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

{"title":"Review of honeycomb-based Kitaev materials with zigzag magnetic ordering.","authors":"V Ovidiu Garlea, Colin L Sarkis","doi":"10.1107/S2052520624009831","DOIUrl":"10.1107/S2052520624009831","url":null,"abstract":"<p><p>The search for a Kitaev quantum spin liquid in crystalline magnetic materials has fueled intense interest in the two-dimensional honeycomb systems. Many promising candidate Kitaev systems are characterized by a long-range-ordered magnetic structure with an antiferromagnetic zigzag-type order, where the static moments form alternating ferromagnetic chains. Recent experiments on high-quality single crystals uncovered the existence of intriguing multi-k magnetic structures, which evolved from zigzag structures. Those discoveries have sparked new theoretical developments and amplified interest in these materials. We present an overview of the honeycomb materials known to display this type of magnetic structure and provide detailed crystallographic information for the possible single- and multi-k variants.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"11-27"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142998492","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":"Modulation of the modulated magnetic structure of an Ho i-MAX phase described by a magnetic (3+2)-dimensional superspace group.","authors":"Claire V Colin, Quanzheng Tao, Christine Opagiste, Rafik Balou, Johanna Rosen, Thierry Ouisse, Václav Petříček","doi":"10.1107/S2052520624011053","DOIUrl":"10.1107/S2052520624011053","url":null,"abstract":"<p><p>The magnetic structures of the Ho-based i-MAX phase (Mo_2/3Ho_1/3)₂GaC were studied with neutron powder diffraction at low temperature. (Mo_2/3Ho_1/3)₂GaC crystallizes in the orthorhombic space group Cmcm. The material undergoes two successive antiferromagnetic transitions at T_N1 = 10 K and T_N2 = 7.2 K. The magnetic structure below T_N1 is incommensurate with the propagation vector k₁ = (0, k_y, 0) with k_y = 0.696 (1) at 9 K. For the analysis of the magnetic structure, a group-theoretical approach based on the space group of the nuclear structure and its subgroups was employed. A model in the (3+1)D superspace group Cmcm.1'(0β0)s0ss yielded the most accurate results in neutron powder diffraction refinements. The determined structure was found to be an incommensurate longitudinal amplitude-modulated magnetic structure. Below T_N2, additional magnetic satellites develop. They could be indexed by a propagation vector k₂ = (τ_x, 0, 0) with the τ_x value increasing below T_N2 until it stabilizes at approximately 3 K at 0.075. A magnetic structure determination considering two propagation vectors k₁ and k₂ was carried out using the superspace formalism by building the corresponding (3+2)D model. The determination was based on the observation that the additional magnetic peaks emerge exclusively in the vicinity of the incommensurate magnetic peaks with propagation vector k₁, and not in the vicinity of nuclear peaks. This indicates that only mixed-index reflections were observed, and not reflections purely related to k₂. The magnetic superspace group (MSSG) that was determined is Amma.1' (0,β,0)00s0 (0,0,γ)ss0s. The structure can be described as a longitudinal amplitude-modulated structure, which itself is amplitude-modulated in a perpendicular direction. This represents a very unusual case of a 2-k magnetic structure with no symmetry relation between the propagation vectors.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"37-46"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11801704/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027776","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":"Accurate and efficient representation of intramolecular energy in ab initio generation of crystal structures. Part III: partitioning into torsional groups.","authors":"Isaac J Sugden, David H Bowskill, Benjamin I Tan, Yizu Zhang, Claire S Adjiman, Constantinos C Pantelides","doi":"10.1107/S2052520624010072","DOIUrl":"10.1107/S2052520624010072","url":null,"abstract":"<p><p>We present an approach to reduce this computational cost substantially, based on the partitioning of the molecule into geometrically separated torsional groups, with the dependence of the intramolecular energy and atomic point charges and dependent degrees of freedom on molecular conformation being computed as a linear combination of the contributions of these groups. This can lead to large savings in computational cost without a significant impact on accuracy, as demonstrated in the cases of N-acetyl-para-aminophenol (paracetamol) and methyl 4-hydroxybenzoate (methyl paraben). The approach is also applied successfully to two larger molecules, benzyl [4-(4-methyl-5-[(4-methylphenyl)sulfonyl]-1,3-thiazol-2-yl)phenyl]carbamate (molecule XX from the fifth CSP blind test) and (2S)-2-[4-(3-fluorobenzyloxy)benzylamino]propionamide (safinamide), for which we conduct the first reported CSP study. In both cases, the use of torsional groups results in over 99% reduction in computational cost, which enables the generation of an initial CSP landscape with high-quality structures found within the standard cutoff of 20 kJ mol^-1 for progression to refinement.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"114-127"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11801705/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057721","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 rare case of Na/Zn isomorphism in the crystal structure of non-centrosymmetric zincophosphate Na₅Zn[Zn(PO₄)₃].","authors":"Olga V Yakubovich, Galina V Kiriukhina, Anatoly S Volkov, Olga V Dimitrova","doi":"10.1107/S2052520624011156","DOIUrl":"10.1107/S2052520624011156","url":null,"abstract":"<p><p>A microporous zincophosphate with the idealized formula Na₅Zn[Zn(PO₄)₃] was obtained through high-temperature hydrothermal synthesis and characterized by scanning electron microscopy, microprobe analysis and X-ray diffraction. The orthorhombic compound, which crystallizes in non-centrosymmetric space group Pna2₁ with unit-cell parameters a = 12.9901 (2), b = 16.2647 (3), c = 5.2158 (1) Å and Z = 4, is characterized by a new structure type. Each ZnO₄ tetrahedron shares all O atoms with four phosphate tetrahedra to form groups of five polyhedra, that are further linked via oxygen-bridging contacts of Zn- and P-centered tetrahedra in chains aligned in the c-axis direction. These one-periodic structural fragments [Zn(PO₄)₃]^7- define the prismatic habitus of the crystals. The negatively charged zincophosphate chains are balanced by Na⁺ cations, disposed in an open space between the chains, and somewhat `diluted' with Zn²⁺, Ca²⁺ and Mn²⁺ ions as impurities. A rare case of the Na/Zn occupation of one structural site was found in the structure. Theoretical calculations of possible pathways of alkali metal ion migration through the structure and activation energies revealed that the Li-substituted counterpart Li₅Zn[Zn(PO₄)₃] can be considered as a potential solid electrolyte.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"62-68"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142863125","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":"Structural studies of hydrated rare earth nitrates within the stereoatomic model of crystal structures.","authors":"Anton V Savchenkov, Galina M Kuz'micheva","doi":"10.1107/S2052520624012071","DOIUrl":"10.1107/S2052520624012071","url":null,"abstract":"<p><p>All crystal structures containing nitrate ions, water molecules and one of the rare earth (RE) metal atoms (La-Lu, Y, Sc) were extracted from the Inorganic Crystal Structure Database. The composition of the identified compounds is analyzed in terms of the number of coordinated and uncoordinated water molecules and nitrate ions. Among the resulting compounds, several isotypic and morphotropic series are observed. The structures were analyzed within the stereoatomic model of crystal structures. Coordination numbers of RE metals are calculated using the method of intersecting spheres. The variation of RE-O distances is analyzed over the entire series of metal atoms. Coordination modes of both nitrate ions and water molecules are established. Combinatorial topological types of Voronoi-Dirichlet polyhedra of rare earth metal atoms as coordination centers in the studied compounds are calculated.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"128-134"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027782","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":"High-pressure and low-temperature behaviour of organic ferroelectric (R)-3-quinuclidinol.","authors":"Svetlana S Sharaya, Nikita E Bogdanov, Boris A Zakharov, Elena V Boldyreva","doi":"10.1107/S2052520624012010","DOIUrl":"10.1107/S2052520624012010","url":null,"abstract":"<p><p>High-pressure and low-temperature structural changes in the ferroelectric phase of (R)-3-quinuclidinol are analysed. The changes in unit-cell volume and parameters are continuous both on cooling and under increasing pressure. The anisotropy of the structural strain, however, is found to be different. At high pressures, the shortest possible distances for H...H contacts are achieved. Since the deformation along the polarization axis can be related to spontaneous polarization, different piezoelectric responses may be expected on cooling and under hydrostatic compression.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"104-113"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027773","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":"Structural and magnetic phase transitions in Eu_1-xLa_xFe₃(BO₃)₄ (x = 0, 0.18).","authors":"Ekaterina S Smirnova, Kirill V Frolov, Ekaterina V Sidorova, Timofei A Sorokin, Olga A Alekseeva, Anton V Guskov, Pavel G Gagarin, Irina A Gudim","doi":"10.1107/S2052520624011569","DOIUrl":"10.1107/S2052520624011569","url":null,"abstract":"<p><p>The crystal structures and hyperfine magnetic parameters of EuFe₃(BO₃)₄ and mixed Eu_0.82La_0.18Fe₃(BO₃)₄ were studied over a wide temperature range in order to analyze correlations of the structural and magnetic features and the phase transitions in multiferroic compounds of the rare-earth iron borate family. The chemical compositions of the crystals are reported from X-ray fluorescence analysis. The crystal structures of EuFe₃(BO₃)₄ and Eu_0.82La_0.18Fe₃(BO₃)₄ were determined using single-crystal X-ray diffraction in the temperature range 25-500 K. A structural phase transition is observed in EuFe₃(BO₃)₄ below 89 K which is related to distortions in the interatomic distances and angles. The most significant of which are for R-O, R-B, R-Fe, Fe-O and Fe-Fe distances, and the angles between the BO₃ triangles and the ab plane. There is no structural phase transition in lanthanum-doped EuFe₃(BO₃)₄ based on specific heat measurements (2.2-101.3 K) and structure analysis (25-500 K), and the temperature dependences of the interatomic distances and angles are smooth. The lengths of the superexchange paths needed for the appearance of a structural phase transition in RFe₃(BO₃)₄ have been proposed. Negative thermal expansion is observed for both compounds below 90 K, resulting from a growth of the interatomic Fe-Fe distances in the iron chains during cooling. The largest atomic displacement parameters are observed for O atoms (O2), indicating that they have the highest mobility. The magnetic properties of EuFe₃(BO₃)₄ and Eu_0.82La_0.18Fe₃(BO₃)₄ were analyzed using Mössbauer spectroscopy in the temperature range 4.5-298 K. Néel temperatures (T_N) of 34.57 (1) and 32.22 (1) K are obtained based on Mössbauer spectroscopy for the pure and doped crystals, respectively. The maximum specific heat capacity temperature dependence related to the magnetic phase transition for the doped crystal is observed at 31.2 K. A violation of the strict arrangement of antiferromagnetic ordering in the ab plane in the La-doped crystals at low temperatures is suggested. The magnetic contributions of the two structural positions of the iron ions to the Mössbauer spectra could not be distinguished in either pure and doped compounds, regardless of whether they are in the paramagnetic and antiferromagnetic regions.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"69-83"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142919062","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":"Selective acceleration and inhibition of crystal growth of glass carbamazepine by low-concentration poly(ethylene oxide):effects of drug polymorph.","authors":"Chongchong Tian, Qi Zhang, Jia Xu, Qin Shi","doi":"10.1107/S2052520624010515","DOIUrl":"10.1107/S2052520624010515","url":null,"abstract":"<p><p>Drug polymorphism attracts considerable interest within the pharmaceutical field. Herein, we investigate the impact of low-concentration poly(ethylene oxide) (PEO) on the crystal growth of carbamazepine (CBZ) polymorphs in the glassy state. The addition of 3%(w/w) PEO increases 5.3-fold the bulk crystal growth rates of CBZ form III and 36.7-fold of form IV at 40°C (T_g -11°C). However, the same content of PEO exhibits a negligible effect on the bulk crystal growth of form I. In addition, the effects of PEO on the crystal growth of the CBZ polymorph at the free surface are also explored. In the presence of 3%(w/w) PEO, surface growth rates of forms III and IV of CBZ are accelerated by 4.7-fold and 3.1-fold, respectively. For comparison, the same content of PEO exhibits an unexpected inhibitory effect on the surface growth rates of form I. Molecular-dynamic simulations attribute these polymorph-dependent effects of PEO mainly to the polymer enrichment at the interface and different crystal surface polymer interactions. This study is relevant for understanding the crystallization of amorphous pharmaceutical solids containing polymorphic drugs.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"55-61"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142863127","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":"Crystal structure and doping in synthetic enstatite: an analysis of Li/Fe³⁺-doped single-crystal samples.","authors":"Paolo Ballirano, Beatrice Celata, Alessandro Pacella, Andrea Bloise, Ferdinando Bosi","doi":"10.1107/S2052520624011624","DOIUrl":"10.1107/S2052520624011624","url":null,"abstract":"<p><p>A series of Li⁺/Fe³⁺-doped enstatite crystals of composition Mg_(2-2x)Li_xFe_xSi₂O₆ were synthesized and structurally characterized. Under the selected experimental conditions, we grew three crystals of Pbca orthopyroxene (OPX: x = 0.270-0.313) and two crystals of Pbcn protopyroxene (PPX: x = 0.156-0.164) using the flux-growth technique. The observed variation in the polyhedral volume and distortion of the M2 octahedron as a function of Li/Fe³⁺ doping suggests the presence of an upper limit, at least for the OPX samples. The same linear relation was observed between the polyhedral volume and ⟨M1-O⟩ bond length across all analysed samples, including the endmembers protoenstatite (PEN), orthoenstatite (OEN) and LiFe³⁺Si₂O₆. It seems that the M2 octahedron plays a crucial role in stabilizing the pyroxene topology in either the PEN or the OEN form, because the PPX and OPX samples show two distinct linear relations between the M2O₆ polyhedral volume and ⟨M2-O⟩, with the PPX trend converging toward the parameters of the LiFe³⁺Si₂O₆ endmember, whereas the OPX trend, including OEN, diverges largely from these parameters.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"84-91"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11801706/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057722","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":"Photoelasticity of crystals with the scheelite structure: quantum mechanical calculations.","authors":"Nataliya M Demyanyshyn, Bohdan G Mytsyk, Anatoliy S Andrushchak, Andriy V Kityk","doi":"10.1107/S2052520624011673","DOIUrl":"10.1107/S2052520624011673","url":null,"abstract":"<p><p>We report a complete set of elastic, piezooptic and photoelastic tensor constants of scheelite crystals CaMoO₄, BaMoO₄, BaWO₄ and PbWO₄ determined by density functional theory (DFT) calculations using the quantum chemical software package CRYSTAL17. The modulation parameter, i.e. the change in the crystal optical path normalized by thickness and mechanical stress, was calculated based on piezooptic and elastic compliance tensor constants. For the geometries of the most effective piezo-optic interactions, this parameter reaches rather large values (16-17) × 10^-12 m² N^-1. Anisotropy of the photoelastic and acoustooptic effects is explored by means of indicative surfaces, considering the directions of light propagation and polarization, the direction of uniaxial compression or lattice distortion caused by the propagation of the acoustic wave. DFT calculations indicate BaWO₄ and PbWO₄ crystals as the most effective acousto-optic materials, predicting the figure of merit constant M₂ ∼ 20 × 10^-15 s³ kg^-1. The methodology proposed combines the DFT calculations and photoelasticity caused by uniaxial compression of the crystal lattice, with particular emphasis on its anisotropy. It can be considered as part of optical engineering aimed at preliminary assessment of the photoelastic properties of crystal materials, thus assisting in their selection for synthesis and relevant applications.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":" ","pages":"47-54"},"PeriodicalIF":1.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142998489","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}