Acta Crystallographica Section A: Foundations and Advances最新文献

A parsimonious structure model for the icosahedral quasicrystal Cd_5.7Yb. 二十面体准晶体Cd5.7Yb的简约结构模型。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 Epub Date: 2026-07-09 DOI: 10.1107/S2053273326006601

M Feuerbacher

引用次数: 0

Surface-driven size scaling of the lattice parameter, Debye-Waller coefficient and microstrain in nanocrystals. 纳米晶体中晶格参数、德拜-沃勒系数和微应变的表面驱动尺寸缩放。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 Epub Date: 2026-08-03 DOI: 10.1107/S2053273326007345

Sirisha Subbareddy, Erick Agnolin, Marcelo Augusto Malagutti, Narges Ataollahi, Robert Dinnebier, Paolo Scardi

{"title":"Surface-driven size scaling of the lattice parameter, Debye-Waller coefficient and microstrain in nanocrystals.","authors":"Sirisha Subbareddy, Erick Agnolin, Marcelo Augusto Malagutti, Narges Ataollahi, Robert Dinnebier, Paolo Scardi","doi":"10.1107/S2053273326007345","DOIUrl":"10.1107/S2053273326007345","url":null,"abstract":"Nanocrystals exhibit size-dependent structural behaviour because surface and interface effects become increasingly important as the characteristic domain size decreases. In this work, we investigate the size dependence of three diffraction-derived structural parameters - lattice parameter, isotropic Debye-Waller coefficient and microstrain - by combining molecular dynamics simulations of spherical Pd, Fe and Ti nanocrystals with powder diffraction analysis and comparison with representative literature data. The atomistic results show that small nanocrystals are characterized by a mean compressive state together with pronounced surface-stress inhomogeneity, while enhanced atomic displacements are concentrated in the outer coordination shells. On this basis, three simple nanoscale hypotheses are proposed. The lattice parameter is described as an ideal capillarity-driven reference trend with leading 1/D (where D is the particle diameter) behaviour, although comparison with experimental data confirms that this quantity is not universal and may be strongly modified by surface chemistry, defects, non-stoichiometry and morphology. By contrast, the Debye-Waller coefficient follows a more general 1/D decrease, consistent with a surface-shell picture of enhanced vibrational and static disorder. Microstrain arises from surface-stress gradients and, in the small-particle limit, exhibits a natural 1/D2 dependence associated with surface-stress heterogeneity; over broader size ranges, a mixed 1/D + 1/D2 form provides a more effective description. These results support a heuristic surface-driven interpretation of nanoscale structural disorder and clarify the different degrees of generality of the three scaling laws.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"366-376"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13542917/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148663086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Origin and application of the Lorentz factor in X-ray diffraction. x射线衍射中洛伦兹因子的起源和应用。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 Epub Date: 2026-07-07 DOI: 10.1107/S2053273326005917

Fabian Gasser, Josef Simbrunner, Guillaume Freychet, Nicola Demitri, Václav Holý, Roland Resel

{"title":"Origin and application of the Lorentz factor in X-ray diffraction.","authors":"Fabian Gasser, Josef Simbrunner, Guillaume Freychet, Nicola Demitri, Václav Holý, Roland Resel","doi":"10.1107/S2053273326005917","DOIUrl":"10.1107/S2053273326005917","url":null,"abstract":"The Lorentz factor is a fundamental correction factor in quantitative analysis of X-ray diffraction experiments, enabling measured integrated peak intensities to be related to calculated structure factors. In this review, the physical origin of the Lorentz factor, its derivation and practical implementations are presented based on a unified approach, treating the Lorentz factor as the Jacobian relating the experimental measurement coordinates to the reciprocal-space volume element. This approach clarifies the trigonometric and wavelength-dependent contributions to the Lorentz factor and explains the origin of the commonly used `angular-velocity' formulation for rotational measurements. Equations for the Lorentz factor are derived systematically for a broad range of modern X-ray diffraction geometries, including single-crystal and powder diffraction, grazing-incidence diffraction methods, as well as small-angle X-ray scattering. Hereby it is demonstrated that the Lorentz factor sensitively depends not only on the experimental geometry, but also on the type of sample under investigation. In addition, we discuss how the Lorentz correction may be avoided by direct reciprocal-space integration, and the practical limitations of such approaches are pointed out. By providing a unified and comprehensive overview of the Lorentz factor, this review aims to support reliable and consistent intensity evaluation across various modern X-ray diffraction methods.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"350-360"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13542918/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148395482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Tiles from projections of the root and weight lattices of A_n. 从An的根和权格的投影得到的瓦片。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 Epub Date: 2026-07-06 DOI: 10.1107/S2053273326005590

Nazife Ozdes Koca, Mehmet Koca, Rehab Nasser Al Reasi

{"title":"Tiles from projections of the root and weight lattices of An.","authors":"Nazife Ozdes Koca, Mehmet Koca, Rehab Nasser Al Reasi","doi":"10.1107/S2053273326005590","DOIUrl":"10.1107/S2053273326005590","url":null,"abstract":"The root lattice An and its dual weight lattice An* acquire remarkable quasicrystallographic significance through their projections onto the Coxeter plane, where (n + 1)-fold symmetry emerges naturally. The primary objective of this work is to present a general technique for projection of the Voronoi tessellation of the weight lattice An* and apply it for the lattice A4*. The projection of the Voronoi tessellation of the weight lattice A4* produces a totally different tiling scheme than the tiling obtained from the Voronoi cell projection of the lattice A4 which leads to the Penrose tiling with thick and thin rhombuses. The Voronoi cell of the weight lattice A4* is a permutohedron of order 5, comprising 2D faces of regular hexagons and squares in 4D but which project into two types of hexagons and two types of rhombuses with edges of two lengths in proportion to the golden ratio. A detailed structure of the permutohedron with its 3D and 2D facets has been worked out. A centrally symmetric tessellation of the Coxeter plane exhibiting fivefold symmetry has been constructed using four distinct tile types.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"377-382"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148389455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Reducible wavevector star channel groups and symmetry analysis of ordered phases in perovskite crystals. 钙钛矿晶体中可约波向量星形通道群和有序相的对称性分析。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 DOI: 10.1107/S2053273326006297

Il Hwan Kim, Un Ik Kang, Kum Ok Jang, Jong Song Ri, Song Won Kim

{"title":"Reducible wavevector star channel groups and symmetry analysis of ordered phases in perovskite crystals.","authors":"Il Hwan Kim, Un Ik Kang, Kum Ok Jang, Jong Song Ri, Song Won Kim","doi":"10.1107/S2053273326006297","DOIUrl":"10.1107/S2053273326006297","url":null,"abstract":"By generalizing the concepts of the wavevector star channel in the Brillouin zone and its symmetry group [Kim et al. (2017). Acta Cryst. A73, 403-413; Kim et al. (2021). Acta Cryst. A77, 572-592] to a reducible wavevector star containing several Lifshitz stars, new concepts of the reducible wavevector star channel and its symmetry group are defined and methods of finding them are proposed. It is shown that structural distortions, such as octahedral tilting, atomic displacement and Jahn-Teller ordering, characterized by ten reducible stars related to the Lifshitz ones Γ, M, R and X in ferroics and multiferroics belonging to 15 parent space groups of the simple cubic lattice, are described by 105 reducible star channels, allowed by symmetry, and reducible star channel groups are found. The symmetry analysis of ordered phases induced by the reducible representations of the reducible wavevector star channel groups Pm3m[k11(1)k13] and Pm3m[k11(1)k12k13] has been carried out to show that the complex ordered phases observed experimentally in many perovskite crystals, including CaTiO3, SrZrO3, KMnF3, CsPbCl3 and Pb1-xCaxTiO3, can be described by much simpler order parameter models, rather than the ones associated with reducible representations corresponding to the reducible wavevector star of the space group Pm3m.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"392-408"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148862651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Symmetric vertex- and edge-transitive 3-periodic nets. 对称顶点和边传递三周期网。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-09-01 Epub Date: 2026-07-07 DOI: 10.1107/S2053273326005991

Michael O'Keeffe, Michael M J Treacy

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From atoms to a data bank: optimizing transferability of electron-density symmetry. 从原子到数据库：优化电子密度对称的可转移性。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-07-01 Epub Date: 2026-06-12 DOI: 10.1107/S2053273326004651

Paulina Maria Rybicka, Marta Kulik, Vladislav Ignat'ev, Paulina Maria Dominiak

{"title":"From atoms to a data bank: optimizing transferability of electron-density symmetry.","authors":"Paulina Maria Rybicka, Marta Kulik, Vladislav Ignat'ev, Paulina Maria Dominiak","doi":"10.1107/S2053273326004651","DOIUrl":"10.1107/S2053273326004651","url":null,"abstract":"The multipole model provides a significantly improved description of electron density compared with the spherical atom approximation and is widely applied in the crystallographic refinement of X-ray diffraction data. The multipolar atom types from theory and statistical clustering (MATTS) data bank collects multipole model parameters for atom types. These parameters are derived from quantum chemical calculations performed on experimental geometries of model molecules and rely on the concept of transferability between chemically similar atoms. An essential component of each atom type is the definition of the local coordinate system (LCS) and the symmetry of the electron density, which so far have been selected individually using expert judgment during data bank construction. In this work, we focus on the electron densities of atoms from model molecules and atom types from the MATTS data bank. We introduce a systematic procedure in which symmetry constraints are removed during multipole model refinement of model molecules and multiple types of LCS are tested using chemically meaningful directions. We examine how different LCS choices influence the pseudosymmetry, the apparent symmetry of electron density, identified empirically based on the refined multipole model parameters and their statistical significance. Our results show that refinement without symmetry constraints improves the representation of pseudosymmetry and, in some cases, leads to changes in both the values of the multipole model parameters and the assigned symmetry of the electron density. We propose an optimal LCS for each topological kind of atom type and provide clear criteria for symmetry assignment. This work contributes to the future development of the MATTS data bank with improved descriptions of LCSs and transferability of electron-density symmetry.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"256-275"},"PeriodicalIF":2.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13325189/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148222466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Twenty-Sixth General Assembly and International Congress of Crystallography, Melbourne, Australia, 22-29 August 2023. 第二十六届大会暨国际晶体学大会，澳大利亚墨尔本，2023年8月22日至29日。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-07-01 Epub Date: 2026-06-02 DOI: 10.1107/S2053273325001329

引用次数: 0

Symmetries of a dynamical system arising from a biquadratic number field. 由双二次数场产生的动力系统的对称性。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-07-01 Epub Date: 2026-05-19 DOI: 10.1107/S2053273326003967

Kurt Anthony C de Los Santos, Mark L Loyola, Eden Delight P Miro

{"title":"Symmetries of a dynamical system arising from a biquadratic number field.","authors":"Kurt Anthony C de Los Santos, Mark L Loyola, Eden Delight P Miro","doi":"10.1107/S2053273326003967","DOIUrl":"10.1107/S2053273326003967","url":null,"abstract":"We investigate the symmetries of a symbolic dynamical system (Xk, ΓK) of number-theoretic origin. Specifically, we analyze the shift space Xk, defined as the closure of the set Vk of k-free points within the ring of integers {cal O}_{K} of the biquadratic number field K = {bb Q}(sqrt{2},i). The group of shift maps S, which acts on the Minkowski embedding Gamma_{K}cong{bb Z}^{4} by translations, serves as the fundamental action of the system. Our focus is on the homeomorphisms of Xk that interact with the shift action: the automorphism group Aut(Xk, ΓK), consisting of homeomorphisms that commute with every element of S, and the extended symmetry group Sym(Xk, ΓK), which includes homeomorphisms that map the shift action to itself via an automorphism of S. While Aut(Xk, ΓK) is known to be trivial (consisting solely of the shifts themselves), we demonstrate that the extended symmetry group possesses a much richer structure. By leveraging the divisibility and growth properties of {cal O}_{K}, we prove that Sym(Xk, ΓK) is isomorphic to the semi-direct product {bb Z}^{4}times!!hbox{vrule height 4.6pt depth -0.1pt} {rm Stab}(V_{k}), where the stabilizer is explicitly determined by the unit group {cal O}_{K}^{times} and the Galois group {rm Gal}(K/{bb Q}).","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"285-293"},"PeriodicalIF":2.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

MIDAS: a methodological framework for high-speed high-energy diffraction microscopy data reduction. Part I: methodology. MIDAS：高速高能衍射显微镜数据还原的方法学框架。第一部分：方法论。

IF 2.1 4区材料科学

Acta Crystallographica Section A: Foundations and Advances Pub Date : 2026-07-01 Epub Date: 2026-05-28 DOI: 10.1107/S2053273326004006

Hemant Sharma, Jun Sang Park, Peter Kenesei

{"title":"MIDAS: a methodological framework for high-speed high-energy diffraction microscopy data reduction. Part I: methodology.","authors":"Hemant Sharma, Jun Sang Park, Peter Kenesei","doi":"10.1107/S2053273326004006","DOIUrl":"10.1107/S2053273326004006","url":null,"abstract":"The inversion of large-scale diffraction datasets from modern synchrotron sources presents a fundamental challenge in computational crystallography. This paper presents a unified algorithmic framework for the analysis of both near-field (morphological) and far-field (orientational and strain) high-energy diffraction microscopy (HEDM) data. We detail the mathematical formalisms and physical models that form the foundation of this methodology. Key aspects include a generalized model for detector distortion correction, robust algorithms for peak identification in noisy and overlapping patterns, a computationally efficient indexing formalism based on Friedel pair symmetry, and a decoupled iterative refinement scheme that exploits the differing sensitivities of position, orientation and lattice parameters to diffraction observables. We also describe the synergistic integration of near-field and far-field data streams, a critical feature of a truly comprehensive approach. The framework is validated in Part II of this series [Sharma et al. (2026). Acta Cryst. A82, 305-320] using both experimental Ti-7 Al datasets and synthetic reconstructions with known ground truth, achieving orientation accuracy of ∼0.05° and position accuracy of ∼10 µm on experimental data, and a 190× improvement in lattice parameter precision over conventional simultaneous parameter refinement on synthetic data. This integrated framework provides a powerful and extensible solution for turning raw diffraction images into actionable microstructural and micromechanical information.","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"242-255"},"PeriodicalIF":2.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13325191/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148040275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0