Ferric Phosphate Hydroxide Microstructures Affect Their Magnetic Properties

Uniformly sized and shape-controlled nanoparticles are important due to their applications in catalysis, electrochemistry, ion exchange, molecular adsorption, and electronics. Several ferric phosphate hydroxide (Fe₄(OH)₃(PO₄)₃) microstructures were successfully prepared under hydrothermal conditions. Using controlled variations in the reaction conditions, such as reaction time, temperature, and amount of hexadecyltrimethylammonium bromide (CTAB), the crystals can be grown as almost perfect hyperbranched microcrystals at 180 °C (without CTAB) or relatively monodisperse particles at 220 °C (with CTAB). The large hyperbranched structure of Fe₄(OH)₃(PO₄)₃ with a size of ∼19 μm forms with the “fractal growth rule” and shows many branches. More importantly, the magnetic properties of these materials are directly correlated to their size and micro/nanostructure morphology. Interestingly, the blocking temperature (T_B) shows a dependence on size and shape, and a smaller size resulted in a lower T_B. These crystals are good examples that prove that physical and chemical properties of nano/microstructured materials are related to their structures, and the precise control of the morphology of such functional materials could allow for the control of their performance.     

A New Fluorescence Turn-On Probe for Aluminum(III) with High Selectivity and Sensitivity,and its Application to Bioimaging

The development of novel selective probes with high sensitivity for the detection of Al³⁺ is widely considered an important research goal due to the importance of such probes in medicine, living systems and the environment. Here, we describe a new fluorescent probe, N′-(4-diethylamino-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (1), for Al³⁺. Probe 1 was evaluated in a solution of acetonitrile/water (1:1 v/v). Compared with previously reported probes for Al³⁺, probe 1 can be synthesized easily and in high yield. A Job plot confirmed that probe 1 is able to complex Al³⁺ in a 1:1 ratio, and the binding constant was determined to be 4.25×10⁸ m⁻¹. Moreover, the detection limit was as low as 6.7×10⁻⁹ m, suggesting that probe 1 has a high sensitivity. Common coexistent metal ions, such as K⁺, Co²⁺, Ca²⁺, Ba²⁺, Ni²⁺, Pb²⁺, Hg²⁺, Ce²⁺, Zn²⁺, Cd²⁺, Fe³⁺, showed little or no interference in the detection of Al³⁺ in solution, demonstrating the high selectivity of the probe. Finally, the ability of probe 1 to act as a fluorescent probe for Al³⁺ in living systems was evaluated in Gram-negative bacteria, Escherichia coli, and confocal laser scanning microscopy confirmed its utility. The results of this study suggest that 1 has appropriate properties to be developed for application as a fluorescent probe of Al³⁺ for use in biological studies.     

Yttrium Complexes of Arsine,Arsenide, and Arsinidene Ligands

Deprotonation of the yttrium–arsine complex [Cp′₃Y{As(H)₂Mes}] ( 1 ) (Cp′=η⁵‐C₅H₄Me, Mes=mesityl) by nBuLi produces the μ‐arsenide complex [{Cp′₂Y[μ‐As(H)Mes]}₃] ( 2 ). Deprotonation of the As H bonds in 2 by nBuLi produces [Li(thf)₄]₂[{Cp′₂Y(μ₃‐AsMes)}₃Li], [Li(thf)₄]₂[ 3 ], in which the dianion 3 contains the first example of an arsinidene ligand in rare‐earth metal chemistry. The molecular structures of the arsine, arsenide, and arsinidene complexes are described, and the yttrium–arsenic bonding is analyzed by density functional theory.     

Synergistic effect of aluminum hypophosphite and intumescent flame retardants in polylactide

Aluminum hypophosphite (AHP) was introduced into polylactide/intumescent flame retardant (PLA/IFR) systems by melt blending. The flame retardant and thermal properties of the PLA composites were investigated. The results suggest that a synergistic effect exists between IFR and AHP on the char formation and anti‐dripping behavior of PLA composites. The PLA/IFR composites containing 10 wt% IFR can pass the UL‐94 V‐0 rating but the test is accompanied by heavy melt dripping. For the PLA/AHP a UL‐94 V‐2 rating is obtained for the same loading of IFR. However, the composites containing 7 wt% IFR and 3 wt% AHP pass the UL‐94 V‐0 rating with modified dripping behavior. Moreover, the char from combustion of PLA/IFR is flexible but of poor quality. That for PLA/AHP is brittle with many cracks. In contrast, that for PLA/IFR/AHP is strong and compact. Thus it can resist the erosion due to heat and gas formation and protect the inside of the matrix. In addition, AHP causes the crosslinking among APP, which promotes the char formation and prevents the melt dripping. This is the main reason for the good flame retardant properties of PLA composites. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorine plasma treatment of bare and nitrilotris(methylene)triphosphonic acid (NP) protected aluminum: an XPS and ToF‐SIMS study

Nitrilotris(methylene)triphosphonic acid (NP) is a technologically important molecule that has been used for years as a corrosion inhibitor and/or adhesion promoter on aluminum and other metal surfaces. However, to the best of our knowledge, the detailed surface characterization of NP adsorbed on aluminum, or on any other surface, has not been reported. Herein, we report an X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) analysis of a series of untreated and NP‐coated aluminum substrates that were exposed to the downstream products of a fluoroalkane + oxygen plasma for different amounts of time (from 0 to 20 s). As indicated by P 2p, N 1s, Al 2p, O 1s, and F 1s narrow scans, even a 4‐s plasma treatment significantly damages the NP protective layer and converts the native aluminum oxide into aluminum oxyfluoride. Heat treatment of the fluorine plasma‐treated samples in the air substantially converts the aluminum oxyfluoride back to aluminum oxide, while similar heating under vacuum results in little change to the materials. A slow loss of fluorine from the samples occurs over the course of weeks when they are stored in the air. A ToF‐SIMS analysis reveals sets of signals that are consistent with no surface treatment, NP treatment, or fluorine plasma treatment. A principal component analysis of the negative ion ToF‐SIMS spectra from the samples shows the expected differentiation of the samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Y2O3 on microstructural characteristics and wear resistance of cobalt‐based composite coatings produced on TA15 titanium alloy surface by laser cladding

The effects of Y₂O₃ on the microstructure, phase composition of the coatings, microhardness and wear resistance of cobalt‐based composite coatings prepared by laser cladding were investigated. The TA15 titanium alloy was selected as substrate which the cobalt‐based composite powder with different content of Y₂O₃ was cladded on. The microstructure of the coatings was observed by scanning electron microscope (SEM) and metallurgical microscope. The phase structure of the coatings was determined by X‐ray diffraction (XRD), and the microhardness and wear resistance of the coatings were measured by hardness tester and wear testing machine. The results show that the rare earth oxide Y₂O₃ can refine and purify the microstructure of the coatings, reduce the porosities and cracks and improve compactness of the coatings. Moreover the addition of Y₂O₃ improves the microhardness of the coatings and reduces the friction coefficient, thus improving the wear property of the coatings. And the wear resistance of the coating with Y₂O₃ has improved about 50 times; the highest value of microhardness in the coating is HV1181.1. And 0.8 wt% content of Y₂O₃ in the coating is the best choice for improving the microhardness and wear resistance of the coating. It is feasible to improve the microstructure and tribological properties of laser cladding coatings by adding of Y₂O₃. Copyright © 2014 John Wiley & Sons, Ltd.     

The first montmorillonite‐supported surface single‐structure titanium complex: synthesis,characterization and catalytic activity in alkene epoxidation

A well‐defined single‐site titanium‐modified montmorillonite (MMT) with only one geometric construction ((?SiO)₃–Ti–NMe₂) was obtained in moderate conditions. Reaction of tetrakis(dimethylamido)titanium with hydroxylated MMT was conducted by surface organometallic chemistry technique, and the surface structure was characterized by in situ Fourier transform infrared spectroscopy, ¹³C cross polarization magic angle spinning nuclear magnetic resonance, X‐ray photoelectron spectroscopy, extended X‐ray absorption fine structure, and elemental analysis. The catalytic activity in alkene epoxidation was evaluated, and the results revealed that the steric hindrance of the substances is responsible for the catalytic activity of the MMT‐supported titanium complex but to the characteristic restricted layer‐like structure of the MMT. Copyright © 2014 John Wiley & Sons, Ltd.     

Single‐phase TiO2 formation by plasma oxidation of titanium thin films

Synthesis of titanium oxide film by plasma oxidization of the metallic films is investigated. Argon/oxygen gas mixture in the pressure range 30 × 10^?2 mbar is used for plasma processing at a frequency of 250 kHz. The plasma‐oxidized films are annealed in a tube furnace in argon atmosphere to establish crystalline‐phase formation. X‐ray diffraction and Raman spectroscopic results manifest peaks corresponding to rutile TiO₂. Ultraviolet‐Visible (UV‐Vis) spectroscopic analysis confirms the bandgap of rutile TiO₂, and photoluminescence spectra exhibit peaks due to oxygen defects. Homogeneity across the film's thickness and the nature of the film substrate interface is studied by depth profiling acquired using secondary ion mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd.     

锂离子电容器(LIC)产业前沿技术研究进展

新能源战略体系的建设和电子技术的飞速发展对储能器件的性能提出了更高的要求,锂离子电容器是将锂离子电池和双电层电容器“内部交叉”的新型混合储能器件,兼具高能量密度和高功率密度,近年来引起了国内外的广泛关注.本文阐述了锂离子电容器的工作原理和国内外产业发展现状,总结了碳负极的预赋锂技术、电极材料与体系匹配性研究等关键技术前沿的研究成果,并提出了后续产业化研究中所需要解决的实际问题.