The CaTiO₃ type defines the perovskite structure, an arrangement that provides the foundations for amazing properties. Some perovskites can even be used to harvest solar power. The structure is based on that of AuCu₃, with Ca going to the “Au” sites and O being on the “Cu” sites. The new thing here is that there are atoms inside the octahedra made from the “Cu” sites. That’s where the Ti atoms go. In terms of our polyhedra-linkage-net idea, the structure is built from Ti-centered O octahedra that share corners to make a primitive cubic framework. The Ca atoms are in the open spaces created by this arrangement, making up their own primitive cubic network.