Origin and use of the term metalloid antimony and tellurium, was recorded merely on a 'sometimes' basis. Use of the term metalloid subsequently underwent a period of great flux up to 1940. Consensus as to its application to intermediate or borderline elements did not occur until the ensuing years, between 1940 and 1960. In 1947, Pauling included a reference to metalloids in his classic and influential textbook, "General chemistry: An introduction to descriptive chemistry and modern chemical theory." He described them as 'elements with intermediate properties ... occupy[ing] a diagonal region [on the periodic table], which includes boron, silicon, germanium, arsenic, antimony, tellurium, and polonium.' In 1959
Germanium becomes the allotrope "β-germanium" with the same structure as β-tin. Like silicon, gallium, bismuth, antimony, and water, germanium is one of the few substances that expands as it solidifies (i.e. freezes) from the molten state. Germanium is a semiconductor. Zone refining techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 10, making it one of the purest materials ever obtained. The first metallic material discovered (in 2005) to become a superconductor in the presence of an extremely strong electromagnetic field was an alloy of germanium, uranium, and rhodium. Pure