High Crystallinity Research Articles

Synthesis and characterization of La2O3-Al2O3-SiO2 glass ceramics for electronic substrate application

Fracture-resistant glass ceramic materials are critical for the advancement of electronic substrates. In this study, we successfully synthesized La2O3-Al2O3-SiO2 glass ceramics through the solid-state method. Comprehensive investigations were conducted into their phase composition, crystallization kinetics, microstructure, mechanical, thermal expansion, and microwave dielectric properties. The Kissinger, Ozawa, and Augis-Bennett methods are all appropriate for characterizing glass crystallization behavior. Mechanical testing results showed a sample with a composition of 45wt% La2O3-30wt% Al2O3-25wt% SiO2 exhibited superior properties attributed to its high crystallinity and dense microstructure, including the highest flexural strength (229.4MPa), Vickers hardness (8.78GPa), elastic modulus (118.7GPa), and fracture toughness (2.8MPa·m1/2). Notably, the fracture toughness values obtained using the VIF and SENB methods were significantly higher than those obtained using the EM method, and the validity of the data was confirmed by Weibull distribution analysis. These findings underscore the potential application of the developed glass ceramics in the field of electronic substrates.

Controllable synthesis of hydrogen-bonded organic framework encapsulated enzyme for continuous production of chiral hydroxybutyric acid in a two-stage cascade microreactor

Constructing a framework carrier to stabilize protein conformation, induce high embedding efficiency, and acquire low mass-transfer resistance is an urgent issue in the development of immobilized enzymes. Hydrogen-bonded organic frameworks (HOFs) have promising application potential for embedding enzymes. In fact, no metal involvement is required, and HOFs exhibit superior biocompatibility, and free access to substrates in mesoporous channels. Herein, a facile in situ growth approach was proposed for the self-assembly of alcohol dehydrogenase encapsulated in HOF. The micron-scale bio-catalytic composite was rapidly synthesized under mild conditions (aqueous phase and ambient temperature) with a controllable embedding rate. The high crystallinity and periodic arrangement channels of HOF were preserved at a high enzyme encapsulation efficiency of 59%. This bio-composite improved the tolerance of the enzyme to the acid-base environment and retained 81% of its initial activity after five cycles of batch hydrogenation involving NADH coenzyme. Based on this controllably synthesized bio-catalytic material and a common lipase, we further developed a two-stage cascade microchemical system and achieved the continuous production of chiral hydroxybutyric acid (R-3-HBA).

Dha Tab-COF filled PEBAX mixed matrix membranes for effective CO2/CH4 separation

Covalent organic skeletons (COFs) have been widely used in gas separation due to their excellent pore structure, high crystallinity, and high specific surface area. In this work, Dha Tab-COF was synthesized by solvothermal method and filled in polyether block polyamide (PEBAX) to form mixed matrix membranes (MMMs). Various characterization methods such as Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffractometry (XRD) were used to characterize the structure of Dha Tab-COF as well as the MMMs. The effects of operating pressure, operating temperature and the content of Dha Tab-COF particles on the CO2/CH4 separation performance of the membranes were investigated. The best separation performance with a CO2 permeability of 295.8 Barrer and a CO2/CH4 selectivity of 21.6 was achieved when the Dha Tab-COF content is 2 wt%, which were 45.7% and 108.1% higher than that of the pure PEBAX membrane, respectively.

Proposal of a Biobased and Biodegradable Polymer as a Hot Embossing Substrate for Holographic Security Marks Fabrication

ABSTRACTThe alarming increase in counterfeiting has determined a more intensive application of authentication solutions such as holographic security marks. Polycarbonate or polymethyl methacrylate currently used in the hot embossing process to produce security marks are discarded as non‐biodegradable waste after utilization. For the first time, poly(lactic acid) (PLA) was studied here as a hot‐embossing substrate to imprint a micro‐relief containing diffractive gratings, as a stage in the fabrication of holographic security marks. Four PLA grades, which differ by crystallinity and mechanical properties, were used to define the suitability of PLA for hot embossing. The 3D topography of embossed micro‐relief in PLA plates was investigated by quantitative phase imaging, scanning electron microscopy, and atomic force microscopy (AFM). The analyses showed that a high crystallinity and a low d‐lactide content of PLA render the hot‐embossing process more difficult and decrease the quality of the imprinted micro‐relief. The average height of the micro‐relief and the difference in height values, which were determined by AFM, allowed the ranking of the PLA grades according to the quality of the diffracted image. The possibility of recycling the embossed PLA substrate several times before composting was also demonstrated in this work. The variation of the mechanical properties, thermal stability, melting, and crystallization behaviors after each recycling cycle has shown that PLA can be reprocessed six times without significant damage to the properties. This study demonstrated that PLA can replace petroleum‐based polymers in the fabrication of holographic security marks and its suitability for a plethora of optoelectronics applications.

Green utilization of sorghum straw by coupled hydrothermal pretreatment and cellulase hydrolysis for bacillomycin D production under fed-batch mode

The present work explored the coupled hydrothermal pretreatment and cellulase hydrolysis (HPCH) for production of bacillomycin D from sorghum straws by Bacillus subtilis NS-174. The results indicated that HPCH treated sorghum straws had weaker absorption, heavier mass loss and higher crystallinity, and displayed loose and destructive fiber structures. Degradation of hemicellulose and lignin contributhed to yielding glucose and 68.94g/L of glucose was obtained in HPCH treated hydrolysate. High level of glucose in pretreated sorghum straw hydrolysate was helpful for improving bacillomycin D production. When performed by 3rd round (feeding at 144h) fed-batch fermentation, bacillomycin D production and production rate were obtained to be 2351.07mg/L and 113.36mg/L.h in B. subtilis NS-174, respectively.

Controlling the Crystalline Quality and Yield of Single‐Walled Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Synthesis

AbstractCarbon nanotubes (CNTs) were synthesized by floating catalyst chemical vapor deposition (FCCVD) reactions. The complicated processing parameters that included a precursor solution composition, reaction temperature, flow rate of the carrier gas, weak oxidants, and injection rate of the precursor solution were controlled to synthesize single‐walled carbon nanotubes (SWCNTs) during the reaction process. The effects of the processing parameters were analyzed with respect to the formation of SWCNTs, yield, and the crystallinity in the CNTs structure. The SWCNTs were characterized by the Raman spectroscopy, scanning electron microscope, high‐resolution transmission electron microscopy, and thermogravimetric analysis. A high reaction temperature, high H2 flow rate, low injection rate of solution precursor, and low concentrations of iron catalysts in the reaction were important factors to improve the crystalline quality of the SWCNTs. The purity of the initial product grown by the standard process was more than 90 wt %, with a yield of 0.5 g/h. The average G/D ratio of the initial product was 178, and it had a distinct RBM peak. HRTEM confirmed that the synthesized SWCNTs had high purity and crystallinity. The SWCNTs could be tunable to meet a particular application by varying the reaction conditions.

Amino acid assisted-construction of 2D-hierarchical MFI zeolites for adsorption of rhodamine B

Hierarchical and two-dimensional (2D) zeolites have drawn much attention in catalysis and separation process due to their fast mass transfer. However, the facile manipulation in controllable mesopore volumes and morphologies for hierarchical nanozeolites is full of challenges. Herein, a facile strategy is presented for the synthesis of single-crystalline 2D hierarchical MFI zeolite nanosheets (HNSs) with tunable mesopore volumes through the amino acid-assisted crystallization of nucleated amorphous silicon precursors (NASPs). The tailored synthesis of HNSs with controllable aspect ratios ((Lc + La)/Lb), b-axis thicknesses (a few tens of nanometers) and mesopore volumes is achieved by adjusting the preparation of the NASPs and the amount of amino acid in the synthesis mixture. The HNSs exhibit large BET surface area (>400 m2/g), high micropore volume (0.16–0.18 cm3 g−1) as well as rich mesopore volume (>0.10 cm3 g−1), indicating the high crystallinity of the hierarchical zeolite nanosheets. Specially, the higher adsorption capability and faster adsorption rate for the dye (Rhodamine B) adsorption demonstrate the excellent performance of the hierarchical zeolite nanosheets, which exhibit the maximum adsorption capacity of 115.7 mg g−1. The controllable manipulation of mesoporous volumes and morphologies in MFI zeolites represents a significant contribution to the field of zeolite microstructure engineering.

Impact of tetracyanoethylene plasticizer on PEO based solid polymer electrolytes for improved ionic conductivity and solid-state lithium-ion battery performance

Poly(ethylene oxide) is a promising material for solid-state lithium batteries due to its safety, ease of processing, and compatibility with lithium. However, conventional linear PEO falls short of practical requirements due to its limited ionic conductivity, a consequence of the high crystallinity of its ethylene oxide chains. This crystallinity hinders the movement of lithium ions, limiting its performance in solid-state battery applications. In this study, we successfully prepared the plasticized solid polymer electrolytes (PSPEs) based on poly(ethylene oxide) (PEO)/tetracyanoethylene (TCE) complexed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and studied the effect of TCE on structural, mechanical, electrical and electrochemical properties of PSPEs. The addition of tetracyanoethylene effectively disrupts the crystallinity of the PEO matrix, as confirmed by X-ray diffraction analysis. The addition of TCE also enhanced the elongation-at-break of the PEO12-LiTFSI system, indicating improved flexibility. Consequently, the ionic conductivity of the SPEs increases with increasing tetracyanoethylene content, reaching a maximum of 1.14 × 10−4 S/cm at 25 °C for the electrolyte containing 30 wt% of tetracyanoethylene. Furthermore, the plasticized SPEs exhibit a wide electrochemical stability window, as determined by linear sweep voltammetry. Solid-state battery tests demonstrate a high initial discharge capacity of 143.5 mAhg−1 at 0.1C along with good cycling performance.

Biomimetic Structural Hydrogels Reinforced by Gradient Twisted Plywood Architectures.

Naturally structural hydrogels such as crustacean exoskeletons possess a remarkable combination of seemingly contradictory properties: high strength, modulus, and toughness coupled with exceptional fatigue resistance, owing to their hierarchical structures across multiple length scales. However, replicating these unique mechanical properties in synthetic hydrogels remains a significant challenge. This work presents a synergistic approach for constructing hierarchical structural hydrogels by employing cholesteric liquid crystal self-assembly followed by nanocrystalline engineering. The resulting hydrogels exhibit a long-range ordered gradient twisted plywood structure with high crystallinity to mimic the design of crustacean exoskeletons. Consequently, the structural hydrogels achieve an unprecedented combination of ultrahigh strength (46±3MPa), modulus (496±25MPa), and toughness (170±14MJ m-3), together with recorded high fatigue threshold (32.5kJ m-2) and superior impact resistance (48±2kJ m-1). Additionally, through controlling geometry and compositional gradients of the hierarchical structures, a programmable shape morphing process allows for the fabrication of complex 3D hydrogels. This study not only offers valuable insights into advanced design strategies applicable to a broad range of promising hierarchical materials, but also pave the ways for load-bearing applications in tissue engineering, wearable devices, and soft robotics.

A holocellulose air filter with highly efficient formaldehyde adsorption prepared via low temperature pulping and partial dissolving from corn stalks

Emissions of particulate matter (PM) originating from industrial and agricultural incineration had emerged as a significant public health concern. Furthermore, the considerable annual production of straw remains underutilized, particularly in China. In this study, we proposed a novel approach for holocellulose air filter production from corn stalks via low-temperature anthraquinone pulping, partial dissolving, and high-speed shear-induced regeneration. About 61.40–78.23 % of hemicellulose in corn stalks was retained in holocellulose, furthermore, the delignification rate was up to 81.63–92.51 % after low temperature (<100 °C) alkaline exactment. Subsequently, holocellulose air filters (RHF) was prepared through regeneration with high-speed shear induced (25,000 rpm) and freeze-drying. The final air filters contained approximately 8.56–12.4 % hemicellulose, exhibiting a substantial adsorption capacity for low molecules such as formaldehyde. The results revealed remarkably low PM2.5 penetration ratio (0.12 %) and pressure drop (14.3 Pa) of the air filter, while exhibiting a remarkable formaldehyde adsorption capacity of 54.5 mg/g. Moreover, the characters of high crystallinity index and robust micro/nano-structure of regenerated cellulose were obtained. This study introduced an innovative and facile strategy for gaseous formaldehyde adsorption and introduced novel solutions for agricultural waste utilization.

Preparation of efficient all-inorganic perovskite solar cells from large grain via 1-heptanamine stabilised CsPbI2Br nanoparticles with NH4SCN additive

CsPbI2Br is a potential material for perovskite solar cells (PSCs) due to its better thermal stability and high efficiency. Centrifugal deposition for film formation greatly simplifies the steps of the conventional anti-solvent spin coating method, but there are still problems hindering progress, such as small grain size and poor photoelectric performance. In this work, NH4SCN was introduced as an additive during the preparation of heptylamine (C7H17N) stabilised CsPbI2Br nanoparticles (NCs) and the films were prepared by centrifugal deposition. The results show that the low melting temperature compounds which formed by thiourea from NH4SCN decomposition during annealing and unreacted PbX2 would link the small grains together by melting and flowing; after PbX2 precipitation and reaction with CsX, the grain size was significantly increased by about 95 % compared to that of the untreated film. Due to large grains, less defects and high crystallinity, the final power conversion efficiency and fill factor reached 12.25 % and 0.70, respectively.

A Fully Saturated Covalent Organic Framework.

We report the design and synthesis of the first aliphatic covalent organic framework (COF), NUS-119, and its subsequent conversion to NUS-120, marking the first fully saturated COF. NUS-119 is built by imine-linkages exhibiting high crystallinity and porosity, achieved by using a Lewis acid as a reaction modulator to circumvent compatibility issues between the Brønsted acid and the strong basic monomer. The structure was successfully solved using 3D microelectron diffraction (microED) techniques. NUS-119 and NUS-120 demonstrated remarkable catalytic performance in base-catalyzed Knoevenagel condensation reactions, exhibiting high conversion rates, excellent size selectivity, and good recyclability. This work advances the understanding of COF materials and paves the way for future research and applications.

Eco-friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles for enhanced dye-sensitized solar cells utilizing oxalis Corniculata leaf extract

An environmentally friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles (NPs) was developed using Oxalis Corniculata leaf (OCL) extract to enhance the performance of dye-sensitized solar cells (DSSCs). The as-synthesized NPs were annealed at 600 °C to improve their crystallinity. X-ray diffraction and field-emission scanning electron microscopy revealed high crystallinity and a sub-100 nm spherical morphology. Annealing reduced the NP size from ∼85 nm to ∼45 nm and decreased the bandgap from 4.97 eV to 4.62 eV, enhancing low-energy photon absorption. Fourier-transform infrared spectroscopy showed changes in the chemical bonding environment, with a higher presence of dangling bonds in the as-prepared NPs compared to the 600 °C-annealed NPs, likely due to the OCL extract. Photoluminescence spectra confirmed strong red emission peaks at 580 nm and 612 nm, with a slight reduction in the full width at half maximum of the electric dipole transition after annealing. Integrating these NPs into TiO₂ matrices in DSSCs improved power conversion efficiency to 8.58%, outperforming both as-prepared NPs (6.88%) and bare TiO₂ cells (5.05%). This green synthesis approach offers a sustainable pathway for slightly enhancing performance of photovoltaic devices, with additional potential for UV-shielding applications when incorporated into PVA films.

Giant piezoelectricity in antiferromagnetic CrS2 and CrSe2 monolayers

Abstract Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDs), have garnered significant attention in the nanoscale piezoelectric field due to their high crystallinity and ability to withstand large strains. Through density-functional theory calculations, we have discovered that monolayer H-phase CrS2 and CrSe2 exhibit antiferromagnetic semiconducting properties, in contrast to the previously held belief that they were nonmagnetic (NM) semiconductors. While the piezoelectric coefficients of NM CrS2 and CrSe2 are comparable to those of MoS2, their antiferromagnetic ground states demonstrate significantly enhanced piezoelectric coefficients ( d 11 ) of 27.66 pm V−1 and 52.36 pm V−1, respectively. These values exceed that of MoS2 by an order of magnitude, marking the highest recorded for TMD materials and the highest in 2D magnetic materials to date. The greatly enhanced piezoelectric responses in the antiferromagnetic states of CrS2 and CrSe2 compared to their NM states arise from three primary factors. Firstly, the displacement of the Wannier center under strain is more pronounced in the antiferromagnetic state, leading to a greater change in dipole moment (enhanced clamped-ion contribution). Secondly, there is a heightened polarization change due to internal atomic distortions (internal-strain term) in response to macroscopic strain in the antiferromagnetic state. Thirdly, the material undergoes a softening of the elastic coefficient in its antiferromagnetic state. These findings open new avenues for designing high-performance piezoelectric and magnetic multifunctional materials.

Preparation and Formation Mechanism of β-SiC Coatings Using a SiCl4-CH4-H2-N2 System.

The mechanism of β-SiC preparation via chemical vapor deposition (CVD) of the SiCl4-CH4-H2-N2 system remains unclear. Consequently, the change of molar Gibbs free energy of the CVD β-SiC chemical reaction in the SiCl4-CH4-H2-N2 system has been studied by the Helsinki Software Corporation (HSC) Chemistry code for the first time. The role of nitrogen in the reaction was confirmed. Seven potential reaction pathways of CVD β-SiC were presented, and the thermodynamic equilibrium components of each reaction were calculated systematically. The most viable reaction pathway and corresponding optimal temperature range for CVD β-SiC were determined. In addition, a kinetic study of CVD β-SiC was conducted. The microscopic morphology and crystal structure of β-SiC coatings prepared on the graphite surface at different temperatures were charactered by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, etc. Ultimately, through SEM, XRD, and Raman observation, uniform and dense β-SiC coatings with fine grains and high crystallinity were successfully obtained. Furthermore, large β-SiC-coated graphite trays with diameters of 230 and 465 mm were prepared by CVD using the SiCl4-CH4-H2-N2 system, and the average thickness of β-SiC was about 100.6 μm. This study provides a theoretical basis and technical recommendations for the fabrication of SiC-coated graphite trays used in metal-organic chemical vapor deposition (MOCVD) equipment.

Encapsulation Engineering of Sulfur into Magnesium Oxide for High Energy Density Li-S Batteries.

This study addresses the persistent challenge of polysulfide dissolution in lithium-sulfur (Li-S) batteries by introducing magnesium oxide (MgO) nanoparticles as a novel additive. MgO was integrated with sulfur using a scalable process involving solid-state melt diffusion treatment followed by planetary ball milling. XRD measurements confirmed that sulfur (S8) retains its orthorhombic crystalline structure (space group Fddd) following the MgO incorporation, with minimal peak shifts indicating slight lattice distortion, while the increased peak intensity suggests enhanced crystallinity due to MgO acting as a nucleation site. Additionally, Raman spectroscopy demonstrated sulfur's characteristic vibrational modes consistent with group theory (point group D2h) and highlighted multiwalled carbon nanotube (MWCNT's) D, G, and 2D bands, with a low ID/IG ratio (0.47), which indicated low defects and high crystallinity in the prepared cathode. The S-MgO composite cathode exhibited superior electrochemical behavior, with an initial discharge capacity (950 mA h g-1 at 0.1 C), significantly improved compared to pristine sulfur's. The presence of MgO effectively mitigated the polysulfide shuttle effect by trapping polysulfides, leading to enhanced stability over 400 cycles and the consistent coulombic efficiency of over 99.5%. After 400 cycles, EDS and SEM analyses confirmed the structural integrity of the electrode, with only minor fractures and slight sulfur content loss. Electrochemical impedance spectroscopy further confirmed the enhanced performance.

Solid-state synthesis of aluminophosphate-based zeotypes from conventional amorphous precursors: Strategy and catalytic performance

Exploring novel strategies for the preparation of zeolitic materials with high performance continues to be of great significance. Here we report a general solid-state approach for fabricating aluminophosphate (AlPO)-based zeotypes by directly calcining conventional amorphous precursors at 300 °C for just 30 min. Accordingly, AEL, AFI, LTA and CHA types of AlPO-based zeotypes with high crystallinity and similar textural properties to those of counterparts made by established synthesis approaches have been synthesized. As a demonstration, the catalytic performance of Mg-substituted AlPO-11 (S-MgAlPO-11) in hydroisomerization of n-hexadecane (n-C16) was also investigated. Compared with the Pt supported on conventional MgAlPO-11 (Pt/C-MgAlPO-11) catalyst, the Pt/S-MgAlPO-11catalyst exhibits higher isomerized (87 % vs. 84 %), multi-branched C16 (48 % vs. 30 %) yields and superior reaction stability, attributing to the improved diffusion property and appropriate metal-acid balance. This strategy provides an efficient approach to synthesis promising zeolitic catalysts for industrial applications.

Hierarchical core-shell ZIF-11@ZIF-8 composite nanocatalyst for high-yield simultaneous transesterification-esterifications of sunflower oil to produce biodiesel

Decreasing the mass transfer resistance is a promising technique to prepare an efficient catalyst for improving biomass macromolecules conversion in biodiesel production. In this study, hierarchical core–shell composite nanocatalysts were prepared through a solvothermal technique using zeolitic imidazolate framework-8 (ZIF-8) and ZIF-11 metal–organic frameworks (MOFs). The nanocatalysts were characterized by XRD, FT-IR, BET, FE-SEM, EDS, XPS, TEM, NH3-TPD, and CO2-TPD analyses. The results showed high crystallinity, high surface area (1446.86 m2/g), high pore volume (0.65 cm3 g−1), and mesoscale pore size (2.37 nm). Furthermore, TEM images confirmed the formation of core–shell structure for the composites. The catalytic activity was evaluated in the transesterification of sunflower oil at different operating conditions. The highest biodiesel yield (96.4 %) and full free fatty acid (FFA) conversion were obtained over the ZIF-11@ZIF-8 nanocatalyst at the optimum operating conditions: 120 °C, catalyst concentration of 8 wt%, methanol to oil ratio of 40:1, and 10 h. The ZIF-11@ZIF-8 nanocatalyst showed high thermal and chemical stability after several sequence cycles, leading to high reusability.

Route to Enhancing Remote Epitaxy of Perovskite Complex Oxide Thin Films.

Remote epitaxy is taking center stage in creating freestanding complex oxide thin films with high crystallinity that could serve as an ideal building block for stacking artificial heterostructures with distinctive functionalities. However, there exist technical challenges, particularly in the remote epitaxy of perovskite oxides associated with their harsh growth environments, making the graphene interlayer difficult to survive. Transferred graphene, typically used for creating a remote epitaxy template, poses limitations in ensuring the yield of perovskite films, especially when pulsed laser deposition (PLD) growth is carried out, since graphene degradation can be easily observed. Here, we employ spectroscopic ellipsometry to determine the critical factors that damage the integrity of graphene during PLD by tracking the change in optical properties of graphene in situ. To mitigate the issues observed in the PLD process, we propose an alternative growth strategy based on molecular beam epitaxy to produce single-crystalline perovskite membranes.

Synthesis and structure of a non-van-der-Waals two-dimensional coordination polymer with superconductivity

Two-dimensional conjugated coordination polymers exhibit remarkable charge transport properties, with copper-based benzenehexathiol (Cu-BHT) being a rare superconductor. However, the atomic structure of Cu-BHT has remained unresolved, hindering a deeper understanding of the superconductivity in such materials. Here, we show the synthesis of single crystals of Cu3BHT with high crystallinity, revealing a quasi-two-dimensional kagome structure with non-van der Waals interlayer Cu-S covalent bonds. These crystals exhibit intrinsic metallic behavior, with conductivity reaching 103 S/cm at 300 K and 104 S/cm at 2 K. Notably, superconductivity in Cu3BHT crystals is observed at 0.25 K, attributed to enhanced electron-electron interactions and electron-phonon coupling in the non-van der Waals structure. The discovery of this clear correlation between atomic-level crystal structure and electrical properties provides a crucial foundation for advancing superconductor coordination polymers, with potential to revolutionize future quantum devices.