Materials Science Forum Vols. 809-810

Abstract: A kind of convenience route to prepare In₂S₃ nanorods was introduced. In the pyridine solvothermal system, In (acac)₃ was used as the indium source, lauryl mercaptan as the sulfur source. The formation mechanism of the nanorods was proposed and photoluminescence property was also detected.

Abstract: Chromium nitride (CrN) nanopowders were successfully synthesized in high pressure gas-solid reaction bed with chromium hydroxide as a precursor. A special liquid-phase precipitation method was used to prepare the powders of chromium hydroxide.The aminolysis of chromium hydroxide was carried out for 2-4 hours at temperatures from 650°C to 850°C and at pressures up to 0.8MPa. The effect of the reaction pressure on the grain size and crystalline morphology of CrN powders were characterized by transmission electron microscopy and X-ray diffraction. The results indicate that high purity CrN powders with grain size of 40-60 nm can be obtained through the aminolysis at temperature of 650°C and pressure of 0.6MPa for 2 hours.

Abstract: Stable and uniformly dispersive silver nanoparticles were prepared though reducing silver nitrate with polyvinylpyrrolidone. The effects of preparing conditions on the stability of silver nanoparticles were investigated. The results showed that the surface plasmon resonance (SPR) band of the silver nanoparticles was about 403nm. The silver nanoparticles remained stable for more than one month. Water, alkali solution and glucose could accelerate the reaction. The stability of the silver nanoparticles was increased by adding glucose.

Abstract: There are many kinds of preparation methods of silver nanoparticles ,such as chemical method, physical method plant reduction method and microbial enzyme and so on. The most common method is to use chemical method for reduction. But this method needs to add some chemicals that will produce environmental pollutants. The production consumption will be increased. High quality nanometer silver needing low cost and according with environment protection needs was prepared by using homogeneous precipitation that contains no auxiliary reagent and high temperature pyrolysis in this paper. Experimental results that this method is very effective.

Abstract: Soft magnetic alloys Fe₉₅Nd₅ and Fe_89.5Nd_10.5 were made by the mechanically ball milling to investigate the influence of Nd doping on the magnetic properties of Nd₂Fe₁₄B/α-Fe nanocomposite magnets. The coercivity was enhanced with increasing Nd of the pre-alloyed Nd-Fe soft powders. The further discussions on Nd₂Fe₁₄B/α-Fe nanocomposite were also carried out through directly mixing the pure Nd as the interface improving agent. Compared with Nd-Fe pre-alloys, the direct addition of Nd was more favorable to reinforce the coercivity of nanocomposite magnets and the squareness of demagnetization curve, thereby increasing the maximum magnetic energy product.

Abstract: Large-area SiNWs has been successfully fabricated through one-step metal-assisted chemical etching process at room temperature. The effects of key fabrication parameters (AgNO₃ concentration, Fe (NO₃)₃ concentration, and etching time) on the nanostructure SiNWs were carefully investigated by SEM, TEM, respectively. The results show that AgNO₃ concentration and Fe (NO₃)₃ concentration play important roles to the lengths and arrangements of SiNWs arrays in one-step MACE. The morphological transition of Si surfaces from solid nanowires to porous nanowires can be found with increasing AgNO₃ concentration and Fe (NO₃)₃ concentration, which indicates that the re-dissolved Ag⁺ would work as the main oxidative species for oxidizing the silicon substrate and forming SiNWs in the HF/ AgNO₃/ Fe (NO₃)₃ etching system. The length of SiNWs is increased with increasing AgNO₃ concentration from 0.005 mol/L to 0.02 mol/L and etching time, the chemical polish phoenomenon can be observed when the Fe (NO₃)₃ concentration increases to 0.5 mol/L. A novel mechanism is proposed to explain the formation of SiNWs in HF/ AgNO₃/ Fe (NO₃)₃ solution.

Abstract: In the present work, the giant magnetoimpedance effect has been found in Fe_73.5Cu₁Nb₂V₁Si_13.5B₉ nanocrystalline ribbons. The optimum annealing temperature for obtaining largest GMI is about 550°C. Fe_73.5Cu₁Nb₂V₁Si_13.5B₉ with average grain size of 15 nm after annealing at 550°C for 30 min presents a magnetoimpedance of-74% at 700 kHz under H=90 Oe. The MI effect at high frequency is due to the change of Z via the variation of permeability or the penetration depth under the external field. The positive magnetoimpedance ΔZ/Z is 36% and positive magnetoresistance ΔR/R is 79% at H= 10 Oe and f=5MHz. We observe a huge magnetoreactance ΔX/X of –375% at a very low frequency of 50 kHz, which is a magnetoinduction effect due to the movement of domain wall. The smaller GMI for nanocrystalline Fe_73.5Cu₁Nb₂V₁Si_13.5B₉ ribbons annealed above 550°C is mainly connected with the decrease of permeability due to the precipitation of Fe₂B phase in ribbons. Our results show that the partial substitution of expensive Nb by cheap V in FeCuNbSiB could be a successful way to prepare the GMI materials with high performance and low cost.

Abstract: The films of polypropylene/ modified carbon fibers (PP/MCF) were made by physical blending method under refluxing and stirring for 3h at 130 °C. The structure of chemical bond in PP/MCF was investigated by fourier transform infrared spectroscopy (FT-IR), and optical properties were characterized by UV-Vis reflective spectroscopy, UV-Vis transmission spectroscopy and Polarizing microscope. We focus on the effects of MCF content on the material hardness properties according by GB/T6739-2006/ ISO 15184: 1998, and the mass loss, crystallization and melting behavior of the samples were test by TG and DSC. The results show that increasing MCF content is conducive to reduction in the hardness and improve the smoothness, and to reduction the crystallization peak temperature and improve the melting point. So we can adjust MCF content to prepare the films used for the gasket within prosthetic socket.

Abstract: TbFeO₃ nanoparticles were synthesized using Tb₄O₇ and Fe (NO₃)₃·9H₂O as the main raw material by a one-step microwave process. The prepared nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). XRD and SEM demonstrate the successful synthesis of single phase TbFeO₃ and an average grain size of 40-100 nm in diameter. The single phase structure of TbFeO₃ was yet maintained after calcination at 800 °C. The photocatalytic experiment shows the high visible-light photocatalytic activity for the decomposition of methyl orange.

Abstract: Crown ether 18C6 was used as a phase transfer catalyst (PTC) for the interfacial polymerization of polypyrrole (PPy). Usually, in interfacial reacting system, oxidant FeCl₃ was dissolved in deionized water to form aqueous phase, while pyrrole was dissolved in chloroform to form organic phase. The 18C6 PTC can efficiently form complexes with Fe (III) and transfer Fe (III) from aqueous phase into organic phase, resulting in nanoscale hollow-bubbly PPy with better electronic properties. UV-vis was used to confirm the phase transfer ability of composed Fe (III). Cyclic Voltammograms (CVs) were used to characterize capacitance property of PPy. Fourier Transition Infrared (FT-IR) spectroscopy and Scanning Electronic Microscopy (SEM) were carried out to investigate the microstructure of PPy. Finally, defect control migration growth mechanism of PPy during the polymerization has been carefully discussed.