Acta Crystallographica Section A: Foundations and Advances最新文献

{"title":"Relativistic Dirac-Hartree-Fock X-ray scattering factors. III. Chemically relevant atomic anions for Z = 1-85.","authors":"Hampton Copeland, Yoshihiro Watanabe, Anatoliy Volkov","doi":"10.1107/S2053273326003554","DOIUrl":"https://doi.org/10.1107/S2053273326003554","url":null,"abstract":"<p><p>Relativistic X-ray scattering factors are reported for a broad and systematically defined set of chemically relevant atomic anions, including mono- and multivalent species, for elements with atomic numbers Z = 1-85 [Greenwood & Earnshaw (1997). Chemistry of the Elements]. Dirac-Hartree-Fock wavefunctions were generated using the DFRATOM code [Matsuoka & Watanabe (2001). Comput. Phys. Commun. 139, 218-234], with soft radial confinement applied where necessary to stabilize diffuse anionic states. The influence of this confinement on the resulting X-ray scattering factors is explicitly and systematically analyzed to ensure that the reported data reflect physically meaningful electronic structure trends rather than artifacts of the stabilization procedure. The quality of the resulting wavefunctions was assessed using previously reported high-quality benchmark energies [Visscher & Dyall (1997). At. Data. Nucl. Tables 67, 207-224], radial metrics, and direct comparison of X-ray scattering factors with established reference data for neutral atoms and several monovalent anions [Rez et al. (1994). Acta Cryst. A50, 481-497; Su & Coppens (1997). Acta Cryst. A53, 749-762; Macchi & Coppens (2001). Acta Cryst. A57, 656-662]. To ensure physically meaningful results, an X-ray scattering based perturbation metric was introduced to quantify the impact of confinement on the calculated X-ray scattering factors, together with additional high-sin θ/λ consistency checks. The resulting X-ray scattering factors were computed and tabulated in a format consistent with that used in the International Tables for Crystallography [Maslen et al. (2006). Vol. C, Section 6.1.1, pp. 554-589], facilitating direct crystallographic use. Analysis of representative main-group, transition-metal and heavy p-block elements demonstrates that electron attachment leads to a systematic enhancement of the X-ray scattering factors at small momentum transfer, governed primarily by the expansion of the valence electron density, while the high-sin θ/λ region remains dominated by largely invariant core electron contributions. The data presented here provide the first broad, internally consistent reference set of fully relativistic X-ray scattering factors spanning a wide range of multivalent atomic anions of chemical and crystallographic interest, and represent a natural extension of the studies by Olukayode et al. [Acta Cryst. (2023), A79, 59-79; Acta Cryst. (2023), A79, 229-245].</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"82 Pt 3","pages":"200-217"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147757885","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}

{"title":"On geometric tubular polyhedra of types 2₀₁ and 2₁.","authors":"Daniel Pellicer, Gordon Williams","doi":"10.1107/S2053273326003025","DOIUrl":"https://doi.org/10.1107/S2053273326003025","url":null,"abstract":"<p><p>In this paper we classify the two-orbit polyhedra in classes 2₀₁ and 2₁ that have a line preserved by their symmetry groups. Other classes of two-orbit polyhedra that have been previously classified include the chiral (or type 2) polyhedra, and the polyhedra in classes 2₀ and 2₂. Since all of those polyhedra are affinely irreducible, none of their symmetry groups preserve a line as we see in the examples studied here. The skeleta of the polyhedra described in this paper bear some similarities to carbon nanotubes; however there the vertices of their skeleta all have degree three, whereas the polyhedra studied here all have degree four.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"82 Pt 3","pages":"218-227"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147757880","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}

{"title":"Octagonal tilings with three prototiles.","authors":"April Lynne Say-Awen, Sam Coates","doi":"10.1107/S2053273326002767","DOIUrl":"10.1107/S2053273326002767","url":null,"abstract":"<p><p>Motivated by theoretically and experimentally observed structural phases with octagonal symmetry, we introduce families of octagonal tilings composed of three prototiles. These tilings are defined by substitution rules with inflation factors δ^(m,n) = m + n(1 + √2), where m, n are nonnegative integers. We consider the cases (m, n) = (1, 1), (2, 2), (1, 2), (3, 2) and describe their basic properties. In addition, we discuss variants of the first three cases, and for (1, 1) we derive the relative frequencies of the vertex stars.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"179-190"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147643292","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}

{"title":"Adsorption of C₆₀ on Al₁₃Fe₄(010): a theoretical study.","authors":"Dario Job, Franck Polewczyk, Julian Ledieu, Lucile Dezerald, Emilie Gaudry","doi":"10.1107/S2053273326002962","DOIUrl":"10.1107/S2053273326002962","url":null,"abstract":"<p><p>Despite significant research, the surface properties of quasicrystals and their approximants are not yet fully understood. In this paper, buckminsterfullerene (C₆₀ fullerene) is used as a probe to test the adsorption properties of the (010) surface of the quasicrystalline approximant Al₁₃Fe₄. Using first-principles calculations, we systematically explore 17 distinct adsorption sites and identify several energetically favorable configurations. Our analysis reveals that the symmetry matching between the C₆₀ molecule and the surface is a key parameter governing the interaction strength. Furthermore, surface aluminium atoms are shown to play a crucial role in stabilizing the adsorption. A comparative study with the Al₁₃Co₄(100) surface highlights similarities in the overall interaction trends, yet distinct differences arise due to variations in surface substructure. These findings underline the importance of both atomic composition and local geometric symmetry in molecule-intermetallic surface interactions.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"138-144"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147687092","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}

{"title":"X-ray dynamical diffraction wavefront division interferometer (double-slit diffraction) with an asymmetric monochromator. Corrigendum.","authors":"Vahram Mkrtchyan, Minas Balyan, Sargis Petrosyan, Ashot Aivazyan","doi":"10.1107/S2053273326002287","DOIUrl":"10.1107/S2053273326002287","url":null,"abstract":"<p><p>An error in the article by Mkrtchyan et al. [Acta Cryst. (2025), A81, 438-448] is corrected.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"228"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147507996","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}

{"title":"Glass bead games: enumeration of possible polytypes based on two stacking vectors and applications to the iron-ore sinter phases SFCA and SFCA-I.","authors":"Michael Francesco Salzmann, Volker Kahlenberg, Hannes Krüger, Tim Netzer","doi":"10.1107/S2053273326003505","DOIUrl":"10.1107/S2053273326003505","url":null,"abstract":"<p><p>Polytypes can occur in many inorganic and organic compounds alike. In the most basic scenario, different polytypes of a compound are based on translationally equivalent layers and two equivalent arrangements of adjacent layers. This means there are only two distinct stacking vectors, t₁ and t₂. For this particular situation, we have enumerated the number of principally different polytypes for a given number m of layers in the stacking sequence, under the assumption of the validity of four constraints: (i) periodicity, (ii) exchangeability, (iii) reversibility and (iv) simplicity. Different results are obtained when the reversibility constraint is overturned, a factor that depends on the polar or non-polar character of the underlying layers. The results of this theoretical study have been applied to derive the existing polytypes up to m = 6 for two different polysomes of the family of so-called silico-ferrites of calcium and aluminium (SFCA and SFCA-I, respectively). These phases are of considerable interest to the steel industry, as they represent the primary constituents of the matrix in iron-ore sinters. Finally, the impact of polytypism on the powder diffraction patterns of the SFCAs was investigated and the influence of stacking disorder on the diffractograms was analysed. The resulting collection of simulated powder diffraction patterns may serve as a reference database for the identification of polytype effects in industrial sinters.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":"82 Pt 3","pages":"145-162"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13131315/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147757887","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}

{"title":"The growth and structural characterization of a La_0.67Sr_0.33MnO₃/BaTiO₃ superstructure (superlattice).","authors":"Łukasz Kokosza, Jakub Pawlak, Marianna Marciszko-Wiąckowska, Grzegorz Cios, Piotr Jabłoński, Andrii Naumov, Marek Przybylski, Zbigniew Mitura","doi":"10.1107/S205327332600313X","DOIUrl":"10.1107/S205327332600313X","url":null,"abstract":"<p><p>In this study, we report the structural characterization of a La_0.67Sr_0.33MnO₃/BaTiO₃ superstructure fabricated by pulsed laser deposition. The sample was produced through the successive, alternating deposition of the two materials onto a SrTiO₃ (001) substrate. Structural information was obtained using reflection high-energy electron diffraction, scanning electron microscopy, electron backscatter diffraction and X-ray diffraction. The X-ray experimental data were further analyzed with the aid of a computational statistical model of the superstructure to improve analytical accuracy. The results confirmed that the sample exhibits a high-quality crystallographic structure.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"191-199"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147687039","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}

{"title":"Revisiting Becker-Coppens (1974): updated recipes for estimating extinction factors in spherical crystallites.","authors":"Thomas Kittelmann, Douglas D DiJulio, Shuqi Xu, J I Márquez Damián","doi":"10.1107/S2053273326001245","DOIUrl":"10.1107/S2053273326001245","url":null,"abstract":"<p><p>A technical correction and update of the widely used recipes by Becker & Coppens [Acta Cryst. (1974), A30, 129-147], for the estimation of primary and secondary extinction factors in perfect spherical crystallites or grains, is presented. In the original work, these extinction factors were evaluated numerically from a complicated integral, and simplified analytical approximations to these evaluations constituted the provided recipes. However, these original recipes are plagued by issues of numerical precision in general, and even suffer from complete numerical breakdown in the case of strong extinction effects, especially in backwards scattering. Using modern computing capabilities, the numerical evaluations of the integrals are revisited, and improved recipes are provided with consistent precision guarantees for all Bragg angles and levels of extinction. The new recipes are provided both in a `standard' version, believed to be of suitable precision for any actual analysis of diffraction or transmission data, and a `luxury' reference version with even higher precision. The performance of the new recipes is compared with that of the original work, and in order to facilitate easy adoption by the community, reference implementations are provided for C, C++ and Python languages.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"163-178"},"PeriodicalIF":1.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466223","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}

{"title":"Structural investigation and C₆₀ adsorption on the (100) surface of a 1/1 pseudo-Tsai-type Au-Si-Ho quasicrystalline approximant.","authors":"Wilfried Bajoun Mbajoun, Yu Chin Huang, Girma Hailu Gebresenbut, Cesar Pay Gómez, Vincent Fournée, Julian Ledieu","doi":"10.1107/S2053273325011040","DOIUrl":"10.1107/S2053273325011040","url":null,"abstract":"<p><p>Tsai-type 1/1 quasicrystalline approximants in the Au-Si-RE (RE = Ho, Tb) system are body-centered cubic phases decorated by clusters having their inner part occupied by either a disordered tetrahedron (IT) or a single rare-earth atom (CC). The system investigated in the present study is the Au-Si-Ho(CC) compound having full occupation of the cluster centers by single Ho atoms. We present a detailed study of the structure and reactivity of its (100) surface using scanning tunneling microscopy and X-ray photoelectron spectroscopy. After annealing Au-Si-Ho(CC) between 725 K and 880 K, the surface exhibits a (2 × 2) surface reconstruction. The surface appears to terminate at specific bulk planes intersecting Tsai-type cluster centers. Adsorption of C₆₀ molecules on this surface leads to a film with a hexagonal structure corresponding to a (111) plane of the C₆₀ bulk structure. Compared with a previous report on the (100) surface of the Au-Si-Ho 1/1 approximant having a mixed IT and CC decoration, it appears that cluster center decoration does not affect the surface plane selection rule in Tsai-type approximants. However, the inner decoration affects the atomic structure within the selected surface termination and the structure of C₆₀ thin films formed on these surfaces.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"103-107"},"PeriodicalIF":1.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145931318","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}

{"title":"Exploring oxide quasicrystals in internal space.","authors":"Sebastian Schenk, Martin Haller, Stefan Förster, Wolf Widdra","doi":"10.1107/S2053273325011015","DOIUrl":"10.1107/S2053273325011015","url":null,"abstract":"<p><p>Quantitative assessment of the structural quality of quasicrystals is a challenging task. Whereas diffraction techniques are a powerful tool for the coherently scattering regions, only diffuse scattering addresses structural inhomogeneities. Alternatively, local imaging techniques allow for direct inspection of the structures and for statistical evaluation of tiling elements. In both cases, inspecting the internal space characteristic for quasicrystals offers an additional, more sensitive perspective. Here, we analyze atomically resolved scanning tunneling microscopy images for three dodecagonal oxide quasicrystal (OQC) systems. Upon uplifting the 2D coordinates into a 4D hyperspace, the quasicrystal structure can be discussed in the internal space as well as in the physical space. The quasicrystal acceptance domain in internal space of all three OQCs increases logarithmically with the system size. From the acceptance domain expansion we determine the effective phason elastic constants, which reflect phason disorder within their square-triangle-rhombus tiling.</p>","PeriodicalId":106,"journal":{"name":"Acta Crystallographica Section A: Foundations and Advances","volume":" ","pages":"87-95"},"PeriodicalIF":1.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12954487/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145931296","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}