T型微混合器合成Cu2O纳米颗粒

采用T型微混合器通过沉淀法,以氯化铜为铜源,氢氧化钠为沉淀剂,抗坏血酸为还原剂制备出了立方体氧化亚铜纳米颗粒。考察了进料流量、氢氧化钠浓度、抗坏血酸浓度和温度对产物氧化亚铜的形貌、粒度及其分布的影响。采用X射线衍射、场发射扫描电子显微镜和紫外可见分光光度计对其进行表征。结果表明,随着进料流量的增大、氢氧化钠浓度的减小、抗坏血酸浓度的增加和温度的提高,所制备的氧化亚铜颗粒的平均粒径减小、粒度分布变窄。     

Amidohydroxylated polyester with biophotoactivity along with retarding alkali hydrolysis through in situ synthesis of Cu/Cu2O nanoparticles using diethanolamine

In this research, polyester fabric was modified through in situ synthesis of Cu/Cu₂O nanoparticles (NPs) in one single step processing using diethanolamine. This introduced amide and hydroxyl active groups on the polyester surface, adjusted pH, aminolyzed, and improved the surface activity of polyester. Copper sulfate was used as precursor, sodium hypophosphite as a reducing agent and polyvinylpyrrolidone as a stabilizer in a chemical reduction route at boil as a facile and cost‐effective approach. The central composite design was also utilized to optimize the processing conditions and study the effect of each variables on the weight gain, color change, and wettability of the treated fabrics. FESEM and mapping, EDX, XRD, and FTIR analysis confirmed effective assembling of Cu/Cu₂O NPs on the amidohydroxylated polyester surface. The optimum treated fabric showed excellent antibacterial properties on both Staphylococcus aureus and Escherichia coli. In addition, a very good photocatalytic activity towards degradation of methylene blue solution obtained after 24 h sunlight irradiation. Further, the hydrophilicity, mechanical properties and stability of the treated fabrics in concentrated sodium hydroxide improved through formation of amidohydroxyl active groups, amidoester cross‐linking and nanocross‐linking within polymeric chains through in situ synthesis of Cu/Cu₂O. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44856.     

A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.     

Corrections to the phase diagram of the Mg-O-Al2O3-SiO2 system

Translated from Steklo i Keramika, No. 10, pp. 11–12, October, 1992.     

Joining of Al2O3 ceramic to Cu using refractory metal foil

Joining of Al₂O₃ ceramic to Cu has been conducted with Ag-26.7Cu-4.5Ti braze and refractory metal (W or Ta) foil. The interfacial microstructure in the joint with W foil is similar to that with Ta foil. The joining region in the joint consists of a reaction zone, braze zone I, refractory metal layer and braze zone II. The reaction zone of Cu₃Ti₃O with a thickness of about 5 μm develops close to Al₂O₃ side due to the reactions of Ti and Cu in the braze with Al₂O₃ substrate. The braze zones I and II are mainly composed of Ag- and Cu-based solid solutions. For the joint with W foil, the adsorption of Ti at the braze/W interfaces followed by the Ti diffusion into W foil occurs, whilst slight dissolution and diffusion of Ta into the brazes take place in the joint with Ta foil. The average shear strengths of joints with W and Ta foils are much higher than those without refractory metal foil, indicating the contribution of the refractory metal foil to the improvement of joint mechanical strength. Introduction of refractory metal foil in Al₂O₃/Cu joining is beneficial for the shift of joint residual stress distribution and the decrease of stress concentration in the joint since the coefficient of thermal expansion (CTE) of refractory metal layer approximately approaches that of Al₂O₃. Furthermore, a slight thickness increase of the Cu₃Ti₃O reaction zone in the joint with refractory metal foil may also give rise to the joint strength promotion.     

Phase diagram study and thermodynamic modeling of the MgO-Y2O3-MgF2-YF3 system

The phase diagram of the MgO-Y₂O₃-MgF₂-YF₃ system (Mg,Y//O,F reciprocal system) at 1273–1773 K was investigated for the very first time using a classical equilibrium/quenching and differential thermal analysis (DTA) experiments followed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) phase analyses. No ternary or quaternary crystalline phase was found, and the eutectic reactions in the reciprocal system were identified. The overall phase diagram of the reciprocal system was also calculated based on the thermodynamic modeling using the CALculation of PHAse Diagram (CALPHAD) method.     

Phase diagram study and thermodynamic assessment of the Y2O3-YF3 system

The phase diagram of the Y₂O₃-YF₃ system up to 1973 K was investigated using a classical equilibration/quenching experiment and differential thermal analysis (DTA). Equilibrium phases were confirmed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) phase analysis. For the very first time, the entire range of the phase diagram of yttrium oxy-fluoride system up to 1973 K was experimentally determined. Cubic-Y₂O₃ phase dissolves more than 5 mol% of YF₃ at 1973 K. The melting points of YOF and vernier phases are found to be higher than 1973 K and their steep liquidus in the YF₃-rich region are determined. Based on new experimental phase diagram data and thermodynamic property data in the literature, the Y₂O₃-YF₃ system was thermodynamically modeled by the CALculation of PHAse Diagram (CALPHAD) method. As applications of the thermodynamic database, metastable solubilities of YF₃ in Y₂O₃ during plasma etching process were calculated.     

A note on the theory of heterogeneous nucleation and growth of condensed phases

Initial phase of heterogeneous nucleation of metal electrochemically deposited under conditions of constant overpotential, has been studied by computer simulation using modified version of the kinetic approach to nucleation. Conditions causing “instantaneous” and “progressive” nucleation have been found. It could be shown that both types can occur at any overpotential, the determining factor being the value of the rate-constant of attachment of atoms to clusters, relative to the value of the anodic component of the current. Specific characteristics of the electrochemical system come into play only as much as they determine the attachment constant.     

Experimental study of nucleation and quality of CVD diamond adopting two-step deposition approach using MPECVD

Effects of the deposition conditions on quality and nucleation density of CVD diamond were investigated using a microwave plasma enhanced chemical vapor deposition (MPECVD) method with methane-hydrogen gas mixtures. Diamond films were deposited at pressures of 665–4000 Pa, temperatures of 660–950 °C, and methane concentrations of 0.5–5 vol.%. Deposited diamond films were characterized by scanning electron microscopy, field emission scanning electron microscopy, micro-Raman spectroscopy, and X-ray diffraction. Diamond quality and nucleation density significantly affected by the deposition pressure, substrate temperature, and methane concentration. The findings of this work were discussed in terms of the effects of deposition conditions on the plasma composition. A two-step deposition approach was applied to improve nucleation density and quality of CVD diamond films. Polycrystalline diamond films were grown using the two-step deposition process changing a combination of parameters in the two steps. Growth and quality of the deposited diamond films were improved altering the deposition pressure and substrate temperature in the two steps.     

YBa2Cu3O7‐δ superconductor bulks composited by Y2BaCuO5 nanoparticles derived from homogeneous nucleation catastrophe

The refinement of Y₂BaCuO₅ (Y211) particles is a matter of significant importance in fabricating high‐performance YBa₂Cu₃O_7‐δ (Y123) superconductor bulks by top‐seeded melt growth (TSMG). However, coarsening and epitaxial growth naturally occur to the preexisting Y211 grains in the conventional process, causing an unwanted size enlargement. Here, for the first time, we report a novel TSMG approach in which instead of Y211, modified precursor powders (MPP, Y₂O₃, and Ba₂Cu₃O_x) were employed. As a result, massive numbers of Y211 nanoparticles were derived from the homogeneous nucleation catastrophe through peritectic solidification of Y₂O₃+Ba_x‐Cu_y‐O→Y211. Correspondingly, superior property of trapped field was achieved from the MPP‐processed bulk.     

Phase diagram of the system Al2O3-SiO2

Phase diagrams of the system Al₂O₃ - SiO₂ as presented in the domestic and foreign literature are analyzed. The congruent and incongruent states of mullite, liquation in the solid phase, and the structures of mullite and sillimanite are discussed.Translated from Ogneupory, No. 8, pp. 11 – 14, August, 1995.A lecture delivered to metallurgists and silicate producers at the Ural State Engineering University.     

Cu/Cu2O nanoparticles modified Ti3C2 MXene with in-situ formed TiO2-X for detection of hydrogen peroxide

Hydrogen peroxide (H₂O₂) is frequently used in various chemical reactions, the food industry, environmental protection, and the medical and biological fields. Cost-effective, simple, and quick detection technologies with great sensitivity are highly desired. The emerging two-dimensional MXene is favorable in the sensing field due to its outstanding conductivity, stability, and large surface area. Moreover, the in-situ generated TiO_2-X on Ti₃C₂ MXene has been proven an excellent biosensor material due to its biocompatibility. Herein, we decorated Cu/Cu₂O nanoparticles onto Ti₃C₂ MXene with in-situ generated TiO_2-X nanoparticles, forming heterojunction through a simple one-step hydrothermal process. The Cu/Cu₂O/TiO_2-X/Ti₃C₂ (Cu/Cu₂O/TT) exhibits good electrochemical sensing capability toward H₂O₂, with a linear range up to 28.328 mM, a sensitivity of 312 μA mM^?1 cm^?2, and a detection limit (LOD) of 0.42 μΜ. The synergistic interactions between Cu/Cu₂O nanoparticles and TiO_2-X/Ti₃C₂ heterojunction not only improved electron transfer and electrocatalytic activity, but also facilitated the mobility of targeting molecules on the catalyst due to the abundance of exposed catalytic sites. Therefore, compared to TiO_2-X/Ti₃C₂, Cu/Cu₂O/TT has a lower LOD, faster reaction, and five times the sensitivity. Additionally, the outstanding photoelectrochemical (PEC) sensing performance is demonstrated of Cu/Cu₂O/TT for H₂O₂ detection, displaying a low LOD, long-term stability, repeatability, and selectivity. This report may expand the application of MXene-based materials as electrochemical sensors.     

Phase diagram of the Al2O3–ZrO2–La2O3 system

The phase diagram of the Al₂O₃–ZrO₂–La₂O₃ system was constructed in the temperature range 1250–2800 °C. The liquidus surface of the phase diagram reflects the preferentially eutectic interaction in the system. Three new ternary and two new binary eutectics were found. The minimum melting temperature is 1665 °C and it corresponds to the ternary eutectic LaAlO₃ + T-ZrO₂ +  La₂O₃·11Al₂O₃. The solidus surface projection and the schematic of the alloy crystallization path confirm the preferentially congruent character of phase interaction in the ternary system. The polythermal sections present the complete phase diagram of the Al₂O₃–ZrO₂–La₂O₃ system. No ternary compounds or regions of remarkable solid solution were found in the components or binaries in this ternary system. The latter fact is the theoretical basis for creating new composite ceramics with favorable properties in the Al₂O₃–ZrO₂–La₂O₃ system.     

Kinetics of nucleation and growth of metal nanoparticles in heterogeneous media in the presence of surfactants

The computer simulation of the processes of the nucleation and growth of nanoparticles in heterogeneous media (for example, in polymer solution or porous polymer matrix) in the presence of surfactant has been carried out. Heterogeneous medium has been modeled by a system of pores that limit the region of the nanoparticle formation. It is assumed that surfactant molecules, which were present in the system initially, adsorb on the surface of the nanoparticles and slow down their growth in the oversaturated solution. The complete blocking of the nanoparticles occurs when their surface is covered by the surfactant molecules to a certain degree and their growth stops. It is shown that the degree of heterogeneity and the value of surfactant concentration significantly affect both the mean size of the nanoparticles and the character of their size distribution.     

The formation and growth of Fe2O3 nanoparticles from the photo-oxidation of iron pentacarbonyl

Particle size distributions from a series of experiments involving the photo-oxidation of iron pentacarbonyl [Fe(CO)₅] in ozone at atmospheric pressure and 295 K are reported for a range of initial reactant concentrations, varying photolysis rates and particle growth times. These data sets were used to test a model which describes the formation of FeO₃ in the gas phase, followed by clustering to produce primary Fe₂O₃ particles. These subsequently coagulate to form fractal-like structures as a result of magnetic dipole coupling of the primary particles.For the smallest size, spherical particles, Smoluchowski theory was used to determine a coagulation constant (k_S) of 7.0×10^?10 cm³ s^?1, indicating a primary particle diameter of 6.6 nm, in very good agreement with the optimised value used in the particle growth model for this system.Finally, these findings are used in discussion of the formation and growth of Fe₂O₃ ‘meteoric smoke’ particles in the upper atmosphere.     

Direct graphene growth on (111) Cu2O templates with atomic Cu surface layer

This work explores nucleation and epitaxy of graphene on crystalline Cu₂O templates formed via self-assembly and surface reduction of Cu₂O nanocrystallites on the cubic textured (100) orientation Cu (CTO-Cu) and polycrystalline Cu (poly-Cu) substrates, respectively. It has been found that the presence of sub-surface oxygen causes the reconstruction of Cu surface due to the formation of oriented Cu₂O nanocrystallites at a low H₂ gas flow. Self-assembly of the Cu₂O nanocrystallites into a textured surface template provides direct nucleation sites for graphene growth after the oxygen-sublattice on the template surface is reduced. The atomic Cu surface layer provides advantages of high graphene growth rate due to the catalytic role of Cu and in-plane alignment of graphene nuclei. It is particularly important that the Cu₂O crystallites have predominantly (111) orientation aligned to each other in the plane of the (100) CTO-Cu substrates, which allows epitaxy of graphene with much lower defect density as compared to that in the poly-Cu case. Since Cu₂O (111) templates may be developed on lattice matched (100) surfaces of other dielectric materials, this self-assembly approach provides a promising pathway for large-scale, transfer free graphene epitaxy on nonmetallic surfaces.     

Membrane enhanced COD degradation of pulp wastewater using Cu2O/H2O2 heterogeneous Fenton process

Both activity and stability of the catalyst can be improved in heterogeneous Fenton reaction, in particular, with no limitation for the working pH and no production of the sludge. In this work, a combination of catalyst Cu₂O and pore-channel-dispersed H₂O₂ is proposed to treat the pulp wastewater. Degradation degree of CODs in the wastewater was up to 77% in the ceramic membrane reactor using Cu₂O powder (2.0 g·L^-1) and membranefeeding H₂O₂ (0.8 ml·L^-1) within 60 min. Evolution of ·OH radical formation in the advanced oxidation process was analyzed with a fluorescent method. Utilization efficiency of H₂O₂ was successfully enhanced by 10% with the membrane distributor. Further on, the catalyst recyclability was evaluated in a five-cycle test. The concentration of copper ions being dissolved in the treated water was monitored with ICP. After Cu₂O/H₂O₂ (membrane) treatment the effluent is qualified to discharge with COD concentration lower than 15 mg·L^-1 with regard to the national standard GB25467-2010.