Accession Number : AD0686807

Title :   THE GEOMETRICAL FACTOR IN THE CRYSTAL CHEMISTRY OF METALS: NEAR-NEIGHBOUR DIAGRAMS,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) DIV OF PURE PHYSICS

Personal Author(s) : Pearson,W. B.

Report Date : 09 JAN 1968

Pagination or Media Count : 8

Abstract : In an attempt to gain some quantitative assessment of the influence of the geometrical principles of Laves for the structures of metals on the occurrence of phases, and on their structural dimensions, a model has been adopted that allows the atoms to be compressed until successively A-A, A-B and B-B contacts are formed. The 'near-neighbour diagrams' that are obtained are thus more suitable for metals than the space filling diagrams of Laves, which are based on an incompressible atom model. They permit an assessment of (1) the relative importance of coordination, and geometrical and bond factors with regard to the occurrence of phases as a function of radius ratio of the component atoms and (2) the influence of these factors on the unit-cell dimensions and atomic parameters of phases with a given structure. The quantitative aspect is introduced by comparing the actual structural dimensions of phases having a given structure, with interatomic separations permitted by the structural geometry. (Author)

Descriptors :   (*CRYSTAL STRUCTURE, DIAGRAMS), METALS, GEOMETRY, PHASE STUDIES, CHEMICAL BONDS, MAGNESIUM COMPOUNDS, ZINC COMPOUNDS, TUNGSTEN COMPOUNDS, INTERMETALLIC COMPOUNDS, THALLIUM COMPOUNDS, SULFIDES, ZINC SULFIDES, CADMIUM COMPOUNDS, IODIDES, CANADA

Subject Categories : Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE