Crystal Surface Properties Research Articles

Development of calcium phosphate cement composed of silica-modified hydroxyapatite, cerium oxide, and silica as an osteoporotic bone filler

Calcium phosphate cement (CPC), composed of silica-modified hydroxyapatite (HA-SiO2), cerium oxide (CeO2), and silica (SiO2), was developed as an osteoporosis bone filler. The effect of CeO2 and SiO2 content on the CPC's properties, such as crystal parameters, surface properties, antibacterial activity, and toxicity properties, were studied. HA-SiO2 was prepared using the sol-gel method, while CeO2 was prepared using the precipitation method. HA in HA-SiO2 has crystal properties similar to pure HA. Synthesized CeO2 contains Ce3+ and Ce4+ ions with Ce3+/Ce4+ = 0.34. Computational calculation predicted that the CeO2 (111) surface and glycine molecule interaction was categorized as chemisorption. Moreover, CeO2 has antibacterial activity toward Escherichia coli and Staphylococcus aureus. Combining HA-SiO2 and CeO2 did not change the adsorption-desorption isotherm curve type, but slightly decreased the surface area, total pore volume, and average pore. Increasing the percentage of CeO2 and adding 10 % SiO2 (w/w) affected the particle's size and CeO2 distribution. However, CPC lost antibacterial activity toward Staphylococcus aureus but adding 10 % SiO2 (w/w) increases the bacterial activity toward Escherichia coli close to that of pure CeO2. The MTT assay using pre-osteoblast MC3T3E1 cells showed that the CPC has IC50 = 4227 μg/ml or is nontoxic.

Effect of N2-H2 remote plasma nitridation temperature on surface properties of Te-doped GaSb crystals

GaSb is regarded as one of the most promising near-infrared optoelectronic materials in recent years. However, due to the ease of natural oxidation of GaSb, the surface will promptly form a thick oxide layer which is highly resistant to removal, resulting in detrimental interface defects and higher surface state density. Although studies have demonstrated the feasibility of plasma for removing oxide, the ultra-high vacuum is necessary for complete removal, which poses challenges for commercial applications. Herein, we optimized the nitrogen plasma passivation process for Te-doped GaSb, combining remote plasma source with Atomic Layer Deposition (ALD) in-situ annealing to modify GaSb (001) surface, which approaches non-damaging treatment. The temperature during passivation will affect nitrogenation on GaSb surface, result in enrichment of metallic Sb when reaching 573 K, and impact emission efficiency. By setting the passivation temperature at 523 K and combining with in-situ annealing, the photoluminescence (PL) efficiency of GaSb has doubled. This demonstrates the validity of low-temperature nitrogen passivation in improving surface state and reducing defect density on GaSb.

Green auto-combustion synthesis of SrNiO3/NiO/SrCO3 ferromagnetic-nanocomposites in the presence carbohydrate sugars and their application as photocatalyst for degradation of water-soluble organic-pollutants

This study utilized an environmentally-friendly method to synthesize SrNiO3/NiO/SrCO3 nanocomposites using glucose and lactose as fuels. A variety of fuel concentrations were investigated in order to determine their effects on SrNiO3/NiO/SrCO3 nanocomposites from both a pure and a morphological perspective. Various physiochemical techniques were employed to examine the crystal structure, morphology, optical, magnetic, and surface properties of the synthesized nanoparticles. These techniques included X-ray diffract, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometers, and Brunauer-Emmett-Tellers. The band gap of the as-synthesized nanoparticles was determined to be 2.5eV, suggesting that they are capable of acting as a photocatalyst under sunlight-like conditions. The photocatalytic activity of SrNiO3/NiO/SrCO3 nanocomposites was evaluated against Methyl orange (MO) and Methyl violet (MV), and the mechanism of the photocatalyst was investigated using EDTA, benzoic acid, and benzoquinone as scavengers. A comparison of photocatalytic activity in UV and sun-like light showed that maximum degradation (92%) and (84.8%) were related to degradation of MO (20 ppm) and MV in 60min, respectively. The results indicate that SrNiO3/NiO/SrCO3 nanocomposites synthesized using the auto combustion method may serve as a promising photocatalyst for the degradation of organic pollutants in the environment within a short period of time.

A Visual Representation for Accurate Local Basis Set Construction and Optimization: A Case Study of SrTiO3 with Hybrid DFT Functionals

The linear combination of atomic orbitals (LCAO) method is advantageous for calculating important bulk and surface properties of crystals and defects in/on them. Compared to plane wave calculations and contrary to common assumptions, hybrid density functional theory (DFT) functionals are actually less costly and easier to implement in LCAO codes. However, choosing the proper basis set (BS) for the LCAO calculations representing Guassian-type functions is crucial, as the results depend heavily on its quality. In this study, we introduce a new basis set (BS) visual representation, which helps us (1) analyze the collective behavior of individual atoms’ shell exponents (s, p, and d), (2) better compare different BSs, (3) identify atom-type invariant relationships, and (4) suggest a robust method for building a local all-electron BS (denoted as BS1) from scratch for each atom type. To compare our BS1 with the others existing in the literature, we calculate the basic bulk properties of SrTiO3 (STO) in cubic and tetragonal phases using several hybrid DFT functionals (B3LYP, PBE0, and HSE06). After adjusting the exact Hartree–Fock (HF) exchange of PBEx, HSEx, and the state-of-the-art meta-GGA hybrid r2SCANx functionals, we find the r2SCAN15 and HSE27 for BS1, with the amount of exact HF exchange of 0.15 and 0.27, respectively, perform equally well for reproducing several most relevant STO properties. The proposed robust BS construction scheme has the advantage that all parameters of the obtained BS can be reoptimized for each new material, thus increasing the quality of DFT calculation predictions.

Novel magnetic iron oxide-dextran sulphate nanocomposites as potential anticoagulants: Investigating interactions with blood components and assessing cytotoxicity

Examining the critical role of anticoagulants in medical practice, particularly their central function in preventing abnormal blood clotting, is of the utmost importance. However, the study of interactions between blood proteins and alternative anticoagulant nano-surfaces is still understood poorly. In this study, novel approach involving direct functionalisation of magnetic iron oxide nanoparticles (MNPs) as carriers with sulphated dextran (s-dext) is presented, with the aim of evaluating the potential of magnetically-responsive MNPs@s-dext as anticoagulants. The physicochemical characterisation of the synthesised MNPs@s-dext includes crystal structure analysis, morphology study, surface and electrokinetic properties, thermogravimetric analysis and magnetic properties` evaluation, which confirms the successful preparation of the nanocomposite with sulfonate groups. The anticoagulant potential of MNPs@s-dext was investigated using a standardised activated partial thromboplastin time (APTT) test and a modified APTT test with a quartz crystal microbalance with dissipation (QCM-D) which confirmed the anticoagulant effect. Time-resolved solid-liquid interactions between the MNPs@s-dext and model blood proteins bovine serum albumin and fibrinogen were also investigated, to gain insight into their hemocompatibility, and revealed protein-repellence of MNPs@s-dext against blood proteins. The study also addressed comprehensive cytotoxicity studies of prepared nanocomposites, and provided valuable insights into potential applicability of MNPs@s-dext as a promising magnetic anticoagulant in biomedical contexts.

Tailoring surface defects to enhance PBX surface adhesion through autologous surface molecular reconfiguration

Surface modification of explosive crystals is crucial for enhancing the performance of explosives, particularly polymer-bonded explosives (PBXs). Traditional methods to boost mechanical properties in PBXs, such as surface coating, often encounter issues like complex operations, inadequate adhesion, and impurity introduction. In this paper, direct surface modification via the assembly-disassembly of NH…O hydrogen bond synthon was presented for enhancing interfacial adhesion. Using the autologous surface molecular reconfiguration resulting from hydrogen bond synthon, diverse surface defects were introduced on crystals. The notable surface alterations are influenced by concentration and suspension time. The crystal surface with irregular surface morphology adheres more strongly to the binders and its PBXs were increased the elastic recovery by 28.9 % compared to the raw material. Furthermore, this technique of altering crystal surface properties by introducing surface defects not only maintains the purity of the particles but simplifies the preparation process, making it efficient and environmentally friendly.

Effect of a Magnetic Field on the Surface Structure and Properties of Germanium Single Crystals

Effect of a Magnetic Field on the Surface Structure and Properties of Germanium Single Crystals

Modulation of ADN Crystal Surface Properties by Additives

Modulation of ADN Crystal Surface Properties by Additives

Catalytic Acetone Oxidation over MnOx Catalysts: Regulating Their Crystal Structures and Surface Properties

This study investigates the catalytic oxidation of acetone by different crystal phases of MnO2 prepared via different methods. Compared with β-MnO2 and γ-MnO2, α-MnO2 exhibited superior catalytic activity. Moreover, as replacements for traditional hydrothermal methods and air calcination, the use of microwave hydrothermal methods and N2 calcination significantly enhanced the catalytic performance of the MnO2 catalyst. The optimal catalyst, MnO2-WN (α-MnO2 synthesized via microwave hydrothermal method and N2 calcination), converted 100% of 100 ppm acetone below 150 °C, with the CO2 yields reaching 100%. Further, the stability of the catalyst and its potential for other volatile organic compounds (VOCs) were also determined. The experimental data demonstrated that its outstanding activity primarily stemmed from the improved preparation method, enhancing the specific surface area of the catalyst, optimizing the pore structure, improving the redox performance, and generating more acidic sites and active oxygen species, thereby creating a synergistic effect. Finally, the reaction pathway of acetone oxidation on the catalyst surface has been explored. This work provides a new perspective for developing economically efficient MnOx catalysts for removing VOCs.

Perovskite Single Crystals with Self‐Cleaning Surface for Efficient Photovoltaics

AbstractMetal halide perovskite single crystals are promising for diverse optoelectronic applications. As a universal issue of solution‐grown perovskite single crystals, surface contamination causes adverse effect on material properties and device performance. Herein, learning from the self‐cleaning effect of lotus leaf, we address the surface contamination issue by introducing an amphiphilic long‐chain organic amine into the perovskite crystal growth solution. Self‐assembly of CTAC provides a hydrophobic crystal surface, inducing spontaneous removal of residual growth solution, which results in clean surface and better optoelectronic properties of perovskite single crystals. An impressive efficiency of 23.4 % is obtained, setting a new record for FAxMA1‐xPbI3 single‐crystal perovskite solar cells (PSCs). Moreover, our strategy also applies to perovskite single crystals with different morphology and composition, which may contribute to improvement of other single‐crystal perovskite optoelectronic devices.

Perovskite Single Crystals with Self-Cleaning Surface for Efficient Photovoltaics.

Metal halide perovskite single crystals are promising for diverse optoelectronic applications. As a universal issue of solution-grown perovskite single crystals, surface contamination causes adverse effect on material properties and device performance. Herein, learning from the self-cleaning effect of lotus leaf, we address the surface contamination issue by introducing an amphiphilic long-chain organic amine into the perovskite crystal growth solution. Self-assembly of CTAC provides a hydrophobic crystal surface, inducing spontaneous removal of residual growth solution, which results in clean surface and better optoelectronic properties of perovskite single crystals. An impressive efficiency of 23.4 % is obtained, setting a new record for FAx MA1-x PbI3 single-crystal perovskite solar cells (PSCs). Moreover, our strategy also applies to perovskite single crystals with different morphology and composition, which may contribute to improvement of other single-crystal perovskite optoelectronic devices.

Effect of molybdenum valence in low Mo/Sn ratio catalysts for the oxidation of methanol to dimethoxymethane

A series of Mo/Sn (1:20, molar ratio) catalysts were prepared by two-step hydrothermal synthesis method, and the effect of calcination temperature of tin precursors on the reaction performance of methanol oxidation to dimethoxymethane (DMM) was investigated. The crystal structure, surface properties, redox property and valence change of molybdenum species of the catalyst were characterized by XRD, Raman, FT-IR, XPS, NH3-TPD and H2-TPR. The results showed that Mo1Sn20-600°CSn catalyst exhibited better performance than other catalysts, achieving DMM selectivity of 90% with methanol conversion of 30% at 140 °C. From the characterization results, the surface properties of the tin precursors affected the structure of catalyst, the degree of molybdenum oxide dispersion and valence of molybdenum species, and further influenced the performance of the catalysts. The high temperature calcination of tin precursors is more favorable for the generation of Mo6+ in the Mo1Sn20 catalyst.

Synthesis and performance of novel fluoro acrylate polymer containing rigid cyclohexane group as a mesogenic core

Fluorine-containing liquid crystal polymers have excellent hydrophobic stability, making them attractive for use in the field of stable hydrophobic coatings. To improve the hydrophobic stability of fluoropolymers, a novel fluoro acrylate monomer (FAM) containing a rigid cyclohexane structure was simply synthesized using isophorone diisocyanate (IPDI), hydroxyethyl methacrylate (HEMA), and perfluorohexylethanol (S104) as raw materials and its homopolymer (PFAM) was prepared by radical solution polymerization. The structure, liquid crystal behavior, thermal properties, hydrophobic properties, and surface properties of FAM or PFAM and a reference substance, dodecafluoroheptyl methacrylate (DFMA) and its homopolymer (PDFMA), were studied using various techniques including FT-IR, NMR, GPC, XRD, POM, DSC, TGA, XPS, AFM, and static/dynamic contact angle measurements. The results indicate that FAM and PFAM are thermally liquid crystalline. PFAM's thermal stability is higher than that of PDFMA. The presence of a rigid cyclohexane structure facilitates the dense distribution of fluorocarbon chain tails of the homopolymer and also prevents surface reconstruction when the homopolymer comes into contact with polar liquids, resulting in improved hydrophobicity and hydrophobic stability. Thus, this study provides a straightforward method for the synthesis of fluoro acrylates with surface stability, highlighting their potential application in hydrophobic coatings.

The Rational Design of Low‐Barrier Fluorinated Aluminum Substrates for Anode‑Free Sodium Metal Battery

AbstractAnode‐free Na metal batteries are acclaimed for their high energy densities achieved through current collectors in situ plated with Na metal in the absence of active negative materials. The advancement of these devices hinges on the development of affordable current collectors for effective Na deposition and the design of advanced electrolytes with suppressed Na metal loss as measured against the poor cycling performance and safety issues associated with traditional organic electrolytes and convectional current collectors. Herein, the authors report a novel strategy for fabricating an Al current collector through annealing and fluorination using hydrofluoric acid to optimize its crystal orientation and surface properties in a bid to establish highly reversible Na deposition/dissolution processes. Through a series of characterization, electrochemical, and computational analyses, it is ascertained that the F‐rich surface of the (100)‐oriented Al substrate provides high‐affinity nucleation sites that initiate and sustain a uniform Na metal deposition and form a propitious solid electrolyte interphase layer. The present anode‐free Na metal battery prototype comprised of the treated Al substrate, a high mass loading Na3V2(PO4)3 positive electrode, and an ionic liquid electrolyte achieves a high average Coulombic efficiency (≈98%) over 50 cycles: indeed, groundbreaking performance for uncoated current collectors that do not require activation cycles.

Enhanced Mechanical, Thermal, Surface, Self-Defocusing, Electro-Optic and Photoelastic Characteristics of Doped Potassium Dihydrogen Phosphate Solitary Crystals for Optoelectronic Applications

Potassium dihydrogen phosphate (KDP) is an effective NLO substance. Much research has been concentrated on KDP crystals to increase the effectiveness of KDP's nonlinear optical property. The effectiveness of laser radiation conversion can be increased by altering its expansion. The excellent molecular chirality of organic acids is employed to improve the properties of KDP. Our main objective in this study was to describe the studies on the mechanical, thermal, surface, antibacterial, self-defocusing, and electro-optic properties of doped potassium dihydrogen phosphate solitary crystals for optical, electronic, and biological applications. The effect of itaconic acid (ITA) at concentrations ranging from 1, 3, and 5 mol% on the thermal, SEM, microhardness behaviors, NLO, antibacterial properties, and half-wave voltage of KDP (potassium dihydrogen phosphate) single crystals grown by the slow cooling technique. The existence of dopants was proved with energy-dispersive spectrometry. The mechanical properties of various temperatures for undoped and doped-KDP crystals with rising dopant combinations have been prepared, and the hardness was expanded due to doping. In contrast to several potentially dangerous microorganisms like Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, the produced crystals were exposed to antibiotic activity. The superiority of the fully-fledged crystal is determined by the etching studies. Using the Z-scan method, the good third-order nonlinear response for different planes (2 0 0), (2 1 1), and (1 1 2) of the ITA-doped KDP crystal sample was determined. Half-wave voltage may be discovered in the crystal produced via electro-optic examination. The Z-scan analysis of pure and ITA-doped KDP crystals for different planes reveals good self-defocussing and NLO responses. The electro-optic experiment generated a significant and consistent half-wave voltage. The photoelastic behavior of KDP crystals with ITA as a variable birefringent compensator has been investigated.

Synthesis of porous organic framework materials based on deep eutectic solvents and their application in solid-phase extraction

This paper reviews the application of deep eutectic solvents (DESs) in the synthesis of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) as well as their prospects in the field of solid-phase extraction (SPE). Porous organic frameworks (POFs) have unique properties such as a large specific surface area, high porosity, and easy modification. Thus, these materials are widely applied in the fields of catalysis, adsorption, drug delivery, gas storage, and separation. POFs include MOFs, COFs, conjugated microporous polymers (CMPs), porous aromatic frameworks (PAFs), and covalent triazine frameworks (CTFs). MOFs are constructed from metal ions/clusters and organic ligands through coordination bonds and can be extended in two or three dimensions by repeated coordination with potential voids. COFs are formed from two monomers containing light elements (such as carbon, hydrogen, oxygen, nitrogen, boron, and other elements) via coordination bonds and have large two- or three-dimensional structures. However, conventional POF synthesis methods generally suffer from disadvantages such as long synthesis times, high temperature and pressure requirements, and the use of toxic and hazardous reaction solvents. DES consists of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD) bound by hydrogen-bonding interactions. It is a promising green solvent for material synthesis owing to its low vapor pressure, high stability, and ease of preparation. DES can be used to prepare MOFs and COFs and, in specific cases, acts as a structure-directing agent, which has an important impact on the structure and properties of the resulting frameworks. Using appropriate DES formulations, researchers can modulate the crystal structures, pore sizes, and surface properties of MOFs and COFs, resulting in materials with excellent characteristics. SPE is an analytical technique in which a sample solution is added to an SPE column; the sample solution is forced through the stationary phase, and the target compounds are collected for analysis by elution with an organic solvent. Therefore, suitable stationary-phase materials are critical for SPE. Owing to their large specific surface areas and abundant active sites, MOFs and COFs exhibit outstanding adsorption capacity and selectivity in SPE and can effectively enrich target analytes from complex samples. DES-based MOFs and COFs have shown potential use in a wide range of applications, such as in environmental analysis, food testing, and biological sample analysis. Although DES-based MOFs and COFs for SPE are still in the early stages of development, their properties such as efficient enrichment and high selectivity offer good prospects for practical applications. Future research should continue to explore DES-based synthesis methods in depth to prepare other MOFs and COFs with the desired properties and investigate their potential applications in various fields. These efforts are expected to apply these novel materials in commercialized solid-phase extraction methods, bringing new development opportunities in the field of analytical chemistry.

Laser damage properties of LiB3O5 crystal surface under UV laser irradiation.

LiB3O5 (LBO) crystal has a very high bulk laser damage threshold. Laser damage often occurs on the surfaces with a large number of processing defects during application. In this paper, the surface laser damage threshold, damage growth threshold, and damage growth curve of LBO crystal and fused silica under the same processing process have been comparatively studied by using a 355 nm pulsed laser. The surface laser damage performance of LBO crystal has been comprehensive evaluated. The results show that the laser damage threshold and damage growth threshold of LBO are about twice that of fused silica, and the damage growth coefficient is about 0.7 times that of fused silica. The detection and analysis of impurity defects and photothermal weak absorption defects show that the subsurface defects of LBO crystal are less than that of fused silica. Laser damage morphologies show that the damage process is related to strongly bonded chemical structure and anisotropic physical characteristics of LBO crystal. These characteristics together determine the high threshold damage performance of LBO crystal. The results of this study are of great guidance for the application of LBO crystal in high-power laser systems.

Effective removal of malachite green from local dyeing wastewater using zinc-tungstate based materials

The frequent use of an industrial dye such as malachite green (MG) has caused major water body deterioration and is one of the most pressing global challenges, demanding effective treatment techniques. To solve these issues, a simplistic method was developed to synthesize zinc-tungstate (ZnWO4) nanoparticles and also dope the surface matrix of the ZnWO4 nanoparticles using nonmetals of boron (B), carbon (C), and nitrogen (N) at different ratios for enhanced MG removal from wastewater. The prepared nanomaterials were characterized by different methods for crystal structure composition, surface properties, surface morphology, microstructures, functional groups, and elemental oxidation states. The BET analysis revealed a mesoporous structure with surface areas of 30.740 m2/g for ZnWO4, 38.513 m2/g for ZnWO4@BCN, 37.368 m2/g for ZnWO4@BCN/B, 39.325 m2/g for ZnWO4@BCN/C, and 45.436 m2/g for ZnWO4@BCN/N nanocomposites. The best removal of MG was accomplished at pH (8), contact period (50 min), nanoadsorbent dose (0.8 g/L), initial MG concentration (20 mg/L), and temperature (303 K). The maximum adsorption capacities of ZnWO4 and ZnWO4@BCN/N towards MG were 218.645 and 251.758 mg/g, respectively. At equilibrium, the Freundlich isotherm and pseudo-second-order kinetic models were the best fits for the experimental data of MG adsorption on both nanoadsorbents. After eight cycles of adsorption and desorption, both ZnWO4 and ZnWO4@BCN/N were found to be good at removing MG, with efficiencies of 71.00 and 74.20%, respectively. Thermodynamic investigations further validated the spontaneity and endothermic nature of the adsorption process. All study findings confirm the nanoadsorbents exceptional capability and economic feasibility for removing MG dye.

Strong metal-support interaction between AuPd nanoparticles and oxygen-rich defect ZrO2 for enhanced catalytic 5-hydroxymethylfurfural oxidation

The unique properties of metal oxide surfaces, crystal surfaces and defects play vital roles in biomass upgrading reactions. In this work, hierarchical porous bowl-shaped ZrO2 (HB-ZrO2) with mixed crystal phase was designed and employed as the support for loading AuPd bimetal with different proportions to synthesize AuPd/HB-ZrO2 catalysts. The effects of surface chemistry, oxygen defects, bimetal interaction and metal-support interaction of AuPd/HB-ZrO2 on catalytic performance for the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) were systematically investigated. The Au2Pd1/HB-ZrO2 catalyst afforded a satisfactory FDCA yield of 99.9% from HMF oxidation using O2 as the oxidant in water, accompanied with an excellent FDCA productivity at 97.6 mmol g−1 h−1. This work offers fresh insights into rationally designing efficient catalysts with oxygen-rich defects for the catalytic upgrading of biomass platform chemicals.

Exploring the acid–base surface properties of vivianite crystals in aqueous solution

The acid–base surface properties of vivianite crystals highly affect the adsorption capacity of vivianite for heavy metals and organic matters in aqueous solution. Therefore, the aim of the study was to innovatively explore and quantify the acid–base surface characterization of vivianite crystals in aqueous solution. It was found that the two surface active adsorption sites (≡POH and ≡FeOH) and five surface species thereof (i.e., ≡PO, ≡POH, ≡FeOH, ≡FeO−, and ≡FeOH2+) underwent surface reaction on vivianite crystals. Moreover, the active surface site and point of zero charge of vivianite crystals were 18 sites/nm2 and pH 5.9. Importantly, constant capacitance model was successfully employed to model the titration data, from which the distribution of surface species as function of pH and surface reaction constants were also accurately derived. The finding herein can be applied for plausible modeling molecular‐scale adsorption of the impurities on vivianite surface.