Papers by Keyword: Nanofilm

Abstract: Good dispersion of active catalytic elements, their uniform distribution on the carrier’s surface and availability for neutralised combustion gases are key factors that determine the usability of catalyst cartridges for automotive catalytic reactors. By examining the morphology of oxide films, with SEM/STEM method, obtained by oxidation of foil coated with Pt/Al two-layered system (like laminate), where an Al nanofilm is situated between steel foil and a Pt nanofilm, one can observe forked and plate whiskers growing directly of substrate. Oxide films obtained from Pt+Al composite nanofilms were formed differently (where components are intermixed). These films are marked by chaotic, mutually penetrating fine equiaxed solids and whiskers. In case of composite nanofilms the grain system obtained in the course of deposition contributed to good Pt grain refining, and due to that mostly particles from 3 to 9 nm in conventional diameter were formed. Direct contact between Pt particles and Al particles caused the partial occlusion of Pt particles with oxide in the process of Al oxidation to be effected.

Abstract: The description of different effects observed in nature by only one general equation is the “Holy Grail” for all physicists. This goal has been achieved for characteristic temperatures through a top-down approach (studying size effects from macroscopic laws) and is presented in this chapter. Here, we show the general equation based on the surface area to volume ratio of nanostructures and statistics (Fermi-Dirac or Bose-Einstein) followed by the particles involved in the investigated phenomena. From the distinction between fermions and bosons, so-called particles which follow a Fermi-Dirac or a Bose-Einstein statistics respectively, this equation indicates the universal behaviour of size and shape effects on different material properties like melting, ferromagnetism, vibration and superconduction. The same shape parameter used in this universal equation can be used to determine the melting enthalpy, the phase diagrams of alloys, the energy bandgap and also the creep behavior of nanomaterials. Theoretical predictions show satisfactory agreement with experimental data taken from literature.

Abstract: Nanowires and nanofilms are fundamental building blocks of micro and nano-electronics for both of bottom-up and top-down technologies. Monitoring and recording the mechanical property dynamics at atomic scale are important to understand the atomic mechanism of new and surprising nano-phenomena and design new applications. Through years’ endeavors, we developed tensile and/or bending in-situ atomic-lattice resolution electron microscopy methods and equipments for nanowires and successfully conducted atomic-lattice resolution mechanical tests on individual nano-objects. With this, we observed the brittle materials SiC and Si nanowires (NWs) become highly ductile at room temperature. The crystalline structural evolution processes corresponding to the occurrence of unusual large strain plasticity includes the dislocation initiation, dislocation accumulation and amorphorization as well as the necking of the one dimensional nanowires were fully recorded at atomic scale and in real time. We also expand the experimental methods and equipments to two-dimensional nanofilms. An example of tensile experiment on nano-crystalline Au films is presented. The deformation mechanisms of nano-crystalline gold films were observed at the atomic scale and real-time. At the mean time, an atomic scale the crack blunting behavior was captured and the plastic deformation mechanism of the single nano-crystalline was revealed.

Abstract: A novel structure of nan0Composite consisting of conducting Polyaniline (PANI), graphite nanosheets (NanoGs) and Eu3+ was synthesized through emulsion polymerization. NanoGs were prepared via powdering the expanded graphite with the aid of sonication in aqueous ethanol solution. Then NanoGs and rare earth ions (Eu3+) were directly organised with sonication, using p-toluene-sulfonic acid (P-TSA) as an emulsifier and dopant, (NH4)2S2O8 as inducing reagent and the polymerization of aniline monomer simultaneously. The product was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Fouier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). From the thermogravmetric analysis, the introduction of NanoGs and rare-earth ions (Eu3+) exhibited a beneficial effect on the thermal stability of pure PANI.

Abstract: The gauge factor and nonlinearity of 80nm polysilicon nanofilms with different doping concentration were tested. The experimental results show that, from 8.1×1018cm-3 to 2.0×1020cm-3, the gauge factors first increase then decrease, which like the common polysilicon films (thickness is larger than 100nm). From 2.0×1020cm-3 to 7.1×1020cm-3, the gauge factors do not change with doping concentration almost, which can be explained by tunneling piezoresistive theory. When doping concentration is low than 4.1×1019cm-3, the nonlinearities are big, and the nonlinearities become small when doping concentration is high than 4.1×1019cm-3. The nonlinearity is related to the occupied condition of trapping states in grain boundary. The longitudinal gauge factor and nonlinearity are smaller than transverse ones. Take the gauge factor and nonlinearity both into consideration, the optimal doping concentration should be 4.1×1019cm-3. The conclusions are very useful for design and fabrication of polysilicon nanofilms piezoresistive sensor.

Abstract: The polysilicon nanofilms have significant piezoresistive characteristics. In this paper, an analysis of tunneling piezoresistive effect of p-type polysilicon nanofilms is presented based on the experimental data. The analysis results show that the tunneling piezoresistive effect is much remarkable than piezoresistive effect of neutral region, and the former is about 1.3 to 1.5 times of the latter. The higher is doping concentration, the more remarkable tunneling piezoresistive effect is. This advantage can be utilized to improve the temperature characteristics of polysilicon piezoresistive sensor.

Abstract: In the present work two different hydroxyapatite nanofilms (50 and 100 nm thick) have been successfully deposited on titanium implants that were previously laser macrostructured in order to assess the influence of the thickness of nanometric calcium phosphate coatings on the osseointegration. Cylindrical implants were tested in a sheep tibia model together with titanium alloy controls achieving very good osseointegration results. Laser macrostructured titanium alloy implants have shown improved bone regeneration when coated with nanometric films of carbonated HA. The pulsed laser deposited nanofilm has promoted bone in-growth deep into the laser ablated craters. There were no significant differences between the two coating thicknesses, neither when assessed with electron microscopy or classical optical methods. This result suggests that the 50 nm coating is as effective as the 100 nm one, therefore implying that the thickness limit for such a bioactive layer to stimulate bone growth may be even further below.

Abstract: We investigate the electrical conductive poly(3,4-ethylenedioxythiophene) (PEDOT) nanofilms and micropatterning prepared by vapor-phase polymerization method using self-assembling teacnique. The thin conductive films were uniformly fabricated between 20 and 100 nm, there surface resistance wasenhanced until to 102
/square, and the light-transmittance were also increased as up to 95 %. We report a fabrication of electrically conducting PEDOT pattern on a electrically insulating substrate using a microcontact printing method. Then, patterns are successfully obtained with line widths down to 3
.

Abstract: The Ce4+-modified titania nanofilm was deposited onto mild steels by the sol-gel method. The effect of the film on protecting mild steels from oxidation was studied by means of oxidation test, SEM and XRD. It was found that the anti-oxidation effect is increased by Ce4+ modifying and with increasing layer number. When oxidized below 600 oC, the Ce4+-modified double-layer titania nanofilm possesses an excellent anti-oxidation performance that is comparable with that of the stainless steel.