Acta crystallographica Section B, Structural science, crystal engineering and materials最新文献

{"title":"From mystery to modulation: the structural story of Rb₂[Si₂O₅].","authors":"Clivia Hejny, Volker Kahlenberg, Hannes Krüger","doi":"10.1107/S205252062600819X","DOIUrl":"10.1107/S205252062600819X","url":null,"abstract":"<p><p>The crystal structure of Rb₂[Si₂O₅], a phyllosilicate with previously questionable structural details, has been solved and refined as an incommensurately modulated phase in (3 + 1)-dimensional superspace. This paper describes the monoclinic structure in superspace group C2/c(0β0)s0 with unit-cell parameters a = 9.8662 (6), b = 8.3986 (5), c = 14.7641 (9) Å, β = 90.114 (5)°, V = 1223.4 (1) ų and with modulation wavevector q = 0.377 (1)b*, refined to an R₁ value of 0.0419 for 2603 reflections with intensities greater 3σ. All [SiO₄] tetrahedra within the structure adopt two distinct orientations, and the positions of their constituent silicon and oxygen atoms are modeled using a combination of crenel and positional modulation functions. For the rubidium atoms, harmonic modulation waves were used for the atomic coordinates and the anisotropic displacement parameters. Rubidium cations are predominantly coordinated by six oxygen atoms, forming linkages between adjacent layers built of [SiO₄] tetrahedra. However, the ionic radius of Rb in comparison to the mesh-size of the silicate layer leads to deformation and modulation of the layers. The modulation results in more balanced bond valence sums for rubidium, acceptable Si-O distances and anisotropic displacement parameters, which is not the case for a three-dimensionally periodic structure model with split atom positions. A comparison with related phyllosilicates featuring the same 4.8² net layer topology, but with larger interlayer cations or higher cationic content, reveals that these structures exhibit more relaxed silicate layers. This highlights the role of cation size and content in influencing the structural modulation and strain within the crystal structure of phyllosilicates.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13729040/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148872540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal structure of eveslogite revealed by electron diffraction techniques: a titanosilicate mineral with structurally and compositionally distinct nanoscopic tubular units.","authors":"Emilia Buchsteiner, Mariana Klementová, Wulf Depmeier, Sergey V Krivovichev, Michael Czank, Marco Schowalter, Lukas Palatinus, Ira V Rozhdestvenskaya, Viktor Yakovenchuk, Ute Kolb","doi":"10.1107/S2052520626008620","DOIUrl":"10.1107/S2052520626008620","url":null,"abstract":"<p><p>While silicate nanotubules are unknown in synthetic materials so far, naturally occurring minerals provide several examples of nanoscopic tubular structural building units based upon silicate oxyanions. The crystal structure of eveslogite, a chemically and structurally complex natural silicate mineral from Eveslogchorr mountain, Khibiny massif, Kola Peninsula, Russia, with an idealized sum formula of K_17.5(Ba,Sr)₄(Na,Ca)₄₀[(Ti,Nb,Fe,Mn)₁₁Si₆₂O₁₇₉(OH,F)₁₂(O,OH)₁₃](H₂O) has been solved using modern electron crystallography techniques. This study reveals the first example of a binary structure formed by two different types of transition-metal-modified silicate nanotubular units in a fibrous crystal. One of these is closely related to the nanorod occurring in the unitary nanotubule-based structure of yuksporite, whereas the other is unprecedented and can be considered as an (Nb, Ti)-modified derivative of the [Si₁₂O₃₀]^12- nanotubular units occurring in the binary all-silicate nanotubule-based structures of charoite polytypes. The eveslogite tubular units are packed in a tight arrangement and linked with each other through secondary interactions involving Ca²⁺- and Na⁺-centered polyhedra. The interiors and walls of the tubules are occupied by K⁺ and Ba²⁺ cations as well as H₂O molecules. Topological analysis of the interpolyhedral connectivity shows that the walls of the nanotubules possess topologies related to those of lamprophyllite and delhayelite-group minerals. This topological relationship may indicate possible structural pathways linking these framework types and highlights interesting similarities of exfoliation processes that are well known in modern soft chemistry nanotechnologies. Information-based structural complexity calculations place eveslogite among the most complex minerals known so far. Our study further demonstrates the enormous potential of mineralogy to discover structures unprecedented among the currently known synthetic materials and may serve as an inspiration for the preparation of novel types of artificial nanostructures and their possible technical applications in various fields.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13729042/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149035876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystallography of organic energetic materials: thermoelastic properties and equation of state.","authors":"Mathieu Guerain","doi":"10.1107/S2052520626008322","DOIUrl":"10.1107/S2052520626008322","url":null,"abstract":"<p><p>Energetic molecular crystals exhibit complex behaviour under extreme conditions of temperature and pressure, which critically influences their performance and safety. However, thermoelastic data remain scattered throughout the literature and are rarely analysed within a unified comparative framework, particularly across multiple classes of energetic materials. In this work, crystallographic data for 16 energetic materials were compiled and systematically analysed to investigate their thermal expansion and equation of state parameters. Thermal expansion coefficients and equation of state parameters were extracted or re-evaluated from experimental variable-temperature and high-pressure diffraction-based crystallographic studies. While volumetric thermal expansion is found to be relatively similar across materials, significant differences in anisotropy are observed, strongly governed by molecular packing and polymorphism. High-pressure data show that most materials exhibit bulk moduli in the range 10-20 GPa, while crystal density appears to influence compressibility, although considerable dispersion exists among materials. These results highlight the central role of crystal structure in controlling thermoelastic behaviour and provide a unified framework linking crystal structure, anisotropy and thermoelastic response in energetic molecular crystals for modelling energetic materials under extreme conditions.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13729041/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149011800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A century of structures: historical fidelity and computational fitness in the Inorganic Crystal Structure Database (ICSD).","authors":"Peter Gross, Nik Reeves-McLaren","doi":"10.1107/S2052520626007079","DOIUrl":"10.1107/S2052520626007079","url":null,"abstract":"<p><p>The earliest entries in the Inorganic Crystal Structure Database (ICSD) are both primary historical documents and active computational inputs. They record how the Braggs, Goldschmidt, Vegard, and others established the structural foundations of inorganic chemistry; they are also served, without distinction, to automated pipelines, machine-learning training sets, and high-throughput workflows. We assess 464 ICSD structures from 1913 to 1929 using two independent tools: Eir v1.4.2 (bond valence sums, global instability index) and MaplePy (Madelung part of lattice energy). The pre-1925 median global instability index is 0.077 valence unit (v.u.), below that of modern rock salt reference data (mean 0.192 v.u.); the Braggs' 1913 NaCl gives 0.005 v.u., Bragg's 1922 corundum 0.001 v.u. Early crystallographers were doing simple structures and getting them right. The problem is not quality but metadata. A small number of entries carry genuine topological errors (BeO in NaCl type, SnTe in zinc blende) whose corrective information already exists in database Comments fields but is not machine-readable, not reflected in quality classifications, and relatively invisible to downstream users. We propose six automated fitness-for-purpose flags that surface these cases without removing or modifying any historical record.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13729039/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148705302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seed layer formation by deposition of micro-crystallites on a revolving substrate. Part II: application to some nonlinear effects.","authors":"Arthur Ballato, John Ballato","doi":"10.1107/S205252062600764X","DOIUrl":"10.1107/S205252062600764X","url":null,"abstract":"<p><p>The matrix method of averaging material coefficients of crystallites deposited at an angle to a revolving substrate, disclosed in the prequel [Ballato & Ballato (2024). Acta Cryst. B80, 760-765], is applied to tensors in their indicial form. The results are used to determine averaged nonlinear dielectric, piezoelectric, and elastic constants, as well as linear pyroelectric coefficients, for triclinic crystals; these are further specialized for Laue classes of higher symmetry.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13729043/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148872573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-pressure and high-temperature polymorphism of Na₂CO₃ up to 10 GPa.","authors":"Benedetta Chrappan Soldavini, Marco Merlini, Chiara Mangano, Davide Comboni, Wilson Crichton, Michael Hanfland","doi":"10.1107/S2052520626004956","DOIUrl":"10.1107/S2052520626004956","url":null,"abstract":"<p><p>We report two new high-pressure polymorphs of sodium carbonate, ε and ε-II, stable over ∼2 GPa and 11 GPa, respectively. The ε polymorph exhibits a doubling of the c unit-cell parameter relative to the γ and β phases, crystallizes in space group Cc, and has a bulk modulus of 47.6 (8) GPa, comparable to that of the γ phase. Its stability is confirmed using in situ single-crystal and large-volume press (LVP) experiments. Phase transitions observed over a broad pressure-temperature range allow us to refine the topology of the Na₂CO₃ phase diagram. By integrating precise single-crystal constraints with LVP observations, we propose an updated phase diagram that shows an expanded stability field for the incommensurate γ phase, and reveals a wide stability field for the ε phase at conditions relevant for the Earth's mantle. These results provide improved experimental constraints for the high-pressure behavior of sodium carbonate.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"410-415"},"PeriodicalIF":2.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13470794/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148325061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering unusually large modulations in two related organic hydroxy channel structures.","authors":"Arie van der Lee, Ioan Stroia, Li Bo Huang, Erol Licsandru, Istvan Kocsis, Mihail Deleanu, Christian Hübschle, Mihail Barboiu, Olivier Pérez","doi":"10.1107/S2052520626004932","DOIUrl":"10.1107/S2052520626004932","url":null,"abstract":"<p><p>The incommensurately modulated structures of two related organic hydroxy-channel compounds [(R)-1-(1,3-dihydroxypropan-2-yl)-3-(octan-2-yl)urea, 1; 1-(1,3-dihydroxypropan-2-yl)-3-octylurea, 2] have been determined and compared to the structure of a non-modulated reference compound [(R)-bis-3-(octan-2-yl)urea, 3] lacking hydroxy-channel forming groups. The origin of the modulation is explored through the competition between strong orthogonal urea-urea and hydroxy-hydroxy interactions, though this competition may not be a prerequisite for modulation. Notably, the modulation in these two compounds is unusually pronounced, as shown by the first-order satellite reflections exhibiting intensities comparable to those of the main reflections. This observation is contextualized by comparing the relative intensity differences between main and satellite reflections in a benchmark set of 117 modulated structures. Additionally, an alternative graphical method is introduced to visualize structural modulation within the basic unit cell. This method combines a conventional ball-and-stick representation of the average structure with Lissajous curves that map the spatial modulation onto the unit cell. The curves are color-coded according to the modulation t-parameter, enabling immediate visualization of in-phase and out-of-phase individual modulation displacements.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"375-390"},"PeriodicalIF":2.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13470797/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148215966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping structure-property relationships in a 6-oxo-verdazyl radical by variable pressure crystallography and density functional theory.","authors":"James R Brookes, Varshini J Kumar, Isabelle M Jones, Aston M Summers, Stephanie A Bird, Paul J Low, Stephen A Moggach, Dino Spagnoli","doi":"10.1107/S2052520626006220","DOIUrl":"10.1107/S2052520626006220","url":null,"abstract":"<p><p>The response of the 1,5-tolyl-3-phenyl-6-oxo-verdazyl radical (pTolOV) to pressure in the crystalline state has been investigated using both high-pressure X-ray diffraction techniques and density functional theory (DFT) calculations. Changes in structure, electronic properties such as band gap and density of states, and magnetic exchange interactions have been explored. Structural analysis reveals a phase transition between the P2₁/n and C2/c space groups between 2.30 and 2.73 GPa, and an accompanying increase in molecular point group symmetry in the solid state structure at higher pressures. Modelling using periodic DFT-based methods reveals no significant energy penalty to this phase transition with a small reduction in the band gap upon increasing pressure due to changes in the intermolecular distances, before a sharp increase in band gap with the changes in intermolecular alignment in the C2/c phase. These variations fall in the range 2.02-1.94 eV, and the radical remains a wide-gap semiconductor in the solid state across the pressure range examined. Further DFT calculations with gas-phase models reveal weak antiferromagnetic exchange interactions occurring in antiparallel π-stacked chains in both phases.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"416-432"},"PeriodicalIF":2.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13470795/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148337418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Random in-plane translational stacking faults in the van der Waals superlattice Ba₆Nb₁₁Se₂₈.","authors":"Ke Ma, Yingpeng Yu, Qi Li, Tianping Ying, Qinghua Zhang, Shifeng Jin, Xiaolong Chen","doi":"10.1107/S2052520626004737","DOIUrl":"10.1107/S2052520626004737","url":null,"abstract":"<p><p>The Ba₆M₁₁X₂₈ (M = Nb, Ta; X = S, Se) family of natural van der Waals superlattices hosts highly anisotropic superconductivity and exotic two-dimensional electronic behavior. However, the actual stacking sequences of these superconducting superlattices, crucial for property engineering, remains poorly understood. Here we present a detailed microstructural study of Ba₆Nb₁₁Se₂₈ using aberration-corrected scanning transmission electron microscopy (STEM), powder X-ray diffraction (PXRD) and DIFFaX simulations. We identify intrinsic in-plane translational stacking faults confined to the Ba₃NbSe₅ spacer layers and directly resolve three symmetry-equivalent stacking configurations at the atomic scale. These stacking variants preserve the local coordination environment and occur randomly without correlation between adjacent spacer layers. The stacking disorder leads to characteristic extinction of (10l) reflections in diffraction, which is quantitatively reproduced by simulations based on a random stacking model. Our results establish in-plane translational stacking disorder as an intrinsic structural feature of Ba₆Nb₁₁Se₂₈ and highlight the importance of spacer-layer degrees of freedom in layered van der Waals superlattices.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"369-374"},"PeriodicalIF":2.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148215947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interaction frequencies as a means to design multicomponent forms.","authors":"Paolo P Mazzeo","doi":"10.1107/S205252062600795X","DOIUrl":"https://doi.org/10.1107/S205252062600795X","url":null,"abstract":"<p><p>Computational crystal engineering approaches to design multicomponent solid forms are a popular means to target experiments that are likely to result in successful outcomes. By utilizing statistics of intermolecular interactions across a large database of experimental crystal structures, Stevens et al. [Acta Cryst. (2026), B82, 391-398] provide a rapid means of identifying key synthons for rational cocrystal design.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":"82 Pt 4","pages":"367-368"},"PeriodicalIF":2.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148758100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}