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

{"title":"Structural phase transitions, dehydration and decomposition of ammonium hypodiphosphates.","authors":"Katarzyna A Ślepokura, Paulina Kurowska, Daria Budzikur-Maciąg, Vasyl Kinzhybalo","doi":"10.1107/S2052520625004408","DOIUrl":"10.1107/S2052520625004408","url":null,"abstract":"<p><p>The ferroelectric diammonium hypodiphosphate, (NH₄)₂(H₂P₂O₆) (3), is the only known so far ammonium salt of hypodiphosphoric acid, H₄P₂O₆. A series of seven new ammonium salts is reported: triclinic (P1) (1) and monoclinic (C2/c) (2) polymorphs of monoammonium (NH₄)(H₃P₂O₆), isostructural (NH₄)₅(H₂P₂O₆)(HP₂O₆)·H₂O (4) and (NH₄)₃(HP₂O₆) (5), and tetraammonium (NH₄)₄(P₂O₆) (6), (NH₄)₄(P₂O₆)·H₂O (7) and (NH₄)₄(P₂O₆)·2H₂O (8). Monoammonium hypodiphosphates 1 and 2 crystallize in perovskite-type structures. Form 1 undergoes an order-disorder phase transition related to the dynamics of ammonium cations, the unit-cell doubling and no change in space group type. Dehydration-decomposition of 4 leads to the equimolar mixture of 3 and 5, whereas dehydration of dihydrate 8 proceeds in two steps, resulting in the formation of monohydrate 7 and then anhydrate 6. Compound 7 undergoes a reversible phase transition (P2₁/c ↔ C2/c) concerned with the reorganization of the hydrogen-bond network. Thermal analysis (DSC and TG-DTA) and variable-temperature microsample powder X-ray diffraction were used to analyse the phase transitions, dehydration and decomposition processes.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"407-417"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582803","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":"Structures of phosphonitrides in light of the extended Zintl-Klemm concept.","authors":"Angel Vegas, Hussien H Osman, Alfonso Muñoz, Vladislav A Blatov, Francisco Javier Manjón","doi":"10.1107/S2052520625004263","DOIUrl":"10.1107/S2052520625004263","url":null,"abstract":"<p><p>The extended Zintl-Klemm concept (EZKC) is applied to explain the crystalline structures of phosphonitrides (also known as nitridophosphates in the chemical literature). The examples of (AE)₂AlP₈N₁₅(NH) (AE = Ca, Sr, Ba), Ge^IVPN₃ and MP₂N₄ (M = Be, Ca, Sr, Ba, Ge^II) are mainly discussed, although the examples of LiGaGe and LiGaGeO₄ have been also commented on due to their relation with BeP₂N₄. It is shown that the EZKC provides a better understanding of the structures of these compounds than in previous descriptions. In most of these nitrides, P atoms behave as pseudo-Si atoms and N atoms behave as pseudo-O atoms, so providing a good explanation for the four-connectivity of P atoms forming PN₄ units, which behave as pseudo-SiO₄ units like the SiO₄ units in many polymorphs of SiO₂. In addition, the EZKC shows that the notation of these compounds as phosphonitrides is more appropriate than as nitridophosphates because N atoms act as the anions in these compounds.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"378-394"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12322934/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582804","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 linear/quadratic order parameter coupling description of the Verwey transition in magnetite, Fe₃O₄.","authors":"Michael A Carpenter, Richard J Harrison, James Shaw-Stewart, Kanta Adachi, Mark S Senn, Christopher J Howard","doi":"10.1107/S2052520625004779","DOIUrl":"10.1107/S2052520625004779","url":null,"abstract":"<p><p>The change in symmetry Fd3m → Cc at the Verwey transition in magnetite puts it in a class of phase transitions with linear/quadratic coupling between two separate order parameters. Direct coupling between an order parameter Q_e, to represent an electronic instability, and an order parameter Q_co, to represent cation charge ordering, has the form λQ_eQ_co², with T_c(Q_e) < T_c(Q_co), but there must also be indirect coupling through the common strain, e₆, due to strain coupling terms λe₆Q_e and λe₆Q_co². Q_e has the symmetry of irrep Γ₅⁺ while the pattern of cation charge ordering of Fe²⁺ and Fe³⁺ on octahedral sites depends on some combination of irreps Δ₅, X₁, X₃, W₁ and W₂. The software package ISOVIZ has been used to show how reported patterns of order for the simplified structure in space group P2/c can be understood in terms of a linearly dependent mix of patterns with symmetry Δ₅ and X₁, so that Q_co can be treated in the first instance as though it has the symmetry of Δ₅. Spontaneous strains calculated from published lattice parameters and symmetry-adapted atomic displacements from previous structural refinements in space group Cc have been used to confirm that the two order parameters have different temperature dependences, consistent with this phenomenological treatment. The effect of chemical doping can be understood in terms of the development of local strain heterogeneity which acts to suppress the macroscopic strains and which appears to have a greater influence on charge ordering than on the electronic structure.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"427-436"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12322932/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590230","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":"New insights into structural diversity of open-framework silicates inspired by the exploration of the Cs₂O-CaO-SiO₂ system.","authors":"Sergey M Aksenov","doi":"10.1107/S2052520625005189","DOIUrl":"10.1107/S2052520625005189","url":null,"abstract":"<p><p>The structure of unique compound Cs₄Ca[Si₈O₁₉] reported recently by Kahlenberg [(2025), Acta Cryst. B81, 325-336] contributes to the broader understanding of structure-property relationships in open-framework silicates (as well as silicates with mixed octahedral-tetrahedral frameworks), with potential implications for ion-exchange, catalysis, and materials with tailored thermal expansion.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"376-377"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582802","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":"Multidisciplinary study of thorium mobility: formation of turkestanite and steacyite analogues, and structural insights using an XRD-directed microcrystal preparation technique.","authors":"M Stachowicz, B Bagiński, D E Harlov, P Jokubauskas, J Kotowski, W Matyszczak, A Dąbrowska, R Macdonald","doi":"10.1107/S2052520625004822","DOIUrl":"10.1107/S2052520625004822","url":null,"abstract":"<p><p>Minerals of the ekanite group typically contain Th, U or REE (rare earth elements) as primary structural constituents. The ^CNa analogues of turkestanite, ^ATh^B(Ca,Na)^C(K_1-x□_x)^T(Si₈O₂₀) (□ is vacancy), and steacyite, ^ATh^B(Ca,Na)^C(K_1-x□_x)^T(Si₈O₂₀), isostructural minerals of the ekanite group, were experimentally synthesized during hydrothermal alteration of chevkinite-(Ce). The experiment was conducted at 550°C, 200 MPa, at an oxygen fugacity approximately equivalent to the Ni-NiO (NNO) buffer with NaF and Ca(PO₄)₂ added to the hydrous fluid. Both phases formed as a replacement of chevkinite-(Ce) and earlier alteration products. Their identity was confirmed by electron probe microanalysis and electron backscatter diffraction as ^CNa analogues of turkestanite and steacyite. Further SCXRD, and Raman spectroscopy analyses confirmed that it is a new ^CNa analogue with respect to the ekanite mineral group. Raman spectroscopy revealed the presence of H₂O within the crystal structure. A dedicated FIB workflow was designed to extract single crystals ready for SCXRD analysis. Compositionally, the phase is Na rich and depleted in K, REE and Fe. The mean formula based on 20 O atoms can be written as ^A(Th_0.94U_0.03)_0.97^B(Na_0.96Ca_0.90Mn_0.11Ce_0.02Nd_0.01Fe_0.01)_2.0^C(Na_0.83K_0.07)_0.9^TSi_8.05O₂₀·0.1^C(H₂O). It crystallizes in space group P4/mcc with a = 7.4757 (2) Å, c = 14.9658 (7) Å, V = 836.38 (6) ų, and Z = 2. Compositional variation is represented mainly by the relationship Ca²⁺ + □ → 2Na⁺, where □ is a vacancy which can also be filled by H₂O during crystallization. The synthesis from this study represents the first record of ^CNa analogues of turkestanite and steacyite. A dedicated microcrystal selection technique is presented allowing for easy single-crystal X-ray diffraction.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":"81 Pt 4","pages":"418-426"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12322933/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144793242","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":"The role of the solvent molecule in the crystal packing arrangements of hydrated salts formed by ethacridine and fluorobenzoic acids.","authors":"Artur Mirocki, Mattia Lopresti","doi":"10.1107/S2052520625004433","DOIUrl":"10.1107/S2052520625004433","url":null,"abstract":"<p><p>Three novel hydrated salts of ethacridine: 2-fluorobenzoate dihydrate, 3-fluorobenzoate monohydrate and 4-fluorobenzoate monohydrate were synthesized and structurally characterized using single-crystal X-ray diffraction. Analysis of intermolecular interactions in the crystal packing revealed that the number of water molecules in the asymmetric unit determines the formation of distinct centrosymmetric supramolecular synthons: [...water...acid...]₂ and [...water...water...acid...]₂. Hirshfeld surface analysis and lattice energy calculations were exploited to characterize intermolecular interactions and to elucidate the influence of small stereochemical differences among the three fluorobenzoate isomers on the crystal packing of the obtained molecular complexes.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"395-406"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582805","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":"Call for papers for special issue: Crystal Growth and Related Characterization.","authors":"","doi":"10.1107/S2052520625006845","DOIUrl":"https://doi.org/10.1107/S2052520625006845","url":null,"abstract":"<p><p>Acta Crystallographica Section B invites papers on advanced neutron scattering instrumentation to appear in a special issue of the journal that will be published in 2026.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":"81 Pt 4","pages":"437"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144793241","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":"Symmetry Relationships between Crystal Structures. Second edition. By Ulrich Müller and Gemma de la Flor. IUCr/Oxford Science Publications, 2024. Pp. XVIII + 368. Price GBP 55.00. ISBN 978-0-19-285832-0.","authors":"Massimo Nespolo","doi":"10.1107/S2052520625006080","DOIUrl":"https://doi.org/10.1107/S2052520625006080","url":null,"abstract":"","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":"81 Pt 4","pages":"438-439"},"PeriodicalIF":1.3,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144793243","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":"Magnetic structure determination of multiple phases in the multiferroic candidate GdCrO₃.","authors":"Pascal Manuel, Dmitry Khalyavin, Fabio Orlandi, Laurent Chapon, Wang Xueyun, Tae Hwan Jang, Eun Sang Choi, Sang Wook Cheong","doi":"10.1107/S2052520625001921","DOIUrl":"10.1107/S2052520625001921","url":null,"abstract":"<p><p>Due to their potential applications in low-power consumption and/or multistate memory devices, multiferroic materials have attracted a lot of attention in the condensed matter community. As part of the effort to identify new multiferroic compounds, perovskite-based GdCrO₃ was studied in both bulk and thin film samples. A strong enhancement of the capacitance in a field suggested ferroelectric behaviour but significant leakage and no well developed P-E hysteresis loops were observed. Measurements clearly indicate the existence of a polar phase but only below 2 K (likely connected to Gd ordering). Here the determination of the magnetic structure through neutron diffraction collected on an isotopic ¹⁶⁰GdCrO₃ sample at the WISH diffractometer at ISIS is reported. The presence of three successive magnetic phases as a function of temperature (commensurate, spin re-orientation and incommensurate phases once the Gd order), previously only seen by magnetization, is confirmed. Using the most recent guidelines for reporting the determined structures, we highlight the benefits of using such nomenclature for discussing physical properties and consider possible mechanisms and couplings that led this seemingly rather isotropic system to display the complex structures observed.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"293-301"},"PeriodicalIF":1.3,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12147934/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952055","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":"Cs₄Ca[Si₈O₁₉]: a new mixed tetrahedral-octahedral oxosilicate, its topological features and comparison with other interrupted framework silicates.","authors":"Volker Kahlenberg","doi":"10.1107/S2052520625002537","DOIUrl":"10.1107/S2052520625002537","url":null,"abstract":"<p><p>Single crystals of a previously unknown caesium calcium silicate with the composition Ca₄Ca[Si₈O₁₉] have been obtained during a systematic study of the phase relations and compound formation in the system Cs₂O-CaO-SiO₂. Structure determination was based on a single-crystal diffraction data set recorded at 288 (2) K. The compound crystallizes in the monoclinic space group P2₁/n and has the following basic crystallographic parameters: a = 7.1670 (6) Å, b = 12.0884 (10) Å, c = 12.4019 (10) Å, β = 90.044 (8)°, V = 1074.47 (15) ų, Z = 2. The crystal structure was solved by direct methods. The sample showed twinning by pseudo-merohedry, which was accounted for in the subsequent least-squares refinements resulting in a residual of R1 = 0.036 for 1962 independent observed reflections and 149 parameters. The crystal structure of Cs₄Ca[Si₈O₁₉] belongs to the group of interrupted framework silicates, in which the [SiO₄] tetrahedra are linked in a three-dimensional network consisting of Q⁴ and Q³ groups in a 1:3 ratio. The linear backbones of the framework can be described as loop-branched dreier single chains. These ribbons are parallel to [100], and the translation period of about 7.2 Å along this axis reflects the periodicity of the chains. By sharing common corners, the condensation of these chains along the [001] direction leads to the formation of layers that are parallel to (010) and contain three- and nine-membered rings of tetrahedra. Alternatively, the crystal structure can be described as a mixed tetrahedral-octahedral framework between [SiO₄] tetrahedra and [CaO₆] octahedra containing cavities accommodating the caesium ions coordinated by seven and eight oxygen ligands, respectively. A detailed topological analysis of the mixed framework based on natural tiles is presented. Indeed, the net can be constructed from a total of only two different cages (tiles) having the following face symbols: [4³] and [3⁴.4⁶.6².7⁸]. A comparison with related silicates containing [Si₈O₁₉] anions and already classified as well as hitherto unclassified interrupted frameworks is presented. Finally, the thermal expansion tensor has been determined in the temperature interval between 193 K and 288 (2) K.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"325-336"},"PeriodicalIF":1.3,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12147939/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143952142","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}