Advanced Materials Research Vols. 1004-1005

Abstract: The bulk nanocrystalline aluminum are fabricated by cryomilling and hot-press sintering. The internal friction (IF) and relative dynamic modulus measurements in the nanocrystalline aluminum (Al) have been made using a multifunction internal friction apparatus (MFIFA) at low frequencies (0.2-3.0 Hz) over the wide temperature ranges from room temperature to 450 °C, while continuously changing-temperature forced vibration measurement. In the temperature spectrums of IF during heating process and cooling process, a distinct IF peak is found. Corresponding to the IF peak, the relative dynamic modulus decreases rapidly. The peak temperature of the IF peak shifts towards higher temperature with increasing frequency, i.e., the IF peak seem due to the thermal activated relaxation process. The IF peak is a grain boundary IF peak, which is associated with the diffusive grain boundary of Al/Al. Its activation energy has been calculated to be 2.21±0.04×10^-19 J and the pre-exponential factor is 10^-14 s in IF measurements.

Abstract: Silver dendrites were synthesized via a simple and straightforward strategy based on the galvanic displacement between Ag ions and aluminum foil in the room temperature. Because the presence of Al₂O₃ thin layer on the surface of aluminum foil, the NaCl was added to accelerates the reaction rate. The formed Ag dendrites was characterized by UV-vis spectroscopy, SEM and XRD. The as-prepared Ag dendrites were developed as a catalyst by mixed with reduced graphene oxide and used for degradation of methylene blue when the presence of NaBH₄. Moreover, the optimal conditions of degradation were also investigated.

Abstract: Porous CeO₂ nanostructures were synthesized by a simple template method using cotton fibers as biomaterial template. The phase structure and morphology of the product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM). The UV-blocking property was evaluated by UV-Vis spectrophotometry. Experimental results showed that the as-synthesized CeO₂ was in a cubic fluorite structure and presented fiber-like structure. The fiber-like CeO₂ nanostructures completely recorded the original morphology of cotton fibers, which consisted of large amounts of coalescent CeO₂ nanoparticles with average particle size in the range of 6-10 nm. The UV test result showed that the UV transmittance of the product was closer to zero in the wavelength below 350 nm, indicating that the product exhibited excellent UV-blocking property.

Abstract: The relations between specific surface area, morphologies and collection rate, feeding rate of Cu-Ag alloy nanopowders prepared by plasma induction system were studied by specific surface area tester and SEM. The results show that with the increase of powder feeding rate from 300g/h to 500g/h and to 800g/h, the collection rate decreases from 59.1% to 47.2% and to 46.1%, respectively, and the specific surface area accordingly decreases from 9.25m²/g to 7.17m²/g and to 5.45m²/g.

Abstract: An eutectic NiAl–1.5 at.% W alloy prepared by using directionally solidified (DS)was employed as a source for producing W-nanowires. Several growth rate of 8,15,25/s was respectively used at a temperature gradient of ~240 K/cm in a Bridgman-type directional solidification furnace. A combined stability diagram was applied to predict proper conditions for the selective dissolution of NiAl matrix to get W-wires. Etching in a mixture of HCl:H₂O₂ released parallel aligned W-nanowires with a wire diameter of ~500 nm. Different morphologies, such as nanobelts, lotus-shaped, conical of W-nanowires are obtained at the different conditions.

Abstract: The Paper provides preliminary results with the aim to determine a range of the local scientific activity in the development of advanced technologies on a global scale. Analysis on ranking is made in the Baltic Sea Region accepted as the main limitation of the Paper. The applied methods are logical approach, analysis of the literary sources, assessment of the indicators (including financing, scientific and innovative activities ratios), its dynamics in the scientific field and business arena. The enclosed analytical data ensure the value of the Paper. Among the main findings are: available data for the economic assessment of the nanotechnologies in Latvia are of a general character, limited or controversial. Recently, Latvia has had both the lowest and the highest rankings.

Abstract: The silver nanoparticles (Ag NPs) with average diameter of 84nm are synthesized via a simple liquid phase reduction method in the mixture of water and ice. The conductive ink with good performance is formulated using the synthesized Ag NPs and its average sheet resistance reaches to 0.62Ω/□. Furthermore, the grid transparent conductive films (TCFs) with three different geometries are fabricated using the formulated conductive ink through flexographic printing, and the transparent and conductive properties are analyzed and compared, resulting in the comprehensive quality Q of 20um/ 400um hexagon grid (3.79) is relatively the highest.

Abstract: The controllable synthesis of special shape of nanoparticles with uniform size was most important for some special applications. In this work, we prepared silver nanocubes by Na₂S-mediated polyol synthesis using AgNO₃ as precursor, polyvinyl pyrrolidine(PVP) as capping agent and ethylene glycol(EG) as solvent and reductant under the protection of Ar characterized by SEM, UV-vis, DLS and Zeta potential. Silver nanocubes were successfully controllably obtained via optimizing the reaction conditions, such as the rate of Ar initially after 50 min pre-heating and subsequently after the addition of AgNO₃ solution，the volume of 3 mM Na₂S solution. The results showed that silver nanocubes with edge length of 50 nm and sharp corners were achieved at 230μL 3mM Na₂S solution added under a Ar rate of 1000 ml/min.

Abstract: Carbon nanotubes (CNTs) have been widely studied for their unique size-dependent electrical, mechanical, and chemical properties. However, CNTs need to be precisely positioned in complex device structures. Dielectrophoresis (DEP) is an effective and practical method for precise assembly of CNTs. In this paper, the researches on simulation of precise positioning of CNTs by DEP are reviewed. Single electrode pairs include those with round, triangle, and rectangular tip shapes and electrode arrays such as comb electrodes are also taken accounted. The moving trajectories of CNTs during DEP from the selected literature are introduced. The effect of floating electrodes on precise manipulation of CNTs is examined as well.