Lanthanum Aluminate Twinning
Lanthanum aluminate is a member of the perovskite class of ceramics, many of which are able to superconduct at liquid nitrogen temperatures. Perovskites are often characterized by large covalently bonded, closely packed cubic structures that have an atom with a significantly smaller atomic radius located at the center. When electrical fields are applied to perovskites, the smaller, central atom can shift within the crystal lattice without breaking bonds. Although not a superconductor itself, lanthanum aluminate is well adapted as an epitaxial substrate for growing thin films of related superconducting ceramics.