Crystal Research and Technology最新文献

Single crystals of the organic nonlinear compound, (2E)-2-(3,4-Dimethoxybenzylidene)-3,4-dihydronaphthalen-1(2H)-one, is synthesized and grown through slow evaporation solution approach. The crystalline structure of the grown crystals is confirmed by single-crystal X-ray diffraction measurement. The fourier transform infrared (FT-IR)and Raman (FT-Raman) studies, along with potential energy distribution analysis, confirmed the vibrational contribution to each normal mode in the molecule. Thermal studies suggest that the chalcone molecule is thermally stable up to 187^°C. The bomb calorimeter yields a calorific value of 32405 J g⁻¹, higher than that of ethanol (28895 J g⁻¹), with a relative difference of 10.83%. The material's photoluminescence (PL) spectrum illustrates emission peaks in the green region, indicating that the molecule is suitable for manufacturing green LEDs. The combined theoretical and experimental ultraviolet-visible (UV–vis) absorption spectrum demonstrated an excellent transparency area and a small optical bandgap, emphasizing the material's potential use in window optical applications. The Z-scan technique analysis with a continuous-wave laser revealed significant self-defocusing and reverse saturable absorbance effects for closed and open apertures, respectively. The optical limiting threshold value of the compound is found to be 3.18 KJ cm⁻², and the computational nonlinear optical studies predict that the title compound has superior nonlinear characteristics compared to urea, thereby suggesting that the synthesized molecule is a promising candidate for nonlinear optical applications.

Compositional distribution in a Cd_0.9Zn_0.1Te_0.97Se_0.03 single crystal grown by crucible descending method is studied. Inductively coupled plasma optical emission spectroscopy (ICP-OES) and energy-dispersive X-ray spectroscopy (EDS) reveal a pronounced cationic accumulation at the ingot tail and anionic enrichment at the seed. The segregation of either Zn (k_Zn = 1.26) or Se (k_Se = 0.83) in the ingot is hardly influenced, despite the escalating concentration imbalances between the cations and anions along the ingot length. The composition variations through the ingot length are proposed to be the result of the non-uniform intermixing of the source materials caused by buoyancy during the stepped melting of elemental precursors prior to the crystal growth process. By using poly-crystalline Cd_0.9Zn_0.1Te_0.97Se_0.03 compound as a precursor, stoichiometric Cd_0.9Zn_0.1Te_0.97Se_0.03 single crystal ingots are achieved. The approach eliminates axial compositional gradients, yielding uniform detector-grade crystals. The work clarifies precursor synthesis as a critical factor in controlling compositional defects, offering a pathway to enhance crystal quality for radiation detection applications.

Antisolvent crystallization plays a vital role in pharmaceutical applications for managing drug crystal properties and polymorphism. This study introduces an innovative method to screen and isolate the metastable form II polymorph of d-Mannitol by optimizing ethanol-mediated antisolvent crystallization in aqueous systems. Ethanol concentration x, expressed as the mole fraction in the ethanol-water solvent mixture, is varied within the range 0.030 < x < 0.235 to investigate its effect on relative supersaturation, nucleation time, and crystal morphology. Results revealed that pure form I polymorph forms at lower ethanol levels (0.030 < x < 0.177) and low relative supersaturation (0.028 ˂ σ ˂ 0.595), while higher ethanol levels (x = 0.235) and relative supersaturation (σ = 1.454) yield pure form II polymorph. Intermediate conditions (ethanol levels 0.197< x < 0.217 and relative supersaturation 0.783 ˂ σ ˂ 1.097) produced a mixture of both forms. Morphological and structural analyses are conducted using optical microscopy and powder X-ray diffraction and thermal stability is assessed with differential scanning calorimetry. The study demonstrates ethanol's significant influence on polymorphic control and crystal properties through antisolvent crystallization.

In this study, Cobalt-doped strontium-nickel spinel ferrite samples, Co_xSr_0.5-xNi_0.5Fe₂O₄, x = 0.0, 0.2, and 0.4, are successfully synthesized via the sol-gel auto-combustion method for supercapacitor applications. X-ray diffraction (XRD) investigation verifies the generation of a highly crystalline, pure cubic spinel phase with face-centered cubic structure (Fd-3m space group). Fourier transform infrared spectroscopy (FTIR) validated the spinel structure through the observation of tetrahedral and octahedral metal–oxygen vibrations, with significant shifts in vibrational bands indicating successful Cobalt incorporation and cation redistribution. Field emission scanning electron microscopy (FESEM) images exposed the development of highly porous microstructures, with the x = 0.4 sample exhibiting the most uniform particle distribution and maximum porosity, beneficial for ion transport. Electrochemical analysis through cyclic voltammetry (CV) demonstrated that the x = 0.4 composition exhibited the largest enclosed area in the CV curves, indicating superior charge storage capability. Galvanostatic charge–discharge (GCD) measurements further confirmed that the x = 0.4 sample delivered the highest specific capacitance value of 12364.341 F g⁻¹ at lower current densities, highlighting its excellent electrochemical performance. Overall, the Co_xSr_0.5-xNi_0.5Fe₂O₄ sample with x = 0.4 composition emerges as the most promising candidate for high-performance supercapacitor electrodes, owing to its enhanced structural integrity, favorable porosity, and superior electrochemical behavior.

Pharmaceutical cocrystal technology has gained significant attention for its potential to enhance drug performance, particularly by improving solubility and bioavailability. Various preparation methods, characterization techniques, and screening tools are developed, including Hansen Solubility Parameters (HSP), COSMO-RS theory, Molecular Electrostatic Potentials (MEPs) for identifying hydrogen bond donors and acceptors, molecular dynamics simulations (MD), and machine learning (ML) techniques. These predictive tools facilitate virtual screening, expediting the discovery of promising cocrystals. In addition to solubility enhancement, cocrystal technology plays a crucial role in the drugs separation. Recent studies have explored enantiospecific and diastereomeric cocrystals, among other strategies, to improve the purity and efficacy of pharmaceutical compounds. These innovations offer valuable solutions for optimizing drug performance and further advancing the application and exploration of cocrystal technology in drug development.

Microwave has triggered huge interests for its efficient control of precipitation process. However, quantitative study of the coupling effect of thermal radiation and electromagnetic radiation of microwave on precipitation is limited. In this paper, the effect of microwave energy input on precipitation is studied experimentally and numerically at different temperature firstly. Sauter mean diameter of crystal products (d₃₂) is found to decrease with higher inflow concentration and increase with stronger microwave energy intensities (E) and higher temperature. In order to assess the influence of temperature and microwave energy input on nucleation, growth, aggregation, and crystal breakage, a population balance model coupled with empirical precipitation kinetics is performed. These kinetic parameters, including nucleation rate constant (k_n) and exponent (n), growth rate constant (k_g) and exponent (g), aggregation efficiency (Ψ_ag), and breakage rate constant (k_br) are fitted against experimental data. It is found that the electromagnetic effect of microwave can improve nucleation, crystal growth, and aggregation without breaking crystal product. Meanwhile, the thermal effect of microwave can enhance crystal growth, aggregation, and breakage while restrain nucleation. By choosing proper temperature, microwave provides a promising approach to produce larger crystals without additional risk of extra nucleation and crystal breakage.

Cellulose nanocrystals, as a natural material, have emerged as a research hotspot due to their unique chiral properties and excellent optical performance, which enable the formation of chiral liquid crystals. This literature review begins by introducing the fundamental characteristics of cellulose nanocrystals and their inherent liquid crystalline properties. Subsequently, the review elaborates on the optical properties of liquid crystal films which are formed through the self-assembly of cellulose nanocrystals, and highlights the latest studies that aim at enhancing these optical characteristics. Finally, the review delves into the extensive application potential of cellulose nanocrystals liquid crystal materials in fields such as anti-counterfeiting, sensors, cancer detection, and smart windows, achieved by harnessing functionalities including multi-layer optical responses, stress and humidity sensitivity, cell recognition capabilities, optical tuning, and thermal management. The innovative prospects for cellulose nanocrystals liquid crystal materials are vast, and future research is expected to further expand their applications in the field of liquid crystal technology.

CuFeS₂ nanocrystals have emerged as promising candidates for applications in photovoltaics, spintronics, and bioimaging due to their high absorption coefficients and tunable quantum confinement effects. This study focuses on the synthesis and characterisation of giant CuFeS₂/ZnS core/shell nanocrystals. The development of giant core/shell nanocrystals is a significant step toward addressing limitations such as poor luminescence and non-radiative recombination in CuFeS₂ nanocrystals. A novel ZnS shell growth protocol is employed to passivate surface defects and enhance photostability without introducing toxic heavy metals like cadmium. X-ray crystallography confirmed the formation of a sharp CuFeS₂/ZnS interface as well as improved crystallinity. Optical analysis reveals a bandgap as low as 0.5 eV, extending the reach of core/shell architectures into the near-infrared region. Transmission electron microscopy analysis highlights diverse morphologies and a well-defined core-shell structure, with an average size of 26 nm and a uniform ZnS shell of ∼3 nm. The study underscores the potential of CuFeS₂/ZnS nanocrystals as environmentally friendly, efficient, and scalable alternatives to traditional heavy-metal-based nanocrystals. By overcoming challenges in synthesis, this work introduces a novel class of giant nanocrystals with enhanced optical and structural properties, paving the way for advanced optoelectronic and biomedical applications.

This research examines the structural and ferroelectric characteristics of lanthanum-modified Bismuth Titanate (Bi₄Ti₃O₁₂) ceramics by co-doping with cobalt (Co³⁺) and iron (Fe³⁺). Structural refinement demonstrates that the La³⁺ substitution at Bi³⁺ significantly decreases titanium–oxygen bond lengths, augmenting the covalent character crucial for altering the ferroelectric response. Incorporating Co³⁺ and Fe³⁺ induces defects, causing a reduction in maximum polarization from around 10 µC cm⁻² to about 4.88 µC cm⁻². Structural examinations indicate an orthorhombicity of around 7.64×10⁻³ in the BLaT sample and 7.49×10⁻³ in the BLaT-FC2 sample, corresponding with their respective polarization tendencies. A defect pinning hindered the motion of the domain wall in BLaT-FC2, resulting in a constricted (P–E) hysteresis loop. Nevertheless, repeated electrical cycling enhances ferroelectric responses, allowing greater polarization alignment through progressive defect mitigation. As a result, structural defects and functional properties are dynamically interacting. The results highlight the significant impact of defect dynamics and structural changes on controlling the ferroelectric performance of Bi-based layered structure ceramics. This indicates that deliberate doping strategies and defect engineering can substantially enhance the reliability and effectiveness of ferroelectric materials for advanced electronic applications.