A series of intermetallic compounds that have a particular crystal structure and the chemical formula A₃B, where A represents a transition element and B can be either a transition element or a nontransition element. Many A15 compounds exhibit the phenomenon of superconductivity at relatively high temperatures in the neighborhood of 20 K (−424°F) and in high magnetic fields on the order of several tens of teslas (several hundred kilogauss). High-temperature–high-field superconductivity has a number of important technological applications and is a challenging fundamental research area in condensed-matter physics.