title: Twinning and intergrowth of rare earth boride carbides.
abstract: Twins and intergrown crystals of tetragonal rare earth boride carbides, especially those with the La(5)B(2)C(6) structure type, have been investigated by high-resolution electron microscopy and X-ray diffraction. The structure of the twin interface has been determined. It provides an explanation for coherently intergrown domains of different structure. The Sc(3)C(4) structure type is remarkable because it is frequently intergrown with La(5)B(2)C(6)-type phases. It provides, for instance, a model for the intergrowth of other types, e.g. Gd(4)B(3)C(4) and Gd(5)B(2)C(5). The presence of metal-atom square nets in different orientations in the structures accounts for a number of intergrowth phenomena. The possibilities and limitations of X-ray structure determinations are discussed with respect to actual examples.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany. oliver.oeckler@gmx.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Oeckler
authors.forename: Josef
authors.initials: J
authors.lastname: Bauer
authors.forename: Viola
authors.initials: V
authors.lastname: Duppel
authors.forename: Hansjürgen
authors.initials: H
authors.lastname: Mattausch
authors.forename: Arndt
authors.initials: A
authors.lastname: Simon