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Accurate determination of strain tensors from small shifts of reflections measured on a four‐circle diffractometer
Author(s) -
Graafsma H.
Publication year - 1992
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/s0021889891014164
Subject(s) - diffractometer , piezoelectricity , tensor (intrinsic definition) , strain (injury) , infinitesimal strain theory , basis (linear algebra) , least squares function approximation , optics , physics , materials science , mathematical analysis , geometry , mathematics , acoustics , quantum mechanics , statistics , phase (matter) , scanning electron microscope , medicine , estimator
Formulas are given for the derivation of the changes in Bragg angles and the corresponding full asymmetric strain tensor from the shifts of reflections measured on a four‐circle diffractometer. The effects of using either an ω ‐ or a 2 θ ‐scan mode are discussed. A least‐squares program was written on the basis of the derived formulas and applied to data measured on the piezoelectric crystals of AgGaS 2 under the influence of an external electric field. The obtained piezoelectric constants are in good agreement with values determined by conventional methods.