Forthcoming article in Acta Crystallographica Section A Foundations and Advances
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Acta Crystallographica Section A: Foundations and Advances covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered.en-gbCopyright (c) 2018 International Union of CrystallographyInternational Union of CrystallographyInternational Union of Crystallographyhttps://journals.iucr.orgurn:issn:0108-7673Acta Crystallographica Section A: Foundations and Advances covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered.text/htmlActa Crystallographica Section A Foundations and Advancestextdaily12002-01-01T00:00+00:00med@iucr.orgActa Crystallographica Section A Foundations and AdvancesCopyright (c) 2018 International Union of Crystallographyurn:issn:0108-7673Forthcoming article in Acta Crystallographica Section A Foundations and Advanceshttp://journals.iucr.org/logos/rss10a.gif
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Still imageBlind lattice parameter determination of cubic and tetragonal phases with high accuracy using a single EBSD pattern
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We propose a reliable method which can accurately derive the Bravais-lattice type and its lattice parameters of unknown phases from a single EBSD pattern without a priori knowledge. By solving the geometric relationships in an EBSD pattern based on a huge overdetermined system of equations, error accumulation can be avoided, with the relative errors confined to ~1% for lattice parameters, <0.4% for axial ratios, and ~0.1° for crystal orientation.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Han et al.doi:10.1107/S2053273318010963International Union of CrystallographyWe propose a reliable method which can accurately derive the Bravais-lattice type and its lattice parameters of unknown phases from a single EBSD pattern without a priori knowledge. By solving the geometric relationships in an EBSD pattern based on a huge overdetermined system of equations, error accumulation can be avoided, with the relative errors confined to ~1% for lattice parameters, <0.4% for axial ratios, and ~0.1° for crystal orientation.enELECTRON BACKSCATTER DIFFRACTION; EBSD; BRAVAIS LATTICE; LATTICE PARAMETER; KIKUCHI PATTERN; ELECTRON BACKSCATTER DIFFRACTION; EBSD; BRAVAIS LATTICE; LATTICE PARAMETER; KIKUCHI PATTERNWe propose a reliable method which can accurately derive the Bravais-lattice type and its lattice parameters of unknown phases from a single EBSD pattern without a priori knowledge. By solving the geometric relationships in an EBSD pattern based on a huge overdetermined system of equations, error accumulation can be avoided, with the relative errors confined to ~1% for lattice parameters, <0.4% for axial ratios, and ~0.1° for crystal orientation.text/htmlBlind lattice parameter determination of cubic and tetragonal phases with high accuracy using a single EBSD pattern textExperimental and theoretical investigations of an X-ray LLL interferometer with a wedge-shaped mirror plate
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An X-ray LLL interferometer with a wedge-shaped mirror plate is experimentally and theoretically investigated.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Tigran H. Eyramjyan et al.doi:10.1107/S2053273318009889International Union of CrystallographyAn X-ray LLL interferometer with a wedge-shaped mirror plate is experimentally and theoretically investigated.enLLL INTERFEROMETERS; WEDGE-SHAPED MIRROR PLATES; PENDELLOSUNG FRINGES; MOIRE FRINGES; SUPERPOSITIONAn X-ray LLL interferometer with a wedge-shaped mirror plate is experimentally and theoretically investigated.text/htmlExperimental and theoretical investigations of an X-ray LLL interferometer with a wedge-shaped mirror platetextIntensive X-ray standing-wave-like fields localized near a surface of a crystalline superlattice
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A resonantly enhanced X-ray standing-wave-like field localized in the vicinity of a surface of a crystalline superlattice is analytically shown to exist.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733I. R. Prudnikovdoi:10.1107/S2053273318009877International Union of CrystallographyA resonantly enhanced X-ray standing-wave-like field localized in the vicinity of a surface of a crystalline superlattice is analytically shown to exist.enX-RAY DIFFRACTION; SUPERLATTICE; LOCALIZED STANDING WAVEA resonantly enhanced X-ray standing-wave-like field localized in the vicinity of a surface of a crystalline superlattice is analytically shown to exist.text/htmlIntensive X-ray standing-wave-like fields localized near a surface of a crystalline superlatticetextAn algebraic approach to cooperative rotations in networks of interconnected rigid units
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This article presents an algebraic approach to the analysis of cooperative rotations in networks of interconnected rigid units wherein the geometric constraints of connectedness reduce, in the small rotation-angle limit, to a homogeneous linear system of equations. The approach is illustrated by application to perovskites, to quartz, and to the hexagonal and tetragonal tungsten bronzes.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Branton Campbell et al.doi:10.1107/S2053273318009713International Union of CrystallographyThis article presents an algebraic approach to the analysis of cooperative rotations in networks of interconnected rigid units wherein the geometric constraints of connectedness reduce, in the small rotation-angle limit, to a homogeneous linear system of equations. The approach is illustrated by application to perovskites, to quartz, and to the hexagonal and tetragonal tungsten bronzes.enRIGID-UNIT MODE; COOPERATIVE ROTATION; GROUP THEORY; SYMMETRY MODE; PEROVSKITE; QUARTZ; TUNGSTEN BRONZEThis article presents an algebraic approach to the analysis of cooperative rotations in networks of interconnected rigid units wherein the geometric constraints of connectedness reduce, in the small rotation-angle limit, to a homogeneous linear system of equations. The approach is illustrated by application to perovskites, to quartz, and to the hexagonal and tetragonal tungsten bronzes.text/htmlAn algebraic approach to cooperative rotations in networks of interconnected rigid unitstextX-ray reflectivity of chemically vapor-deposited diamond single crystals in the Laue geometry
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Absolute X-ray reflectivity of chemically vapor-deposited diamond-single-crystal plates was measured in the Laue geometry. The results are interpreted in terms of solution of the Darwin–Hamilton equations describing radiation transfer in a crystal represented by an ensemble of uncorrelated misoriented blocks.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733S. Stoupin et al.doi:10.1107/S2053273318009439International Union of CrystallographyAbsolute X-ray reflectivity of chemically vapor-deposited diamond-single-crystal plates was measured in the Laue geometry. The results are interpreted in terms of solution of the Darwin–Hamilton equations describing radiation transfer in a crystal represented by an ensemble of uncorrelated misoriented blocks.enCVD DIAMOND; X-RAY REFLECTIVITY; MICROSTRUCTURE; X-RAY TOPOGRAPHY; ROCKING CURVES; LAUE GEOMETRY; DARWIN-HAMILTON EQUATIONSAbsolute X-ray reflectivity of chemically vapor-deposited diamond-single-crystal plates was measured in the Laue geometry. The results are interpreted in terms of solution of the Darwin–Hamilton equations describing radiation transfer in a crystal represented by an ensemble of uncorrelated misoriented blocks.text/htmlX-ray reflectivity of chemically vapor-deposited diamond single crystals in the Laue geometrytextApplication of differential resonant high-energy X-ray diffraction to three-dimensional structure studies of nanosized materials: A case study of Pt–Pd nanoalloy catalysts
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Resonant high-energy X-ray diffraction as a tool to study the structure of materials with limited structural coherence.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Valeri Petkov et al.doi:10.1107/S2053273318009282International Union of CrystallographyResonant high-energy X-ray diffraction as a tool to study the structure of materials with limited structural coherence.enRESONANT HIGH-ENERGY X-RAY DIFFRACTION; ELEMENT-SPECIFIC PAIR DISTRIBUTION FUNCTIONS; NANOSIZED MATERIALS; STRUCTURE-FUNCTION RELATIONSHIPS; STRUCTURAL COHERENCEResonant high-energy X-ray diffraction as a tool to study the structure of materials with limited structural coherence.text/htmlApplication of differential resonant high-energy X-ray diffraction to three-dimensional structure studies of nanosized materials: A case study of Pt–Pd nanoalloy catalyststextIncorporating particle symmetry into orientation determination in single-particle imaging
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In coherent-diffraction-imaging experiments, the symmetry of the particle may complicate and facilitate the solution of the orientation problem and the structure at the same time. For symmetric particles, the correlation-maximization method can find the relative orientations of the diffraction patterns and determine the symmetry of the particle.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Tegze and Borteldoi:10.1107/S2053273318008999International Union of CrystallographyIn coherent-diffraction-imaging experiments, the symmetry of the particle may complicate and facilitate the solution of the orientation problem and the structure at the same time. For symmetric particles, the correlation-maximization method can find the relative orientations of the diffraction patterns and determine the symmetry of the particle.enSINGLE-PARTICLE IMAGING; COHERENT DIFFRACTION IMAGING; X-RAY FREE-ELECTRON LASERS; ORIENTATION; CORRELATION MAXIMIZATION; SYMMETRIC PARTICLES; INTENSITY DISTRIBUTIONIn coherent-diffraction-imaging experiments, the symmetry of the particle may complicate and facilitate the solution of the orientation problem and the structure at the same time. For symmetric particles, the correlation-maximization method can find the relative orientations of the diffraction patterns and determine the symmetry of the particle.text/htmlIncorporating particle symmetry into orientation determination in single-particle imagingtextSpecular reflection intensity modulated by grazing-incidence diffraction in a wide angular range
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A theoretical description is given of the novel X-ray diffraction effect in single-crystal structures with a distorted crystal subsurface based on the dynamical theory of diffraction.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733K. V. Nikolaev et al.doi:10.1107/S2053273318008963International Union of CrystallographyA theoretical description is given of the novel X-ray diffraction effect in single-crystal structures with a distorted crystal subsurface based on the dynamical theory of diffraction.enPLEASE PROVIDE KEYWORDSA theoretical description is given of the novel X-ray diffraction effect in single-crystal structures with a distorted crystal subsurface based on the dynamical theory of diffraction.text/htmlSpecular reflection intensity modulated by grazing-incidence diffraction in a wide angular rangetextMeasuring stress-induced martensite microstructures using far-field high-energy diffraction microscopy
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A forward model algorithm is presented to analyze far-field high-energy diffraction microscopy (ff-HEDM) data sets for materials undergoing martensitic transformation, such as shape memory alloys. This approach is demonstrated on three single- and near-single-crystal NiTi data sets. The results demonstrate a new ability to identify martensite microstructures using ff-HEDM, as well as a need for improvements to the widely accepted maximum work criterion applied to the crystallographic theory of martensite for materials that do not strictly adhere to the fundamental assumptions of that theory.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Ashley Nicole Bucsek et al.doi:10.1107/S205327331800880XInternational Union of CrystallographyA forward model algorithm is presented to analyze far-field high-energy diffraction microscopy (ff-HEDM) data sets for materials undergoing martensitic transformation, such as shape memory alloys. This approach is demonstrated on three single- and near-single-crystal NiTi data sets. The results demonstrate a new ability to identify martensite microstructures using ff-HEDM, as well as a need for improvements to the widely accepted maximum work criterion applied to the crystallographic theory of martensite for materials that do not strictly adhere to the fundamental assumptions of that theory.enHIGH-ENERGY X-RAYS; 3DXRD; SHAPE MEMORY ALLOYS; MARTENSITE; PHASE TRANSITIONSA forward model algorithm is presented to analyze far-field high-energy diffraction microscopy (ff-HEDM) data sets for materials undergoing martensitic transformation, such as shape memory alloys. This approach is demonstrated on three single- and near-single-crystal NiTi data sets. The results demonstrate a new ability to identify martensite microstructures using ff-HEDM, as well as a need for improvements to the widely accepted maximum work criterion applied to the crystallographic theory of martensite for materials that do not strictly adhere to the fundamental assumptions of that theory.text/htmlMeasuring stress-induced martensite microstructures using far-field high-energy diffraction microscopytextFast analytical evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of the electron density
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The exact potential and multipole moment method for evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of electron densities is significantly improved in terms of both speed and accuracy by integrating the exact potential using a fully analytical technique.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Daniel Nguyen et al.doi:10.1107/S2053273318008690International Union of CrystallographyThe exact potential and multipole moment method for evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of electron densities is significantly improved in terms of both speed and accuracy by integrating the exact potential using a fully analytical technique.enELECTROSTATIC INTERACTION ENERGY; CHARGE DENSITY; PSEUDOATOM MODEL.The exact potential and multipole moment method for evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of electron densities is significantly improved in terms of both speed and accuracy by integrating the exact potential using a fully analytical technique.text/htmlFast analytical evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of the electron densitytextVariation of second-order piezoelectric coefficients with respect to a finite strain measure
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Higher-order piezoelectric coefficients are finite strain measure dependent, and therefore consistency between the strain measure used in nonlinear constitutive modelling of piezoelectric materials and higher-order piezoelectric coefficients is required. A general transformation formula for the second-order piezoelectric tensor (elastostriction) is derived, and additionally specific transformation formulae for the piezoelectric coefficients for the crystallographic {\bar4}3m and 6mm classes are presented. As an example, the piezoelectric coefficients are recalculated for GaN and GaAs crystals. The results show that typical variation is about 5%, but for some components it may reach a prominent 20%.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Grzegorz Jurczakdoi:10.1107/S2053273318008628International Union of CrystallographyHigher-order piezoelectric coefficients are finite strain measure dependent, and therefore consistency between the strain measure used in nonlinear constitutive modelling of piezoelectric materials and higher-order piezoelectric coefficients is required. A general transformation formula for the second-order piezoelectric tensor (elastostriction) is derived, and additionally specific transformation formulae for the piezoelectric coefficients for the crystallographic {\bar4}3m and 6mm classes are presented. As an example, the piezoelectric coefficients are recalculated for GaN and GaAs crystals. The results show that typical variation is about 5%, but for some components it may reach a prominent 20%.enPLEASE PROVIDE KEYWORDSHigher-order piezoelectric coefficients are finite strain measure dependent, and therefore consistency between the strain measure used in nonlinear constitutive modelling of piezoelectric materials and higher-order piezoelectric coefficients is required. A general transformation formula for the second-order piezoelectric tensor (elastostriction) is derived, and additionally specific transformation formulae for the piezoelectric coefficients for the crystallographic {\bar4}3m and 6mm classes are presented. As an example, the piezoelectric coefficients are recalculated for GaN and GaAs crystals. The results show that typical variation is about 5%, but for some components it may reach a prominent 20%.text/htmlVariation of second-order piezoelectric coefficients with respect to a finite strain measuretextExplicit construction of the Voronoi and Delaunay cells of W(An) and W(Dn) lattices and their facets
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Voronoi and Delaunay (Delone) cells of the root and weight lattices of the Coxeter–Weyl groups W(An) and W(Dn) are constructed. The face-centred cubic and body-centred cubic lattices are obtained in this context.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Mehmet Koca et al.doi:10.1107/S2053273318007842International Union of CrystallographyVoronoi and Delaunay (Delone) cells of the root and weight lattices of the Coxeter–Weyl groups W(An) and W(Dn) are constructed. The face-centred cubic and body-centred cubic lattices are obtained in this context.enLATTICES; COXETER-WEYL GROUPS; VORONOI AND DELONE CELLS; VOLUMES OF REGULAR POLYTOPESVoronoi and Delaunay (Delone) cells of the root and weight lattices of the Coxeter–Weyl groups W(An) and W(Dn) are constructed. The face-centred cubic and body-centred cubic lattices are obtained in this context.text/htmlExplicit construction of the Voronoi and Delaunay cells of W(An) and W(Dn) lattices and their facetstextEstimating the structure factors in X-ray diffraction
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The meaning of the structure factor and how it impacts on the determination of structures are reassessed. A route to obtaining the structure factors is presented for several data collection methods and crystal qualities.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Paul F. Fewsterdoi:10.1107/S2053273318007593International Union of CrystallographyThe meaning of the structure factor and how it impacts on the determination of structures are reassessed. A route to obtaining the structure factors is presented for several data collection methods and crystal qualities.enSTRUCTURE FACTORS; IMPERFECT CRYSTALS; DIFFRACTION THEORY; SERIAL CRYSTALLOGRAPHY; POWDER DIFFRACTIONThe meaning of the structure factor and how it impacts on the determination of structures are reassessed. A route to obtaining the structure factors is presented for several data collection methods and crystal qualities.text/htmlEstimating the structure factors in X-ray diffractiontextStructure evolution of h.c.p./c.c.p. metal oxide interfaces in solid-state reactions
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The atomic structure of Al2O3/MgAl2O4 interfaces at different growth stages is revealed by scanning transmission electron microscopy. Partial dislocations in the hexagonal close-packed/cubic close-packed oxygen sublattices become increasingly dominant as the growth proceeds, suggesting a dislocation glide mechanism in the late growth stage.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733C. Li et al.doi:10.1107/S205327331800757XInternational Union of CrystallographyThe atomic structure of Al2O3/MgAl2O4 interfaces at different growth stages is revealed by scanning transmission electron microscopy. Partial dislocations in the hexagonal close-packed/cubic close-packed oxygen sublattices become increasingly dominant as the growth proceeds, suggesting a dislocation glide mechanism in the late growth stage.enINTERFACE MIGRATION; PARTIAL DISLOCATIONS; ABERRATION-CORRECTED STEM; H.C.P./C.C.P. (H.C.P./F.C.C.) LATTICES; DISLOCATION GLIDEThe atomic structure of Al2O3/MgAl2O4 interfaces at different growth stages is revealed by scanning transmission electron microscopy. Partial dislocations in the hexagonal close-packed/cubic close-packed oxygen sublattices become increasingly dominant as the growth proceeds, suggesting a dislocation glide mechanism in the late growth stage.text/htmlStructure evolution of h.c.p./c.c.p. metal oxide interfaces in solid-state reactionstextResponse to Fraser & Wark's comments on A new theory for X-ray diffraction
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In response to the comments by Fraser & Wark [(2018), Acta Cryst. A74, https://doi.org/10.1107/S2053273318003959], experimental evidence and an explanation of the new theory in the context of a modified Ewald sphere construction are presented.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Paul F. Fewsterdoi:10.1107/S2053273318007489International Union of CrystallographyIn response to the comments by Fraser & Wark [(2018), Acta Cryst. A74, https://doi.org/10.1107/S2053273318003959], experimental evidence and an explanation of the new theory in the context of a modified Ewald sphere construction are presented.enDIFFRACTION THEORY; POWDER DIFFRACTION; SMALL CRYSTALSIn response to the comments by Fraser & Wark [(2018), Acta Cryst. A74, https://doi.org/10.1107/S2053273318003959], experimental evidence and an explanation of the new theory in the context of a modified Ewald sphere construction are presented.text/htmlResponse to Fraser & Wark's comments on A new theory for X-ray diffractiontextGroups, Graphs and Random Walks. Edited by Tullio Ceccherini-Silberstein, Maura Salvatori and Ecaterina Sava-Huss. Cambridge University Press, 2017. Pp. 536. Price GBP 65.00 (paperback). ISBN 9781316604403.
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Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Jean-Guillaume Eondoi:10.1107/S2053273318006873International Union of CrystallographyenBOOK REVIEW; GROUP THEORY; GRAPH THEORYtext/htmlGroups, Graphs and Random Walks. Edited by Tullio Ceccherini-Silberstein, Maura Salvatori and Ecaterina Sava-Huss. Cambridge University Press, 2017. Pp. 536. Price GBP 65.00 (paperback). ISBN 9781316604403.textComments on A new theory for X-ray diffraction
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Fewster [(2014), Acta Cryst. A70, 257–282] claimed that a new theory of X-ray diffraction is required, and that small crystallites will give rise to scattering at angles of exactly twice the Bragg angle, whatever their orientation. This article demonstrates that this theory is in error.Copyright (c) 2018 International Union of Crystallographyurn:issn:2053-2733Fraser and Warkdoi:10.1107/S2053273318003959International Union of CrystallographyFewster [(2014), Acta Cryst. A70, 257–282] claimed that a new theory of X-ray diffraction is required, and that small crystallites will give rise to scattering at angles of exactly twice the Bragg angle, whatever their orientation. This article demonstrates that this theory is in error.enDIFFRACTION THEORY; POWDER DIFFRACTION; SMALL CRYSTALSFewster [(2014), Acta Cryst. A70, 257–282] claimed that a new theory of X-ray diffraction is required, and that small crystallites will give rise to scattering at angles of exactly twice the Bragg angle, whatever their orientation. This article demonstrates that this theory is in error.text/htmlComments on A new theory for X-ray diffractiontext