A CRYSTAL-CHEMICAL MODEL OF ATOMIC INTERACTIONS .6. INTERMETALLIC PHASE STRUCTURES

Commonly occurring structures are considered from the point of view of a crystal-chemical model of atomic interactions. It is shown that these structures sometimes contain coordination polyhedra distinct from Platonic, Archimedean and Zalgaller's polyhedra. These polyhedra have two or more groups of atoms into which all the vertices of the coordination polyhedron can be divided and which differ in distance from the central atom. The reasons for such polyhedra are considered. The crystal structure of NiTi2 is analyzed and the causes of the quasicrystal state are revealed.