Abstract

Due to their high melting temperatures, it was not until the 1930s that group 4 and 5 refractory metals were synthesized and measured at low temperature. Superconductivity in Nb was first observed in 1930 at the cryogenics laboratory of W. Meissner in Berlin, a few years before his studies on the effect of magnetic flux expulsion from the interior of a superconductor (Meissner and Ochsenfeld, 1933). Among the superconducting metallic elements, niobium exhibits the record critical temperature, 9.25 K; it is also one of the few elemental superconductors exhibiting type II magnetic properties and some non-negligible transport critical current capability. Owing to these remarkable properties, the earliest attempts to make magnets out of superconducting materials, as envisaged by Heike Kamerlingh-Onnes, were made of pure Nb.