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Relationship between symmetry and estimates of the volume of the unit cell in a powder diffraction pattern
Author(s) -
Wu E.
Publication year - 1993
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/s0021889893002195
Subject(s) - diffraction , powder diffraction , bar (unit) , unit (ring theory) , reflection (computer programming) , symmetry (geometry) , volume (thermodynamics) , nist , crystallography , x ray crystallography , materials science , completeness (order theory) , physics , mathematics , optics , chemistry , geometry , thermodynamics , mathematical analysis , computer science , programming language , mathematics education , natural language processing , meteorology
The relationship between the average of the arbitrary discrepancy n . and the volume V of the unit cell for an n ‐line powder diffraction pattern is studied. A value S n is defined by the relation S n = n V 2/3 . It is a symmetry factor mainly dependent on the reflection conditions of a unit cell. With consideration of the impact of the completeness of the reflections on a real powder diffraction pattern, which is also related to the symmetry factor, a general relation between the real powder diffraction pattern and the volume of the unit cell is established and tested with a number of high quality powder patterns selected from NIST (National Institute of Science and Technology).