors

The critical temperature for superconductors is the temperature at which the electrical resistivity of a metal drops to zero. The transition is so sudden and complete that it appears to be a transition to a different phase of matter; this superconducting phase is described by the BCS theory. Several materials exhibit superconducting phase transitions at low temperatures. The highest critical temperature was about 23 K until the discovery in 1986 of some high temperature superconductors. Materials with critical temperatures in the range 120 K have received a great deal of attention because they can be maintained in the superconducting state with liquid nitrogen (77 K).

Material Tc Gallium 1.1K Aluminum 1.2 K Indium 3.4 K Tin 3.7 K Mercury 4.2 Lead 7.2 K Niobium 9.3 K La-Ba-Cu-oxide 17.9 K Y-Ba-Cu-oxide 92 K Tl-Ba-Cu-oxide 125 K