Papers by Keyword: Nanostructure

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Authors: Tian Hong Guo, Juan Li, Yong Cai Zhang, Zhan Jun Yang
Abstract: An in situ thermal oxidation strategy was proposed for synthesizing different SnO2 nanostructures, using our homemade SnS2 nanoplates as a precursor. The characterization results from X-ray diffraction, energy dispersive X-ray spectroscopy, and field emission scanning electron microscope revealed that the heating temperature played an important role in the microstructure and composition of the resultant products. By heating the SnS2 nanoplates in air at 400, 600 and 800 °C for 5 h, nanoplates, a mixture of nanoplates and nanoparticles, and nanoparticles of SnO2 were synthesized, respectively. The residual S was about 2.2 mol % in the product synthesized at 400 °C, while no residual S was detected in the products synthesized at 600 and 800 °C.
Authors: Radosław Zaleski, Jacek Goworek
Abstract: The ordering of n-nonadecane confined in the pores of MCM-41 silica was investigated by Positron Annihilation Lifetime Spectroscopy. No irradiation effects caused by the positron source were observed. The ortho-positronium components found in the lifetime spectra correspond to the free volumes observed in the bulk alkane plus additional space at the interface between n-nonadecane and the silica wall. Phase transitions rigid-rotator and rotator-liquid were shifted towards lower temperatures by 28 and 16 degrees respectively.
Authors: P.S. Pa
Abstract: A bluge rotational tool has been developed as an effective precision electrochemical removal for the thin film nanostructures from LCD panels. This ultra-precise process effectively removes defective Indium-Tin-Oxide layers allowing LCD panels to be returned to the production line and significantly reduces costs. In the current experiment a 7th Generation TFT-LCD panel was used. A high rotational speed of the cheek rotational tool elevates discharge mobility and improves the removal effect. A negative electrode of large diameter with a small end radius provides higher current density and also improves the removal affect. Pulsed direct current can improve the effect of dregs discharge and is advantageous when combined with a higher electric power. A fast feed combined with a high current flow results in very effective removal of the color filter layer. This novel design using electrochemical removal as a precision recycling process for removing ITO layers from LCD panels is clean, effective and very fast.
Authors: Taek Kyun Jung, T.J. Sung, Mok Soon Kim, Won Yong Kim
Abstract: Al-8Fe-2Mo-2V-1Zr alloy powders were prepared by gas atomization and melt spinning method. In melt spinning technique, melt spun ribbons were pulverized by a speed rotor mill to make a powder shape. In order to produce a bulk form, powders were canned and hot extruded in the extrusion ratio of 25 to 1 at 693K. For the gas atomization and hot extrusion processed bulk material, equiaxed grains with the average size of 400 nm and finely distributed dispersoids with their particle sizes ranging from 50nm to 200nm were observed to display a characteristic nano-structured feature over the entire region. For the melt spun and hot extrusion processed alloy, a refined microstructural feature consisting of equiaxed grains with the average size of 200 nm and fine dispersoids with their particle sizes under 50 nm appeared to exhibit a difference in microstructure. Yield strength of the latter alloy was higher than that for the former alloy up to elevated temperatures. The maximum yield strength was measured to about 800 MPa at room temperature for the latter alloy.
Authors: Sergey Prokoshkin, Vladimir Brailovski, Karine Inaekyan, Andrey Korotitskiy, Sergey Dubinskiy, Mikhail R. Filonov, Mikhail Petrzhik
Abstract: The processes of structure formation in Ti-Ni and in Ti-Nb-Zr, Ti-Nb-Ta shape memory alloys (SMA) under thermomechanical treatment (TMT) were studied. The TMT comprised cold rolling with true strains from e=0.25 to 2 and post-deformation annealing. Differences in these processes between two groups of alloys are considered. The main conclusions are as follows: nanostructures created by TMT are useful for radical improvement of the SMA functional properties, and an optimum nanostructure (nanocrystalline structure, nanosubgrained structure or theirmixture) should be selected by taking into account other structural and technological factors.
Authors: Run Fu Li, Hua Li, Hui Ying Chen, Jian Xin Xia, Chun Lin Long
Abstract: Monodisperse nickel phosphide (Ni5P4) nanoparticles supported on carbon (Ni5P4@C) were in situ synthesized by one step solution-phase route, in which the mixture of trioctyloxide (TOPO) and trioctylphosphine (TOP) was used as solvent, capping agent and phosphor source. Ni5P4nanocrystals were in situ coupled by active carbon simply adding the carbon to the reaction solution. The as-prepared Pt-free Ni5P4 nanocrystals exhibit the enhanced electrocatalytic activity toward hydrogen oxidation reaction (HOR) compared to pure commercial Ni nanoparticles. Therefore, the obtained Ni5P4@C nanocatalyst appears to be promising non precious metal electrocatalysts for HOR.
Authors: Hui Zhang
Abstract: α-FeOOH nanorods were fabricated via a one-step hydrothermal approach using iron nitrate hydrate (Fe(NO3)3·9H2O) as iron source, cetyltrimethylammonium bromide (CTAB) as a template and acetic acid (CH3COOH) solution as solvent. XRD, SEM, TEM, and TGA were applied to characterize the samples. The as-prepared α-FeOOH nanorods are around 50 nm in diameters and 1 µm in length. The aspect ratio is 20. The XRD and TEM results indicated that both CTAB and CH3COOH were crucial for the formation of α-FeOOH nanorods. The heat treatment at the temperature of 250°C led to the transformation of α-FeOOH to α-Fe2O3, and the crystal phase transformation was completed at 340°C. The lower transformation temperature compared to bulk α-FeOOH could be attributed to the decreased size of the as-prepared sample.
Authors: Ya Hui Zhang, Xi Cheng, Qing Wang
Abstract: A low-temperature precursor sulfuration route has been established to prepare metal sulfides with different nanostructures during the synthesis of nickel sulfide. The advantages of the low-temperature precursor sulfuration route were testified by the synthesis of different metal sulfides ( lead sulfide, zinc sulfide and cobalt sulfide). It offers a novel path to the preparation of other metal sulfides.
Authors: Ming Horng Su, Hung Chang Chen
Abstract: This paper studies the phase transitions of Cu and Ni alloys as they cool from melting temperature to room temperature under high-pressure conditions. The interatomic forces acting between the atoms are modeled by the tight-binding potential. Control over the environmental pressure and the cooling temperature is maintained by a canonical ensemble (N, P, T) system. The numerical results confirm that the metal phase transition is influenced significantly by the pressure conditions, even in the case of pure Cu and Ni metals. Three specific transition pathways are identified for the Cu and Ni alloys as they cool from melting temperature to room temperature, namely a transition at the melting temperature to a crystalline structure, a transition at the glass transition temperature to a glass (amorphous) structure, and finally solidification at the melting temperature followed by a subsequent transition at the glass transition temperature. The results reveal that glass transition generally occurs at lower pressures in alloys with higher Cu compositions, while glass transition following prior solidification tends to takes place at higher pressures in alloys with higher Ni compositions.
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