Crystal Growth & Design最新文献

The combination of stereochemically active [SeO₃] units with Sb³⁺ cations effectively enhances optical anisotropy and yields sizable birefringence in antimony selenite compounds. However, the stereochemically active lone pairs often induce a red shift in the UV cutoff edge, which may limit the application of these compounds in the short-wave UV region. To overcome this limitation while preserving anisotropic building units, we introduced tetrahedral [TO₄] (T = S, Se) groups into the SeO₃–Sb(III) framework. Two compositionally related crystals, Sb₂(SeO₃)₂SO₄ (ASeS) and Sb₂(SeO₃)₂SeO₄ (ASeSe), were synthesized and characterized. Both maintain short-wave UV cutoffs (≤300 nm), and ASeSe exhibits sizable birefringence of 0.158 at 546 nm. Structure–property analysis attributes the performance to cooperative [SeO₃]/[SbO₅]/[TO₄] (T = S, Se) building units, with the higher polarizability anisotropy of [SeO₄] underpinning the larger birefringence in ASeSe.

The chiral resolution of optically active compounds is essential owing to the different interactions between enantiomers. Although several well-established methods exist for resolving chiral organic compounds, techniques for the chiral resolution of inorganic crystals remain underdeveloped. In this study, we demonstrate the chiral resolution of CsCuCl₃ using organic solvents and an achiral crystalline phase. Whereas crystallization from aqueous solutions typically yields racemic twin crystals, the addition of organic solvents to the crystallization medium led to the formation of enantiopure single crystals of CsCuCl₃. Among the various water-miscible organic solvents, ethylene glycol and 1-pentanol were the most effective, producing enantiomorphic crystals. The crystal morphology was found to depend on the solvent used, indicating its influence on the crystal growth process. Additionally, an achiral crystalline phase, Cs₃Cu₃Cl₈(OH), was obtained during the crystallization. When this achiral phase was used as the seed, homochiral CsCuCl₃ crystals grew on its surface, suggesting that chiral resolution can be induced by crystallization on an achiral template.

The impact of fluid flow on the growth mode of GaN crystals during liquid-phase epitaxial (LPE) growth using the Na-flux method was investigated through a combination of experimental and numerical approaches. MOCVD-GaN patterned substrates were used as seed crystals with two different seed placements: vertical and tilted. A detailed analysis was performed on both the morphological features of the crystal and the characteristics of the fluid flow. Under the vertical placement condition, the fluid flow exhibits a uniform laminar flow state, with the fluid flowing in a direction parallel to the bottom of the seed. This results in a regularly symmetric hexagonal pyramidal morphology of the GaN crystal. In contrast, under the tilted placement condition, the fluid flows in a tilted direction along the [1̅1̅20] crystal orientation of the seed. This promotes coalescence along the [1̅1̅20] direction, resulting in a ridge-like structure aligned along the [1̅1̅20] direction of as-grown GaN crystals. By precisely adjusting and designing the direction and velocity of the fluid flow, the crystal growth mode can be effectively modulated to optimize the morphology of the crystal. These findings not only advance the fundamental understanding of hydrodynamic phenomena in crystal growth but also offer new insights and strategies for process optimization and growth control.

The rational design of high-performance oxide scintillators, such as LYSO:Ce, is hindered by an incomplete understanding of their complex scintillation mechanisms. Here, we introduce a strategy of isovalent (Ge⁴⁺) and heterovalent (Al³⁺, P⁵⁺) codoping to precisely control the defect structure and scintillation properties. This work uncovers how different codoping strategies distinctly modulate performance. Isovalent Ge⁴⁺ codoping synergistically enhances light yield by suppressing deep electron traps and improving thermal stability. In contrast, heterovalent substitutions create a complex interplay to accelerate decay kinetics: while both effectively suppress slow Ce2 emission, they rely on distinct additional pathways─Ce⁴⁺ stabilization for Al³⁺ versus enhanced thermal quenching for P⁵⁺. Critically, this comparative study establishes that the suppression of deep electron traps is the dominant factor driving the light yield increase, an effect potent enough to overcome efficiency losses from thermal quenching (as seen in Al³⁺ codoping). These findings offer novel physical insights and a potent strategy for designing advanced oxide scintillators, paving the way for next-generation ultrafast radiation detection.

In nonphotochemical laser-induced nucleation (NPLIN), an unfocused nanosecond laser pulse with low intensity (≈MW/cm²) triggers nearly instantaneous nucleation in supersaturated solutions, a process that would typically take days or weeks when the solution is left undisturbed. Previous studies have shown that the introduction of nanoparticles into supersaturated solutions enhances the probability of NPLIN measured during a fixed time window, compared to undoped control experiments. However, the precise mechanisms driving this enhancement remain unclear hampering industrial implementation of NPLIN. In this study, we systematically investigate how the properties of doped nanoparticles─specifically their concentration and chemical composition─affect the NPLIN probability in supersaturated urea solutions. We observed that higher laser intensities resulted in elevated NPLIN probabilities at a fixed pegylated gold nanoparticle (AuNP) concentration and supersaturation, while increasing concentrations of AuNPs at a fixed laser intensity and supersaturation interestingly led to higher NPLIN probabilities. Moreover, supersaturated solutions doped with gold nanoparticles exhibited significantly higher NPLIN probabilities compared to silica nanoparticle doped solutions at comparable nanoparticle size and concentration. We interpret these experimental results based on the impurity heating hypothesis as well as recent results highlighting the role of thermocavitation. We furthermore propose a helicopter-view model based on a thermodynamic equilibrium stage sequence. Our findings highlight the significance of nanoparticle properties in the design of heteronucleants optimized for NPLIN applications.

Metal methanesulfonate salts are of current interest, owing to their prevalence in environmental water cycles, strong aqueous electrolytic properties, and wide optical transparency. With the latter, several optical studies have been reported, yet none to date have correlated the degree of hydration to their optical properties, as few metal methanesulfonates crystallize with multiple stable hydrates. We report the selective crystal growth of a new magnesium methanesulfonate hydrate, Mg(SO₃CH₃)₂(H₂O)₄, and the known hydrate, Mg(SO₃CH₃)₂(H₂O)₁₂, by using aqueous [PO₄]^3– or [SO₄]^2– reagents at room temperature. Mg(SO₃CH₃)₂(H₂O)₄ crystallizes in the monoclinic space group P2₁/c (no. 14) with a = 7.9133(2) Å, b = 9.9889(2) Å, c = 7.2123(2) Å, β = 102.626(1)⁰, V = 556.31(2) ų, Z = 2, and D_calcd = 1.711 g cm^–1. The other known salt, Mg(SO₃CH₃)₂(H₂O)₂, is also prepared for a comprehensive comparison of optical properties versus the degree of crystalline hydration. Spectroscopy data and DFT calculations indicate that crystalline hydration has little effect on the optical properties of metal methanesulfonate salts.

As a multifunctional ferroelectric crystal, potassium tantalate niobate (KTa_1–xNb_xO₃, KTN) possesses various significant properties, exhibiting piezoelectric, electro-optic, and pyroelectric effects. Ferroelectric crystals are currently a key research direction for acousto-optic materials, making the acousto-optic effect of KTN crystals highly relevant. This paper modifies the Mach–Zehnder dual-beam interferometer system. By improving its method for applying stress, the photoelastic coefficients of a KTN crystal are accurately measured (p₃₃ = 0.62, p₁₃ = 0.33). Subsequently, the longitudinal acoustic wave velocity under polarized light is measured, and the acousto-optic figure of merit M₂ is calculated to be 33.51 × 10^–15 m³/kg, which is tens of times higher than that of most common acousto-optic materials, such as quartz. The acousto-optic diffraction effect of the KTN crystal is further verified by fabricating a test device, which demonstrates the excellent application potential of KTN in the acousto-optic field.

The behavior of 1,2-diiodotetrafluorobenzene (12tfib) as a halogen bond donor was studied by cocrystallizing it with a series of aromatic nitrogen bases covering a wide range of pK_a values (2.10 ≤ pK_a ≤ 9.60) and comparing the results with those reported for other perfluorinated iodobenzenes. The cocrystal screening was performed by grinding 12tfib and each of the selected bases in a 1:2 donor:acceptor stoichiometric ratio as well as crystallization from solution in a small excess of the acceptor (ratio 1:2.5). Of the 14 bases used in this study, three weakest bases (pK_a below ca. 4) have failed to produce cocrystals, nine intermediate bases (4.85 ≤ pK_a ≤ 6.72) have yielded four new phases, which were only obtainable in grinding experiments and not as pure samples, four 1:1 cocrystals and one 1:2 cocrystal, while the two strongest bases (pK_a above ca. 7.5) have yielded 1:2 cocrystals. A total of eight new solids were studied by single-crystal X-ray diffraction. The three 1:2 cocrystals comprise discrete halogen-bonded trimers with 12tfib acting as a ditopic halogen bond donor to two base molecules. Among the five 1:1 cocrystals, in two, 12tfib was found to act as a monotopic donor; however, in other three, 12tfib was found to be ditopic, with the nitrogen atom of the base being a bifurcated acceptor of a pair of halogen bonds. This highly unusual binding motif has been further investigated by quantum chemical calculations and a detailed CSD survey. The computational study has found that a binding site comprising two converging iodine atoms possesses a wide, single minimum potential, which allows for a more favorable binding of weakly and intermediately basic pyridine (aromatic sp²) nitrogen atoms than a single iodine atom. The CSD survey has shown that the aromatic sp² nitrogen atom acting as a bifurcated halogen acceptor is indeed an extremely rare occurrence (appearing in only ca. 2.2% of the total) but considerably more likely to occur in the presence of ortho-diiodo halogen bond donors.

1,2-Diiodotetrafluorobenzene does not form halogen-bonded cocrystals with weak aromatic nitrogen bases, forms mostly 1:1 cocrystals with intermediates, and 1:2 cocrystals with stronger bases. Three cocrystals display a rare motif with aromatic nitrogen acting as a bifurcated acceptor.

Conventional ZSM-5 zeolites exhibit limited efficiency in converting macromolecular reactants due to diffusion constraints arising from their narrow microporous structure. In this work, a strategy combining precrystallized seeds and diquaternary ammonium templates was developed, which enabled the fast synthesis (3 days) of ZSM-5 nanosheets with a thickness of approximately 2 nm. This method reduced the synthesis time by 57% compared with conventional approaches (7 days). During the catalytic cracking of 1,3,5-triisopropylbenzene (1,3,5-TIPB), the nanosheet zeolites achieved a conversion of 67.2%, representing a 7-fold enhancement over conventional ZSM-5 (9.2%). In situ DRIFTS characterization revealed that this enhanced performance is linked to the hierarchical architecture, which shortens diffusion pathways and facilitates the rapid desorption of olefins from active sites, thereby suppressing coke formation. These findings highlight the potential of this approach for advancing heavy oil catalytic cracking processes.

The photoinduced [2 + 2] photocycloaddition in solid states offers an important pathway for converting light to mechanical energy, and it has potential applications in wireless, remote-controlled actuators and soft robotics. In this work, the topo-[2 + 2] cycloaddition took place when the synthesized halogenindole-containing diarylpropenone derivatives were irradiated with 365 nm light. Notably, the quantitative conversion from 1-(5-fluoro-1H-indol-1-yl)-3-phenylprop-2-en-1-one (5FPEO) to the only single α-type photodimer was achieved, while the cycloaddition of 1-(5-chloro-1H-indol-1-yl)-3-phenylprop-2-en-1-one (5ClPEO), 1-(5-bromo-1H-indol-1-yl)-3-phenylprop-2-en-1-one (5BrPEO), 1-(6-chloro-1H-indol-1-yl)-3-phenylprop-2-en-1-one (6ClPEO), and 1-(5,6-dichloro-1H-indol-1-yl)-3-phenylprop-2-en-1-one (DiClPEO) yielded β-type cyclobutane derivatives due to the different molecular preorganization within the crystals. The photoinduced bending, twisting, and creaking of the molecular crystals were observed, and the cycloaddition was proposed as the driving force for the photomechanical effects. Significantly, when the microcrystals of the photoreactive indole-substituted diarylpropenones were composited in polymer films, we observed more pronounced and robust photomechanically responsive behaviors in air and in the water phase compared with the molecular crystals. It would broaden their application scenarios as adaptive and multifunctional photoactuators.