Applied Mechanics and Materials Vol. 618

Abstract: Al₂O₃(x)/ZrO₂ composite ceramics were successfully prepared by microwave sintering. The influence of variety content of nanoAl₂O₃ on mechanical properties and microstructure of ZrO₂ dental materials were studied, and analysied the mutual relations of chemical composition, mechanical properties and microstructure to investigate the reason of strengthening and toughening. Results indicated that The relative density of the Al₂O₃(x)/ZrO₂ composite ceramics reached more than 96.8%.The HV hardness ,bending strength and fracture toughness presented excellent mechanical properties as 12.5GPa, 753.8MPa and 11.8MPa·m^1/2 with the content of nanoAl₂O₃ was 7.5%. Compared with that of pure ZrO₂ ceramics, the bending strength and the fracture toughness were improved 19% and 96%, respectively. The main crystal phases in this composite ceramics were t-ZrO₂ and α-Al₂O₃.The nanoAl₂O₃ have a obvious effect on the strength and toughness of ZrO₂ based ceramics. The reason of strengthening and toughening mainly the additions reduced the ZrO₂ grains growth and promoted grains size uniformity, and changed the fracture mode from transgranular fracture to intergranular fracture characteristics.

Abstract: In recent years, single particle detection techniques based on driving nanoparticles through nanoscopic pores with a voltage or pressure had been the subject of numerous studies. Since particles with high charge, such as DNA and proteins, have been widely used for research, there was little information about the translocation behavior of nanosized particles which with low charge. However, nanoparticles include virus and colloids are important samples for nanopore sensing technology. In this study, we employed the solid-state nanopore to sense nanoparticles as fundamental study. Nanopore with diameter of 185 nm has been used to detect the nanoparticles with compared low zeta potential of-16 mv in different voltages. And simulations of electric field strength was made by using COMSOL Multiphysics to assist analyze the translocation behavior. The result suggests that the nanoparticles could transport the nanopore under the large electric field. By rising up the bias voltage could favor the detection of the nanoparticles.

Abstract: In this paper, highly ordered TiO₂ nanotubes were performed by the method of anodic oxidation, using glycerol / water, NH₄F as the electrolyte, and Oxidation voltage to 25v for 1h. TiO₂ nanotube surface modified by Ag nanoparticles, by using UV light to restore Ag⁺ to Ag, the Ag⁺ from AgNO₃ solution sputted out by ultrasonic. Ag-doped TiO₂ was used to degrade acetic acid concentrations under UV light. Different Ag/TiO₂, HAc concentration, and light intensity were selected as effect factors, TiO₂ as contrast test.

Abstract: A series of experiments have been carried out to study on the efficiencies in solar energy materials and solar cells. Dye-sensitized solar cells (DSSCs) are good examples of where the quality of the nanomaterials and their interfacial properties are important to device performance. In this report, Nanometer TiO₂ sol for coating film was prepared by cooperating hydrothermal colloidal sol with organic polymer dispersing agent (PVA). Nanocrystalline TiO₂ porous films were prepared by using electro-hydrodynamic technique (EHD). The results show the films prepared by EHD technique have multilevel hierarchical structure, therefore, better optical scattering properties. Different constituent quasi-solid electrolytes with blood mimetic thixotropy were prepared by cooperating ionic liquid electrolyte with nanometer TiO₂ colloidal sol synthetized by sol-gel method. The resulting Quasi-Solid-State dye-sensitized solar cells consist of nanoporous TiO₂ Film and the dye N3, show conversion efficiencies up to 3.7 percent (8. 51 percent with a mask).

Abstract: The preparation of magnetite nanoparticles with controlled size has attracted of scientific and technological broad attention. Spherical magnetite nanoparticles in the size range from 8nm to 22 nm were synthesized by coprecipiation method using hexadecyl trimethyl ammonium bromide (CTAB) as dispersant. Magnetite nanoparticles have good dispersibility and uniform particles size distribution. The properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), automated surface area and pore size analyzer, vibrating sample magnetometer (VSM) and the catalytic performance was measured using high performance liquid chromatography (HPLC). The saturation magnetization is 13.785emu/g, and the coercive force of the sample is 23.738G, the average size of the particles is 13.6 nm, specific surface area is 19.318 m²/g and phenol conversion is up to 99.5%. These results indicate the synthesized magnetite particles have good performance.

Abstract: Substoichiometric germanium oxide nanoparticles were synthesized through gas aggregation process with a careful control on the size, composition and crystallinity of the nanoparticles. The nanoparticles show broad room temperature photoluminescence (PL) in the 470nm to 600nm wavelength region. The microstructure and optical properties of the nanoparticles were investigated. We found that the photoluminescence behavior of the nanoparticles is critically influenced by their compositions. Through temperature-dependent photoluminescence and time-resolved photoluminescence spectroscopy, we concluded that the broad PL band originated from the defects in the GeOx shell layers, rather than the quantum-confinement effect.

Abstract: Cu₂ZnSnS₄ (CZTS) nanocrystals have been synthesized via a simple heating-up method using Cu (acac)₂, Zn (OAc)₂·2H₂O and SnCl₂·2H₂O as metal precursors, and sulfur powder, thioacetamide (TAA), dodecanethiol (DDT) as sulfur sources under same reaction conditions.The influence of different sulfur sources on the phase structure, morphology and optical properties of CZTS nanocrystals were investigated. The phase structure and morphology of the as-obtained nanocrystals were characterized by XRD, Raman, EDS and TEM measurements. The results indicated that the as-prepared CZTS were kesterite structure with S powder and TAA as sulfur sources, while wurtzite CZTS formed with DDT as sulfur source. The different release rate of H₂S with different sulfur sources gave rise to different growth rate of the CZTS NCs. The band-gaps of CZTS NCs synhesized from TAA and DDT showed a blue shift due to the size-induced quantum confinement effect.

Abstract: Gunn oscillations in a GaAs-based planar nanodevice are studied using a two-dimensional ensemble Monte Carlo (EMC) method. Current oscillations with a frequency of about 0.1 THz have been observed. The current oscillations are accompanied by electron domain evolution along the nanochannel. As such, they can be attributed to Gunn Effect. Further study shows that the Gunn oscillations are not only bias-dependent, but also structural-dependent. The threshold voltage and the amplitude of the oscillations are both related to the channel width and the asymmetry of the device structure.

Abstract: On the basis of successfully preparing nanozirconia coating via reasonable spraying technical parameters, the cross section and surface morphology of coating were determined by scan electron microscopy (SEM), and the ceramic particle sizes of coating were determined by transmission electron microscopy (TEM). Experimental results indicate that plasma sprayed zirconia coating possesses typical layer structure of thermal spray coating, in which columnar grains pile up together. Meanwhile, the non-molten nanopowders coexist with the layer structure. In addition, the equiaxial grains exist in the zirconia coating according to TEM, but the grain size is not uniform.