TY  - JOUR
A1  - Gorfman, S. V.
A1  - Tsirelson, Vladimir G.
A1  - Pietsch, Ullrich
T1  - X-ray diffraction by a crystal in a permanent external electric field : general considerations
N2  - The variations of X-ray diffraction intensities from a crystal in the presence of a permanent external electric field is modeled analytically using a first-order stationary perturbation theory. The change in a crystal, induced by an external electric field, is separated into two contributions. The first one is related to a pure polarization of an electron subsystem, while the second contribution can be reduced to the displacements of the rigid pseudoatoms from their equilibrium positions. It is shown that a change of the X-ray diffraction intensities mainly originates from the second contribution, while the influence of the pure polarization of a crystal electron subsystem is negligibly small. The quantities restored from an X-ray diffraction experiment in the presence of an external electric field were analyzed in detail in terms of a rigid pseudoatomic model of electron density and harmonic approximation for the atomic thermal motion. Explicit relationships are derived that link the properties of phonon spectra with E-field-induced variations of a structure factor, pseudoatomic displacements and piezoelectric strains. The displacements can be numerically estimated using a model of independent atomic motion if the Debye - Waller factors and pseudoatomic charges are known either from a previous single-crystal X-ray diffraction study or from density functional theory calculations. The above estimations can be used to develop an optimum strategy for a data collection that avoids the measurements of reflections insensitive to the electric-field-induced variations
Y1  - 2005
SN  - 0108-7673
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Tsirelson, Vladimir G.
A1  - Gorfan, S. V.
T1  - X-ray scattering amplitude of an atom in a permanent external electric field
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Tsirelson, Vladimir G.
A1  - Abramov, Yury Fedorovich
A1  - Zavodnik, Valerie E.
A1  - Stash, Adam I.
A1  - Belokoneva, Elena L.
A1  - Stahn, Jochen
A1  - Pietsch, Ullrich
A1  - Feil, Dirk
T1  - Critical pionts in a crystal an procrystal
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Avilov, Anatoly S.
A1  - Kulygin, Alexander K.
A1  - Pietsch, Ullrich
A1  - Spence, John C. H.
A1  - Tsirelson, Vladimir G.
A1  - Zuo, Ming J.
T1  - Scanning system for high-energy electron diffractometry
Y1  - 1999
UR  - http://www3.interscience.wiley.com/journal/118518709/home?CRETRY=1&SRETRY=0
U6  - https://doi.org/10.1107/S0021889899006755
SN  - 0021-8898
ER  - 
TY  - JOUR
A1  - Avilov, Anatoly S.
A1  - Lepeshov, G. G.
A1  - Pietsch, Ullrich
A1  - Tsirelson, Vladimir G.
T1  - Multipole analysis of the electron density and electrostatic potential in Germanium by high-resolution electron diffraction
Y1  - 2001
SN  - 0022-3697
ER  - 
TY  - JOUR
A1  - Tsirelson, Vladimir G.
A1  - Avilov, Anatoly S.
A1  - Lepeshov, G. G.
A1  - Kuligin, A. K.
A1  - Stahn, Jochen
A1  - Pietsch, Ullrich
A1  - Spence, J. C. H.
T1  - Quantitative Analysis of the Inner-Crystal Electrostatic Potential of several Rock-Salt-Structure Crystals Using Accurate Electron-Diffraction Data
Y1  - 2001
SN  - 1089-5647
ER  - 
TY  - JOUR
A1  - Gorfman, Semen
A1  - Tsirelson, Vladimir
A1  - Pucher, Andreas
A1  - Morgenroth, Wolfgang
A1  - Pietsch, Ullrich
T1  - X-ray diffraction by a crystal in a permanent external electric field : electric-field-induced structural response in alpha-GaPO4
N2  - For the first time, site-selective distortion has been investigated for two different structural units in the ternary compound alpha-GaPO4 under the influence of a permanent external electric field. Based on 54 measured reflection intensities, the electric-field-induced distortion of PO4 and GaO4 tetrahedra in alpha-GaPO4 crystals is evaluated using a model of pseudoatomic displacements introduced recently [Gorfman, Tsirelson & Pietsch (2005). Acta Cryst. A61, 387- 396]. A stronger variation of the P-O bond lengths in the PO4 tetrahedron was found compared to the bonds in the GaO4 tetrahedron. The different distortions of the tetrahedra owing to the electric field were analysed in terms of the valence charge density of alpha-GaPO4 and its topological characteristics. The larger charge of the P pseudoatom compared to the Ga atom was recognized as the main reason for the higher sensitivity of the PO4 tetrahedron to a permanent external electric field
Y1  - 2006
UR  - http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-5724
U6  - https://doi.org/10.1107/S0108767305036111
SN  - 0108-7673
ER  -