Advanced Materials Research Vols. 79-82

Abstract: CeO2 :Eu3+ powders(6mol%) were successfully prepared via the precursor,which were synthesizedby a hydrothermal method.The precursor was calcined from 500 to 800°C and CeO2:Eu3+ powders were obtained.XRD analysis showed that the powders with pure cubic fluorite-type CeO2 phase was obtained at the calcination temperatures from 500 to 800°C.TG analysis showed the precursor is no weight loss when the calcination temperature is higher than 500°C. SEM indicated CeO2:Eu3+ powders were polygonal crystal.The PL measurements indicated the dependence of PL emission intensity on the calcination temperature．The excitation spectra of the CeO2：Eu3+ powders were dominated by a broad band at 300-390 nm，suggesting the efficient energy transfer from the O2-_Ce4+ charge-transfer state to the doping Eu3+ in the CeO2:Eu3+ powders. The CeO2:Eu3+ powders with a 6at.% concentration of Eu sintered at 800°C revealed the strongest photoluminescence .

Abstract: Cu2O/TNTs(Titanium-based Nanotubes) composites were prepared by a simple “soak-deoxidize” method by using hydrazine hydrate as the reducing agent. The Cu2O/TNTs composites particles was made by changing pH and the mol ratio of Cu2+:N2H4H2O. The obtained composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis Diffuse reflectance spectra(DRS). The results of UV-Vis diffuse reflectance spectra indicate that the absorption edge of Cu2O/TNTs shows a shift to visible-light region, followed by an obvious absorption peak at 500–700 nm.

Abstract: Nano-ZrO2 particles were modified by KH-570 (γ-methacryloxypropyltrimethoxysilane). The nano-ZrO2 before and after modified were characterized by UV-VIS spectrophotometer and transmission electron microscopy (TEM). The anti-wear and friction reduction properties of nano-ZrO2 used as additive in lubrication were analyzed by friction and wear test machine of MMU-10G. The results show that the polarity of nano-ZrO2 after modified is changed, the surface free energy is reduced, and both the dispersity and stability of the modified nano-ZrO2 in organic media are improved. The modified nano-ZrO2 can increase the anti-wear and friction reduction properties of the base oil. Lubrications containing 0.10wt% and 0.05wt% nano-ZrO2 have the best tribological properties in the four-ball test and the thrust-ring test, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was used to analyze the protective layer formed on the rubbed surface, and Zr elements were found on the rubbed surface.

Abstract: The potential applications of carbon nanotubes are reviewed in this paper. With the development of modification and purification of carbon nanotubes, the scope of carbon nanotubes applications is expanded greatly. This paper pays attention to the modification and dispersion of multi-walled carbon nanotube (MWNTs). The results show that the acid treated MWNTs are highly pure and the surface of treated MWNTs is rough comparably. In addition, treated MWNTs are homogeneously dispersed without any surfactants present in organic solvents of acetone, toluene, and ethanol; the dispersive stability of carboxylic MWNTs dispersions is investigated over 2 weeks.

Abstract: The lithium absorption energies and electronic structures of boron- or silicon-doped single-walled carbon nanotubes (SWCNT) were investigated using first-principles calculations based on the density-functional theory. As B and Si doping carbon nanotubes, the lithium atom adsorption energies decrease. The effects of B and Si doping are different on the lithium atomic adsorption. B-doping forms an electron-deficient structure in SWCNT. While the Si-doping forms a highly reactive center. The calculations suggest that boron- and silicon-doping in SWCNT will improve Li absorption performance.

Abstract: A novel, low-temperature two-step synthesis method for producing BaTiO3 thin films patterned in the form of nanotubes on Ti substrates is reported. Firstly, the Ti substrate is anodized to produce a surface layer of amorphous TiO2 nanotube arrays. Secondly, the anodized substrate is subjected to hydrothermal treatment in aqueous Ba(OH)2, where the nanotube arrays serve as templates for their hydrothermal conversion to single-crystal BaTiO3 thin film. This opens the possibility of tailoring the nanotube arrays and their combinations in the hydrothermal bath, to produce ordered, patterned thin film structures of various Ti containing ceramics.

Abstract: ZnO nanorods, ZnO thick nanosheets and ZnO thin nanosheets can be facilely synthesized at low temperature using Zn(CH3COO)2•2H2O, Zn(NO3)2•6H2O and ZnSO4•7H2O as zinc resources, respectively. In the novel synthesis process, the precursors were firstly prepared using the reaction of zincate and NaOH in ethanol/water mixed medium. Then ZnO nanorods and ZnO nanosheets can be obtained by calcined procuesors at 300°C. The method is simple and low cost and expected to be applied in industry in the future. In addition, the mixed medium could be recycled by distillation process. The kinds of zinc resources and reaction temperature have a noticeable effect on the morphology of the ZnO particles produced.

Abstract: The 16Cr-1C martensitic stainless steel can provide the higher hardness and better wear resistance for 440C steel. The microstructure of DLC coatings were observed by optical microscope and field-emission scanning electron microscope (FE-SEM). The compositional depth profile of DLC films were measured by field-emission Auger electron spectroscopy (Fe-AES). In addition, the micro-hardness and elastic modulus of DLC films were measured by nano-indentation tests. Experimental results show that the total thickness of coating was in the range of 600nm~1100nm. This coating was included of Ti/TiC transition layer and DLC layer. The Ti/TiC transition layer was grown on the 440C stainless steel substrate, and the upper layer was DLC layer. This layer structure was confirmed by the FE-AES analysis. The micro-hardness of DLC coating was measured in the range of 24.2GPa~26.0GPa, and the elastic modulus was measured in the range of 264GPa~313GPa in the nanoindentation test. The nanoscratch results show that DLC films have lower friction coefficients than 440C substrate.

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Abstract: Fe-Co-N thin films with various Co content were synthesized on Si (111) substrate using facing-target magnetron sputtering by changing sputtering input power on Co target. During deposition, the input power on Fe target was kept at 160 W. The composition, structure, and magnetic properties were examined by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device. XRD and TEM investigations showed that at lower input power of 11.2 W on Co target, the phases in the film were -(Fe,Co)4N and Co3N. Increasing sputtering input power, the content of Co in the film increased. At input power of 14 W, film contained -(Fe,Co)8N phase was produced which exhibited higher saturation magnetization (252.85 Am2/kg) and lower value of coercivity (3.66 kAm-1), corresponded to the 12% content of Co in the film.