Crystal Growth & Design最新文献

Commercial α-lactose monohydrate powders contain trace amounts of lactose phosphate impurities. In this work, the influence of lactose phosphate on the crystallization of α-lactose monohydrate from aqueous solutions is experimentally investigated by varying both the seed mass and the initial supersaturation. A novel approach based on pH measurements is proposed to quantify the concentration of lactose phosphate in solution and its incorporation into lactose crystals during the crystallization process. Deionization of lactose solution prior to crystallization using ion-exchange beads effectively removes the lactose phosphate and enables a clear assessment of the impact of these ionic impurities on the crystallization kinetics and the aspect ratio of the resulting lactose crystals.

Lithium-ion batteries are critical for modern energy storage due to their high energy density and long cycle life. However, anode material degradation during cycling significantly impacts capacity retention and battery lifespan. In this study, graphene oxide (GO)-coated BiFeO₃ composites were synthesized using a simple hydrothermal method to enhance the lithium-ion conductivity and overall stability of the anode. The composite materials were characterized through first-principles calculations, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Results show that graphene effectively suppresses the loss of active materials during cycling, improving long-term stability. The graphene coating also enhances ion diffusion, reducing internal resistance. Electrochemical tests revealed that the BiFeO₃-GO achieved a capacity of 562.8 mAh g^–1 after 50 charge–discharge cycles at 100 mA g^–1, significantly outperforming the uncoated BiFeO₃ (277.4 mAh g^–1). This composite demonstrates excellent electrochemical performance, positioning BiFeO₃-GO as a top candidate among oxide anode materials. The graphene coating not only improves conductivity but also strengthens the mechanical stability of the anode, making it more durable during cycling. This study provides insights into the design of high-performance oxide-based anode materials for energy storage applications.

The stoichiometric ratio of the components in the crystals based on squaric acid (SQ) and benzimidazole (BIMD) was altered by the solvent used in crystallization. Crystallization of a 1:1 mixture of SQ and BIMD in water, DMF, and an equal volumetric mixture of acetonitrile and water resulted in the formation of salts with 5:6, 1:2, and 1:1 stoichiometries of squarate anion to benzimidazolium cation, respectively. On the other hand, crystallizing 3:1 and 2:1 stoichiometries of the starting materials in water afforded 3:2 and 2:1 salt-cocrystals, respectively. This study reports the highest number of organic salt crystals prepared by using the same chemical components with different stoichiometric ratios. The solubility of the components and the salts in the solvent and the mixture of solvents used for crystallization played an important role in the stoichiometric variation of the components.

Controlling dendritic solidification is crucial for determining mechanical properties in roll casting. This study employs a transparent succinonitrile (SCN)–Fe₃O₄ model alloy for in situ observation of directional solidification under magnetic fields (50–70 mT). Here, it was found that the magnetic field can progressively thin the dendritic layer, enhancing fragmentation, and widening the kiss point to ∼7 mm at 70 mT. Meanwhile, the field can also promote a transition from coarse dendritic to refined equiaxed structures. A force-flow-interface mechanism is proposed, where magnetic forces generate convection that disrupts transport processes and destabilizes the solid–liquid interface according to the Mullins–Sekerka criterion. Verification with 6061 aluminum alloy confirms that magnetic fields reduce defects, refine grains, and improve tensile properties, providing insights for electromagnetic materials processing.

This work presents a novel cooperative supramolecular engineering strategy based on the simultaneous utilization of halogen bonding (I···N) and hydrogen bonding (H···N) interactions for the directed self-assembly of three structurally distinct nitronyl nitroxide radicals: 2-(4-iodophenyl)-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (1), 2-(4-iodoethynylphenyl)-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (2), and 2-(2,3,5,6-tetrafluoro-4-iodophenyl)-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (3) with 1,4-diazabicyclo[2.2.2]octane (DABCO). We synthesized and characterized cocrystals (1–3)·DABCO containing these iodine-substituted nitronyl nitroxide radicals with varied electronic properties. The primary novelty lies in demonstrating that cooperative dual-mode noncovalent assembly significantly outperforms single-interaction approaches, achieving quantitative enhancement of magnetic exchange interactions by nearly two orders of magnitude from approximately 0 K for unassociated radicals to −78 K for supramolecular assemblies. The 3·DABCO system approaches the literature benchmark for purely organic nitronyl nitroxide materials, representing a substantial advancement in metal-free magnetic coupling strength. Comprehensive theoretical analysis using DFT, energy decomposition analysis, natural bond orbital analysis, and quantum theory of atoms in molecules elucidated the mechanistic basis for cooperative enhancement, revealing orthogonal energetic profiles where halogen bonds exhibit predominantly electrostatic character with significant orbital contributions, while hydrogen bonds show dispersive dominance with minimal orbital involvement. This complementary nature enables additive stabilization without competitive interference between interaction modes. The methodology addresses inherent limitations of single-interaction approaches, providing enhanced predictability and tunability compared with serendipitous discoveries.

Mechanically flexible crystals offer unique opportunities for adaptive materials, yet predictive control over their responses remains a major challenge. Here, we present a chemically unified series of 4-nitrophenol-based cocrystals, cocrystallized with bipyridyl linkers of varied geometries, to systematically map structure–property relationships. Subtle variations in interplanar angles and intermolecular interactions, such as π–π stacking and hydrogen bonding, enable tuning of mechanical responses ranging from brittle fracture to different extents of elastic bending and plastic bending or twistability. This design differs from previous strategies that relied primarily on van der Waals interactions or halogen bonding to impart mechanical compliance to organic crystals. Structural analysis, supported by energy framework calculations, explains the divergent mechanical behaviors. Notably, the studied cocrystal series spans all four canonical structure–property quadrants, manifested through mechanical flexibility, photoluminescence activity, or both. This systematic and comparative study highlights the delicate interplay between molecular packing and supramolecular interactions, providing structure–property correlations that inform emerging design principles for multifunctional crystalline materials for targeted applications.

We report the synthesis, structures, and magnetic properties of a new family of thiocyanate-bridged binuclear cobalt(II) complexes, [Co₂(Xphtpy)₂(μ-SCN)₂(SCN)₂] (Xphtpy = 4′-(4Xphenyl)-2,2′:6′,2″-terpyridine, X = Cl, Br, I), with varying terminal halides in the halogen-functionalized terpyridine ligands. Single-crystal X-ray crystallography reveals that these complexes crystallize in the same monoclinic system P1 space group with nearly identical structural features. Additionally, the structural distortion around the Co²⁺ centers is highly similar, making the halogen-substituent effect play a critical role in tuning the magnetic anisotropy and couplings. Interestingly, the two Co(II) centers are bridged by two SCN^– atoms in a reverse parallel mode. Magnetic studies reveal ferromagnetic interaction transferred by thiocyanates between the Co²⁺ ions and the strength of this interaction decreases as the ligand field on the pseudo-octahedral Co(II) center decreases from Cl^– > Br^– > I^–. Both density functional theory and ab initio calculations show that individual Co(II) centers show giant positive D values, and simulation of magnetic susceptibility predicts a dominant ferromagnetic interaction between these Co(II) centers in all complexes. Ab initio calculations predict that both the magnitude of the D value for individual Co(II) centers and the strength of this magnetic exchange interaction between the Co(II) centers increase as we move toward heavier halides.

The crystal structure of Ritonavir Form IV is reported. The structure was determined by electron diffraction, and the molecular conformation and hydrogen bonding show similarities to those of Forms I and III. Form II is shown to be the most thermodynamically stable of the four known polymorphs.

The growing demand for nonreciprocal optical devices has intensified the need for high-performance magneto-optical materials. Yttrium iron garnet (YIG) stands out for its excellent magnetic and magneto-optical characteristics. In this work, centimeter-sized dysprosium-doped YIG single crystals were successfully synthesized via the top-seeded solution growth method. The integration of Dy³⁺ ions significantly reduces both coercivity and saturation magnetization compared with pure YIG, enabling magnetic saturation under lower external fields. The as-grown crystal exhibits ferrimagnetic behavior with a saturation magnetization of 9.96 emu/g and a coercivity of 8.40 Oe. Postgrowth oxygen annealing effectively suppresses Fe²⁺ and oxygen vacancy defects, further improving the magneto-optical performance. After annealing at 900 °C, the defect concentration is minimized, leading to a reduced coercivity of 5.09 Oe. Moreover, the treated crystal shows enhanced optical transmittance (71.93% at 1550 nm, 76.05% at 2000 nm), and the Faraday rotation angle increased by more than 12% (184°/cm at 1550 nm, 123°/cm at 2000 nm). These results highlight the essential role of oxygen annealing in optimizing crystal quality and magneto-optical functionality, thus providing critical insights for the property design and postprocessing of magneto-optical materials.

Semi-insulating GaN single crystals were successfully grown on patterned GaN/sapphire substrates using hydride vapor phase epitaxy (HVPE), and the dislocation reduction mechanism was investigated. In the initial stage, selective epitaxy was achieved using photolithographically patterned SiO₂/Ti masks, leading to the formation of truncated GaN micropyramids enclosed by (101̅1) planes. Detailed characterization by cathodoluminescence (CL) and Raman spectroscopy revealed that these structures significantly reduced defect density through a dislocation bending mechanism. Subsequently, lateral overgrowth coalescence produced hexagonal pits composed of (112̅2) planes, which further concentrated dislocations toward the center and reduced their density. An in-source codoping strategy with Ga and Fe/Mn metals enabled the successful fabrication of semi-insulating GaN single crystals. X-ray diffraction and optical spectroscopy demonstrated that the obtained crystals exhibited low dislocation density and minimal residual stress, while resistivity measurements confirmed their excellent semi-insulating properties. This approach provides a new pathway for preparing high-quality free-standing semi-insulating GaN substrates and holds significant potential for the development of high-power radio frequency devices.