CrystEngComm最新文献

Two new coordination polymers, CPs [Cd₂(FBA)₂(DMA)₂]·THF (1) and [Mg₃(SBA)₂(EtOH)₂(H₂O)₂(μ₃-OH)₂]·DMA (2) {where, FBA = 4,4′ (hexafluoroisopropylidene)bisbenzoate, SBA = 4,4′-sulfonyldibenzoate, THF = tetrahydrofuran and DMA = N,N-dimethylacetamide}, were synthesized from cadmium and magnesium salts, 1,10-phenanthroline and two different V-shaped flexible ligands by solvothermal methods. The structures were determined by using single crystal X-ray diffraction analysis which revealed that solid 1 crystallizes in the monoclinic space group (P2/n) and adopts a 2D square channel structure with a unique dimeric {Cd₂O₁₂}_n secondary building unit (SBU). Solid 2 also showed a 2D square channel structure and crystallizes in the monoclinic space group C2/c with an extended trimeric SBU of {Mg₃(μ₃-OH)O₂₂}_n. The dielectric measurement study showed dielectric constants (κ) of ∼10.5 for 1 and ∼12.6 for 2 at room temperature. The values of the dielectric constants (κ) of solids 1 and 2 decreased significantly to values of ∼4.6 (solid 1′) and ∼5.6 (solid 2′) after removing the polar solvents, indicating that neutral co-ligand molecules present in the framework significantly affect the material dielectric behaviour. Furthermore, the investigation of impedance spectroscopy (Z′ and Z′′) revealed that the low and high dielectric constant values in the reported solids are attributed to the inherent properties of the bulk material. The reported work offers a suitable example for the construction of high and low-κ coordination polymers (CPs) as gate and interlayer dielectrics for electronic devices by altering the polar solvents present in the framework.

Enhancing the conductivity of silver paste is crucial for achieving high photoelectric conversion efficiency of heterojunction solar cells. In this work, 1-tetradecanol-coated Ag₂O was used as a silver precursor, replacing nano-silver powder in the conventional silver paste. Low-temperature sintering (200 °C) was utilized to establish a conductive pathway between flaky and spherical silver powder, resulting in a low-cost, low-temperature cured silver paste. The effect of 1-tetradecanol content on Ag₂O was investigated, focusing on the electrical conductivity, silver paste rheological properties and adhesion properties of low-temperature cured silver paste film layers. The results showed that the volume resistivity of the paste containing 1-tetradecanol (10 wt%)-coated Ag₂O after sintering at 200 °C for 30 min was 7.44 × 10⁻⁵ Ω cm, which was 35% lower than that of pure silver powder paste, indicating a significant enhancement in electrical conductivity. Furthermore, rheological performance tests demonstrated that the incorporation of Ag₂O was an effective route for enhancing the thixotropy, recovery, and stability of the paste. Meanwhile, an adhesion experiment demonstrated that silver pastes with introduced Ag₂O (≥5 wt%) exhibited a robust bonding to the ITO substrate under low-temperature curing, with an ASTM grade of 5B.

(Boc = tert-butoxycarbonyl)-p-nitro-L-phenylalanyl-p-nitro-L-phenylalanine, a dipeptide characterised by acentric symmetry, self-assembles into microtapes. This study explores its thermal, structural, and nonlinear optical properties. Thermogravimetric Analysis reveals an onset degradation temperature of 190 °C, with primary and secondary peaks at 202 °C and 220 °C, respectively. The crystal structure of the dipeptide was determined through single crystal X-ray diffraction at 100 K, confirming its crystallisation in a monoclinic crystal lattice, space group P2 with two molecules per unit cell. Additionally, optical second harmonic generation polarimetry indicates a nonlinear optical response, with an effective coefficient (d_eff) estimated to be at least 0.67 pm V⁻¹. This value is only four times lower than that of a state-of-the-art phase-matched oriented β-barium borate nonlinear crystal. The crystal is unusually robust against optical damage for an organic crystal, underlining the potential of this dipeptide in nonlinear optical applications.

Lithium carbonate (Li₂CO₃) is essential for lithium-ion battery production, which is pivotal for the advancement of new energy technologies. While extensive research has been conducted on Li₂CO₃ crystallization in neutral solutions, there is a notable gap in understanding its behavior in alkaline environments, which could enhance the efficiency of its production. This study addresses this gap by investigating the reactive crystallization of Li₂CO₃ from LiOH/KOH mixed solutions. The solubility, nucleation, and carbonation processes of Li₂CO₃ in KOH solution were determined. Increasing temperature and decreasing KOH concentration would reduce the solubility of Li₂CO₃. Furthermore, higher temperatures were found to accelerate Li₂CO₃ precipitation and improve lithium recovery rates, achieving an 85.68% recovery with high crystallinity and purity of 98.4% at 363.15 K. The optimized temperature and KOH concentration can significantly enhance Li₂CO₃ crystallization in alkaline solutions. This advancement addresses a critical knowledge gap and provides a valuable reference for the recycling of lithium resources as well as the development of novel preparation processes.

VO₄ units are highly susceptible to distortion induced by crystal fields, and thus, they are favorable for generating second-order nonlinear optical properties in the visible-light frequency range. Among the quaternary compounds containing VO₄ units, vanadates with cations of alkali metals and/or alkaline earth metals exhibit a higher proportion of non-centrosymmetric structures, making them promising candidates for exploring nonlinear optical materials. However, to date, the optical properties of compounds within this category have rarely been characterized. In this work, we successfully synthesized two non-centrosymmetric compounds, NaMg₄(VO₄)₃ and LiMg₄(VO₄)₃. Experimental results showed that NaMg₄(VO₄)₃, which has a bandgap of 3.14 eV, showed a second-harmonic generation response of 1.1 × KDP and 0.4 × AGS at its maximum particle size. LiMg₄(VO₄)₃, with a bandgap of 3.10 eV, showed a second-harmonic generation response of 0.7 × KDP and 0.1 × AGS at its maximum particle size. NaMg₄(VO₄)₃ could achieve phase matching at the fundamental frequency of 2090 nm but not at 1064 nm. LiMg₄(VO₄)₃ was unable to achieve phase matching at both the fundamental frequencies of 1064 nm and 2090 nm. In summary, we conducted a systematic investigation of quaternary compounds containing alkali and alkaline earth metal cations and VO₄ anions and performed a comprehensive characterization of the nonlinear optical properties of NaMg₄(VO₄)₃ and LiMg₄(VO₄)₃. The findings give insights into designing new vanadate-based compounds for the application of nonlinear optical materials in the future.

This study used DFT calculations to examine defect formation energy in potassium dihydrogen phosphate (KDP) with La substituting P. We found that neutral defects and the −3 charged state of La_P are more stable in the crystal. Lattice distortion analysis showed that defects disrupt the crystal structure. The H–O bond attached to the defect centre is shortened by 18.75–18.81%, resulting in HPO₄²⁻, which shares an H atom with the defect centre, becoming a hole trap and inducing more intrinsic defects. La_P point defects introduce new defect energy levels in the forbidden band, promoting defect energy level-assisted multiphoton absorption. By analysing the configuration coordinate diagram (CCD) and absorption spectrum, La^×_P introduces an absorption peak at 415 nm in the visible region, which is in accordance with the experimental results, showing a significant decrease in transmittance of La-doped KDP. The improvement in crystal transmittance after γ-ray irradiation is attributed to the transition of defects from La^×_P to , resulting in a red-shifted absorption spectrum in the ultraviolet region with a peak at 289 nm. This process produces a large Stokes redshift, which can lead to local melting of the crystal and greatly reduce the optical properties of the crystal.

As 3C-SiC can transform to other polytypes when the temperature is ≥2073 K, the current physical vapor transport (PVT) method can hardly grow wafer-grade 3C-SiC because its growth temperature is normally ≥2473 K. Therefore, solution growth is considered the most promising approach for the growth of wafer-grade 3C-SiC. However, few solution systems are available for growing 3C-SiC, which possess acceptable C solubilities and facilitate growth rate at growth temperatures below 2073 K. To address this challenge, this study designed a new Si–Cr–Nd–C solution that shows promise for the rapid growth of 3C-SiC at 1873 K, which is a significantly lower growth temperature than that required by most solution systems and the PVT method. The average C solubility in the SiC saturated Si-(40-x) mol% Cr-x mol% Nd alloy melts increased by 49.6 and 58.5 times at 1823 K and 1923 K, respectively, compared to the conventional Si-40 mol% Cr alloy melt without Nd. Notably, this study showed that the polytype of grown SiC crystal could transform from 4H-SiC to 100% 3C-SiC by adjusting the Nd content in the Si-(40-x) Cr-x Nd alloy melts, and the average growth rate of the SiC crystal at 1873 K was enhanced by 2.2 times by increasing the Nd content from 0 mol% to 20 mol%. Finally, rapid growth of the 3C-SiC single crystal is expected if the nucleation and growth of 3C-SiC with a single orientation can be controlled.

Arsenic(III) oxycompounds exhibit rich structural chemistry due to the presence of stereoactive lone electron pairs on arsenic and secondary As⋯O bonds that stabilize variable conformations of chains and rings in the case of oxyanions and layers or molecules in the case of oxide. These two features are also responsible for the fact that arsenic(III) oxide forms inclusion and intercalation compounds. In this Highlight article, the discovery and characterization of molecular arsenic(III) oxide inclusion compounds with hydrogen and helium are presented. Also, structural studies of As₂O₃ intercalation compounds with alkali metal halides and pseudohalides are thoroughly described. Finally, future research avenues in the field are presented, which have become more appealing due to the recent literature reports of extraordinary optical properties of arsenic(III) oxide intercalates.

The development of highly efficient photocatalysts for the reduction of CO₂ holds paramount importance in addressing the pressing global energy and environmental challenges. In this meticulously conducted study, we successfully fabricated a novel composite consisting of In-MOF and Bi₂MoO₆, and comprehensively investigated its photocatalytic performance in the context of CO₂ reduction. The formation of a heterojunction between the In-MOF and Bi₂MoO₆ facilitated efficient charge separation and transfer processes. The internal electric field present at the interface of the heterojunction drove the photogenerated electrons and holes to migrate in opposite directions, effectively mitigating their recombination rate. Consequently, a greater abundance of reactive species was available to participate in the CO₂ reduction reaction. The combined effects of enhanced light absorption and efficient charge separation culminated in a higher yield of CO and CH₄ compared to the individual components. This study provides some references and insights into the design and manufacture of high-performance photocatalysts.

BiSe is a layered topological insulator, which has not gained enough attention, while nanoscale topological insulator materials with high surface-to-volume ratio are promising candidates for advanced electronic devices. In this study, we report a facile chemical vapor deposition approach to synthesize high-quality BiSe nanowires and nanobelts, which exhibit the typical electrical transport property of topological insulators. Morphological and microstructural characterizations confirmed that single-crystalline BiSe nanowires and nanobelts with large surface area, near stoichiometric compositions and aspect ratios exceeding 1500 were formed. The growth of the BiSe nanowires and nanobelts was investigated in detail. It was found that appropriate growth temperature enabled optimal morphology, and an Au-catalyst-assisted vapor–liquid–solid mechanism was employed to control the quantity and quality of the products. The linear positive magnetoresistance at 2 K was observed in an individual BiSe nanowire; the results suggested the presence of massless Dirac fermions on the surface and gapless surface states, while a weak antilocalization effect was detected near 0 T magnetic field. This work provides a feasible route to synthesize one-dimensional BiSe nanostructures with well-defined morphology and reveals their intriguing magnetoresistance property.