Open AccessLayered Atom Arrangements in Complex Materials
Author(s) -
K.E. Sikafus,
Robin W. Grimes,
S.M.Corish,
A.R. Cleave,
Ming Tang,
Christopher R. Stanek,
Blas P. Uberuaga,
James A. Valdez
Publication year - 2005
Language(s) - English
Resource type - Reports
DOI - 10.2172/883642
Subject(s) - stacking , atom (system on chip) , crystallography , crystal structure , oxidation state , sequence (biology) , space group , oxide , metal , materials science , chemistry , physics , x ray crystallography , diffraction , computer science , quantum mechanics , biochemistry , organic chemistry , embedded system , metallurgy
In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}