Premium
Observation of antiphase domain structure in chlorapatite
Author(s) -
Yang X.M.
Publication year - 1997
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889896012940
Subject(s) - superstructure , crystallography , diffraction , group (periodic table) , transmission electron microscopy , electron diffraction , displacement (psychology) , chemistry , domain (mathematical analysis) , crystal (programming language) , dark field microscopy , space (punctuation) , materials science , physics , optics , microscopy , mathematics , computer science , mathematical analysis , psychology , organic chemistry , psychotherapist , thermodynamics , programming language , operating system
Single‐crystal electron‐diffraction patterns of synthetic chlorapatite [Ca 5 (PO 4 ) 3 Cl] show weak reflections violating the space group P 2 1 / b . Transmission electron microscopy with dark‐field imaging, using hk 0 ( k = even) reflections, which are allowed for P 2 1 / b , reveals no special features, while dark‐field viewing through certain superstructure reflections [ hk 0 ( k = odd), which are forbidden for this space group] reveals antiphase domains. Diffraction‐contrast experiments show that these domains are related by a displacement vector R = ½[010]. This displacement vector explains the origin of the domain in terms of the ordering of the Cl‐ion position in the channels of chlorapatite.