The crystal structure of baddeleyite (monoclinic ZrO2)

Abstract

The structure was determined and refined by use of Pa t te rson and Fourier projections on the three faces of the uni t cell. The seven shortest Zr-O separations in the coordination polyhedron around each zirconium range from 2.04 to 2.26 A; since the next nearest Zr-O separat ion is 3.77 ~ , the coordination number of zirconium is clearly seven. The s tructure is an interest ing combinat ion of fluorite-like layers parallel to (100) in which the oxide ions are te t rahedra l ly coordinated, wi th layers in which the oxide ions are in t r iangular coordination. The strong tendency to twin on (100) is explained in terms of this feature of the structure.