STOICHIOMETRY CATION COORDINATION NUMBER AND A METHOD OF REPRESENTATION OF OXIDE COMPOUNDS AND PHASES RELATED TO FLUORITE STRUCTURE

The oxide structures related to the fluorite structure type are capable of sustaining a high degree of anion sub-stoichiometry. In some binary and ternary mixed oxide systems, ordered intermediate compounds are found which are related to non-stoichiometric oxide phases. The structurally resolved oxide compounds and phases related to fluorite have arrangements which are distorted variants of idealized structures obtained by removing anions from an oxide of the fluorite type. Using this information, a condensed two-dimensional representation is proposed which displays some essential crystal-chemical principles of such oxide compounds and phases. From a consideration of the effect of removing anions from an idealized fluorite structure it was found possible to obtain relationships between overall non-stoichiometry and cation coordination number in mixed oxide systems. © 1969, Walter de Gruyter. All rights reserved.