The term
high-temperature superconductor was initially employed to designate the new family of cuprate-perovskite
ceramic materials discovered by
J.G. Bednorz[?] and
K.A. Mueller[?] in 1986. These materials are characterized by presenting
superconductivity at a higher temperature than
conventional superconductors (which require temperatures a few degrees above absolute zero), and by other
unconventional features. Recently, other
unconventional superconductors
have been discovered. Some of them also have unusually high values of the critical temperature
Tc, and hence they are sometimes also called high-temperature superconductors, although the record is still held by a cuprate perovskite material (
Tc=133
K, that is -140
°C). Nevertheless it is widely believed that if
room temperature superconductivity[?] is ever achieved it will be in a different family of materials.