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

{"title":"The complex stacking disorder of Fe- and Ru-based 1,1'-(3,6-pyrazabolyl)metallocenes.","authors":"Berthold Stöger, Alexandr Virovets, Mischa Wenisch","doi":"10.1107/S2052520625009758","DOIUrl":"10.1107/S2052520625009758","url":null,"abstract":"<p><p>1,1'-(3,6-Pyrazabolyl)ferrocene [Fc(BHpz)₂] and the corresponding ruthenocene [Rc(BHpz)₂] crystallize as order-disorder (OD) structures with layers of Pma(m) symmetry. Since the m_[100] reflection and the a_[010] glide reflection planes of adjacent layers do not overlap, given one layer, the adjacent layer can be placed in four distinct, but geometrically equivalent, positions. There are accordingly four polytypes of a maximum degree of order (MDO). One analyzed Fc(BHpz)₂ crystal was composed of a mixture of the MDO₁ polytype in four distinct orientations and the MDO₃ polytype. A second crystal was essentially a single crystal of one out of two orientation of MDO₃. In two analyzed crystals of Rc(BHpz)₂, the MDO₁ polytype (P1) was the major polytype and was observed in four or two orientation states, respectively. Pronounced diffuse scattering is attributed to a complex disorder, which cannot be explained by simple growth models. One Rc(BHpz)₂ crystal features additional peaks in the diffraction pattern attributed to fragments of MDO₃.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12869525/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145712885","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":"Floating zone growth of high-purity MgO substrate single crystals.","authors":"Christo Guguschev, Michael Schulze, Andrea Dittmar, Detlef Klimm, Kaspars Dadzis, Thomas Schroeder, Knut Peters, Aakash Pushp","doi":"10.1107/S2052520625010893","DOIUrl":"10.1107/S2052520625010893","url":null,"abstract":"<p><p>MgO single crystals with diameters between 3.5 and 5 mm and lengths up to 40 mm were grown by the optical floating zone technique (OFZ). Despite challenging material properties such as the high melting point of 2825°C, very high evaporation rate and perfect {100} cleaving characteristics, crack-free crystals were grown at high growth rates exceeding 40 mm h^-1 and at high thermal gradients. Chemical investigations revealed that the OFZ technique is suitable for the preparation of substrate crystals with a purity of 5N to facilitate the development of novel demonstrator devices based on epitaxially grown thin films. The achieved purity level is improved by more than one order of magnitude if compared to commercial MgO substrate single crystals graded as high purity.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12869521/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145984322","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":"Disappearance of peculiarly large atomic displacement in the high-temperature phase of magnetite with substitution of Fe²⁺ by Ni²⁺ and Mn².","authors":"Takumi Kitamura, Takahiro Niimi, Hiroki Okudera","doi":"10.1107/S2052520625009928","DOIUrl":"10.1107/S2052520625009928","url":null,"abstract":"<p><p>Single crystal specimens of Fe_2.992O₄ (magnetite), Fe_3-x-yMn_x□_yO₄ (x ≤ 0.980) and Fe_3-x-yNi_x□_yO₄ (x ≤ 0.513, □ denotes point defects) are prepared using a floating-zone technique, and changes in their structural parameter values with x are examined at room temperature. Preferences of Mn, Ni and point defects at A, B and B sites, respectively, are confirmed by single-crystal X-ray diffraction experiments, while preference of Mn at the A site is not perfectly accomplished in Fe_2.010Mn_0.980O₄. Mean-square displacements of atoms along the 3 axis in [111] are peculiarly large at the B site in Fe_2.992O₄ and the displacement decreased smoothly in both series, to nearly half in Fe_2.00Mn_0.980O₄, with increasing amount of heteroatom. On the other hand, displacements normal to the direction show only slight convexity with x due to coexistence of the heteroatom. As a result anisotropy in displacements (dominant in [111] at x = 0) is inverted at x = 0.3 in FeMn series and would expectedly be inverted at x ≃ 0.55 in FeNi series. In spite of different locations of heteroatoms and slightly different inversion points on anisotropy, changes in mean-square displacements at the B site in [111] in these series are found on similar lines with changing amounts of heteroatom. In other words, the amount of this displacement is a function of the amount of Fe²⁺, or remnant electron from the itinerant-electron point-of-view, on the B-site substructure in these compounds. This characteristic lattice mode on the B-site substructure could be interpreted as an average of local distortion of the substructure due to `trimeron' [Senn et al. (2012). Nature, 481, 173-176] and some other modes such as distortion in 〈001〉 [Siratori & Kino (1980). J. Magn. Magn. Mat. 20, 87-90], which moves in the high-temperature structure.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12869524/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146016887","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 structures of mcgovernite and carlfrancisite reconsidered: static disorder or ordered defects and twinning?","authors":"Charles Lake, Robert Von Dreele","doi":"10.1107/S2052520625009175","DOIUrl":"10.1107/S2052520625009175","url":null,"abstract":"<p><p>The minerals mcgovernite and carlfrancisite possess an extraordinary rhombohedral unit cell [mcgovernite: a = b = 8.206 Å and c = 204.118 Å, with the complex formula unit M²⁺₁₉Zn₃(OH)₂₁(AsO₃)(AsO₄)₃(SiO₄)₃ (M = Mn, Mg, Zn); carlfrancisite similar]. Hawthorne [(2018), Mineral. Mag. 82, 1101-1118] reported a single-crystal study using a centrosymmetric model (R3c) containing disorder on three cationic sites and an As^III lone-pair site for both mcgovernite and carlfrancisite. A solution of the structure of mcgovernite from high-resolution synchrotron powder diffraction data suggests a reinterpretation of the crystal structures of mcgovernite and carlfrancisite as noncentrosymmetric R3c with ordered planar defects which allows for merohedral twinning.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"572-581"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145511551","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":"A case for resonant X-ray Bragg diffraction by a collinear antiferromagnet Li₂Ni₃P₄O₁₄.","authors":"Stephen W Lovesey","doi":"10.1107/S2052520625009485","DOIUrl":"10.1107/S2052520625009485","url":null,"abstract":"<p><p>Magnetic axial and polar (Dirac) nickel multipoles contribute to resonant X-ray Bragg amplitudes in a symmetry-informed analysis of monoclinic Li₂Ni₃P₄O₁₄ presented for future diffraction experiments. Magnetic long-range order below a temperature of ≃ 14.5 K can be viewed as a two-dimensional trimerized antiferromagnet with Ni ions in two Wyckoff positions in the centrosymmetric (1) magnetic space group P2₁/c. It permits the coupling to circular polarization in the primary X-ray beam, unlike the corresponding diffraction by an antiferromagnet characterized by anti-inversion (1') and a linear magnetoelectric effect, e.g. historically significant chromium sesquioxide (Cr₂O₃) and Cu₂(MoO₄)(SeO₃) [Lovesey & van der Laan (2024). Phys. Rev. B 110, 174442]. The space group is inferred from neutron Bragg diffraction patterns, without an allowance for permitted Dirac dipoles (anapoles) and quadrupoles [Chikara et al. (2025). Phys. Rev. B 112, 014438].</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"582-586"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12786385/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145511504","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":"Prediction and analysis of symmetry-raising transitions in anilinium tetrafluoroborate.","authors":"Sam Y Thompson, Chloe A Fuller, Samuel J Page, Andrew J Bell, John S O Evans","doi":"10.1107/S2052520625009618","DOIUrl":"10.1107/S2052520625009618","url":null,"abstract":"<p><p>We report the structural and dielectric characterization of anilinium tetrafluoroborate (AnBF₄), a molecular crystal identified as a candidate for symmetry-raising phase transitions using the FERROSCOPE routine. Variable-temperature powder X-ray diffraction and differential scanning calorimetry revealed a sequence of three structural phase transitions between room temperature and 490 K, yielding four polymorphs (A-D), three of which are previously unreported. All structures were solved either by single-crystal X-ray diffraction or ab initio from powder diffraction data. Single crystal experiments indicate diffuse scatter in polymorph C which can be related to the structural changes between the different polymorphs. The structural transitions have been rationalized using group-subgroup relationships. Dielectric measurements show a temperature-dependent response consistent with the structural changes, with the A to B transitions associated with a peak in the dielectric constant.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"587-594"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12786386/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145511486","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 charge density and force-field view of bonding interactions in crystals with photomechanical properties: [Co(NH₃)₅NO₂]ClNO₃ versus [Co(NH₃)₅ONO]ClNO₃.","authors":"Mark Khainovsky, Ekaterina Terekhova, Elena Boldyreva, Vladimir Tsirelson","doi":"10.1107/S2052520625008169","DOIUrl":"10.1107/S2052520625008169","url":null,"abstract":"<p><p>Charge density and local electrostatic and quantum kinetic electron forces acting on the bound atoms in [Co(NH₃)₅NO₂]ClNO₃ (nitro isomer) and [Co(NH₃)₅ONO]ClNO₃ (nitrito isomer) were studied to elucidate to the role of the crystalline environment in the intramolecular nitro-nitrito linkage photoisomerization. Quantum crystallography and orbital-free DFT approaches were applied. In the more stable nitro isomer, the -NO₂^- group forms two hydrogen bonds with the NH₃ ligands, while in the nitrito isomer the -ONO^- group is not involved in any hydrogen bonds, however, it forms van der Waals contacts with surrounding atoms. No bond paths in the electron density were found between the anions NO₃^- and Cl^-, which were previously supposed to play an important role in photoisomerization. Still, these anions do interact with each other in both isomers via an indirect mechanism involving H atoms of -NH₃ ligands. Whereas there is no direct electrostatic interaction between the anions in the nitro isomer, the part of electrons belonging to the Cl^- anion in the nitrito isomer is pulled towards the nucleus of an oxygen atom of the NO₃^- anion, creating a favorable condition for direct interaction between anions through corresponding local electronic forces directed to the nuclei. The link of cation/anion atomic basin volumes relationship and nature of the intermolecular interactions is established.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"506-516"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145342744","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":"Magnetoelastic effect in R₅Pt₂In₄ (R = Tb-Tm) investigated by neutron powder diffraction.","authors":"Aleksandra Deptuch, Stanisław Baran, Lukas Keller, Altifani Rizky Hayyu, Andrzej Szytuła","doi":"10.1107/S205252062500900X","DOIUrl":"10.1107/S205252062500900X","url":null,"abstract":"<p><p>Thermal evolution of the unit-cell parameters a, b and c as well as the unit-cell volume V of R₅Pt₂In₄ (R = Tb-Tm) is derived from the neutron powder diffraction data. For all investigated compounds, the above mentioned parameters show a noticeable change in vicinity of the critical temperature of the magnetic order. At lower temperatures, additional anomalies are found for R = Tb-Er. These anomalies are related to the magnetic phase transitions of the order-order type originating from appearance and/or rapid increase of the magnetic rare earth moment at one of the 4g Wyckoff sites. The above mentioned results indicate presence of the magnetoelastic effect in the investigated intermetallics. Based on the experimental data, the product of compressibility and magnetoelastic coupling in R₅Pt₂In₄ (R = Tb-Tm) is found to be 0.014 (2)%·μ_B^-2.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"528-532"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145470285","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":"The glycolipid flocculosin-A from the fungus Anthracocystis flocculosa, or how to deal with cotton-wool-like crystals.","authors":"Thierry Prangé, Giang Nam Phan, William Shepard, Michel Ponchet, Laurent Lapeyre, Mohamed Mehiri","doi":"10.1107/S2052520625008583","DOIUrl":"10.1107/S2052520625008583","url":null,"abstract":"<p><p>Flocculosin A is a strong antifungal metabolite secreted by the Basidiomycota fungus Anthracocystis flocculosa (formerly Pseudozyma flocculosa). It crystallizes in the form of long, soft cotton-wool-like needles, usually observed together with the mycelium in liquid culture conditions. Many crystallization tests were carried out. Among them, only a very slow cooling technique was able to yield suitable crystals, which were needle-like with a maximum thickness of 5 µm and several millimetres long. These crystals permitted us to record single-crystal X-ray diffraction data and solve the crystal structure as well as to determine the absolute configurations of the three chiral centres present in the two lipid chains.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"502-505"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12786383/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145470332","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":"Unveiling the structure and interactions of silicene grown on MoS₂: insights from hybrid molecular dynamics simulations.","authors":"Alexandre Melhorance Barboza, Luis César Rodríguez Aliaga, Daiara Fernandes de Faria, Ivan Napoleão Bastos","doi":"10.1107/S2052520625009187","DOIUrl":"10.1107/S2052520625009187","url":null,"abstract":"<p><p>The interaction of silicene with MoS₂ surfaces has an important role in determining many properties of these systems. However, the intricate nature of silicene-based systems presents significant challenges for both experimental and computational investigations, often resulting in conflicting reports in the literature. Using molecular dynamics simulations with hybrid potentials, this work investigates the epitaxial growth of silicene on an MoS₂ substrate using a vapor-deposition-like method. The findings reveal that silicene can achieve stability on an MoS₂ substrate in an AB low-buckled configuration when both van der Waals and covalent interactions are considered. In this configuration, the silicene layer exhibits numerous defects, which can be significantly reduced by increasing the substrate temperature. In contrast, when only van der Waals interactions are accounted for, the system becomes unstable, leading to the collapse of the silicene structure into a three-dimensional disordered arrangement of Si atoms. A similar instability is observed in a heterostructure where a silicene sheet is intercalated between two MoS₂ layers. These results, combined with the lattice mismatch observed between silicene and MoS₂, suggest that van der Waals interactions alone are insufficient to ensure the mechanical stability of silicene.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"533-539"},"PeriodicalIF":1.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12786350/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145494476","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}