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951.
Junji Saida Rui Yamada Masato Wakeda Shigenobu Ogata 《Science and Technology of Advanced Materials》2013,14(1):152-162
AbstractStructural rejuvenation in metallic glasses by a thermal process (i.e. through recovery annealing) was investigated experimentally and theoretically for various alloy compositions. An increase in the potential energy, a decrease in the density, and a change in the local structure as well as mechanical softening were observed after thermal rejuvenation. Two parameters, one related to the annealing temperature, Ta/Tg, and the other related to the cooling rate during the recovery annealing process, Vc/Vi, were proposed to evaluate the rejuvenation phenomena. A rejuvenation map was constructed using these two parameters. Since the thermal history of metallic glasses is reset above 1.2Tg, accompanied by a change in the local structure, it is essential that the condition of Ta/Tg ≥ 1.2 is satisfied during annealing. The glassy structure transforms into a more disordered state with the decomposition of icosahedral short-range order within this temperature range. Therefore, a new glassy structure (rejuvenation) depending on the subsequent quenching rate is generated. Partial rejuvenation also occurs in a Zr55Al10Ni5Cu30 bulk metallic glass when annealing is performed at a low temperature (Ta/Tg ~ 1.07) followed by rapid cooling. This behavior probably originates from disordering in the weakly bonded (loosely packed) region. This study provides a novel approach to improving the mechanical properties of metallic glasses by controlling their glassy structure. 相似文献
952.
Tominaga M Han L Wang L Maye MM Luo J Kariuki N Zhong CJ 《Journal of nanoscience and nanotechnology》2004,4(7):708-711
This paper reports novel findings of an investigation of the formation of water-soluble iron oxide nanoparticles from iron-storage protein ferritin. The strategy couples thermal removal of the protein shell on a planar substrate and subsequent sonication in aqueous solution under controlled temperature. Advantages of using ferritin as a precursor include well-defined core size, core composition, water-solubility and processibility. The formation of the nanoparticles was characterized using TEM, UV-Vis and FTIR techniques. Iron oxide nanoparticles in the size range of 5-20 nm diameters were produced. In addition to thermal treatment conditions, the sonication temperature of the nanoparticles in water was found to play an important role in determining the resulting particle size. This simple and effective route has important implications to the design of composite nanoparticles for potential magnetic, catalytic, biomedical sensing and other nanotechnological applications. 相似文献
953.
Ryo Kuroda Zhengxin Liu Yasuhiro Fukuzawa Yasuhito Suzuki Masato Osamura Shinan Wang Naotaka Otogawa Teruhisa Ootsuka Takahiro Mise Yasushi Hoshino Hisao Tanoue 《Thin solid films》2004,461(1):34-39
For the epitaxial growth of thick β-FeSi2 films, we fabricated ultrathin β-FeSi2 template layers (thinner than 20 nm) on Si (111) substrates with different methods. Surface morphology and crystallinity of the template layers were found to be dependent on the surface conditions of the substrate and the fabrication method. It was revealed that to form a smooth and continuous template, a hydrogen-terminated surface was better than that covered with a several-nanometer oxide layer. Using this surface, continuous (110)/(101)-oriented epitaxial template was obtained by depositing 6-nm iron at 400 °C and subsequent in situ annealing at 600 °C in MBE chamber, namely, a reaction deposition epitaxy (RDE) method. Co-deposition of iron and silicon with atomic ratio of Fe/Si=1/2 allowed the forming of template layers at further low temperature. Co-deposited template layers exhibited better crystallinity and morphology than those prepared by RDE. By using the optimized template layer, we succeeded in growing high-quality thick β-FeSi2 films on Si (111) substrates with sharp β-FeSi2/Si interface. 相似文献
954.
Masato Miyake 《Thin solid films》2007,515(9):4258-4261
Characteristics of nano-crystalline diamond (NCD) thin films prepared with microwave plasma chemical vapor deposition (CVD) were studied in Ar/H2/CH4 gas mixture with a CH4 gas ratio of 1-10% and H2 gas ratio of 0-15%. From the Raman measurements, a pair of peaks at 1140 cm− 1 and 1473 cm− 1 related to the trans-polyacetylene components peculiar to nano-crystalline diamond films was clearly observed when the H2 gas ratio of 5% was added in Ar/H2/CH4 mixture. With an increase of H2 gas content up to 15%, their peaks decreased, while a G-peak at roughly 1556 cm− 1 significantly increased. The degradation of NCD film quality strongly correlates with the decrease of C2 optical emission intensity with the increase of hydrogen gas contents. From the surface analysis with atomic force microscopy (AFM), it was found that grain sizes of NCD films were typically of 10-100 nm in case of 5% H2 gas addition. 相似文献
955.
Hiroki Ago Ei-ichiro Uchimura Takeshi Saito Satoshi Ohshima Naoki Ishigami Masaharu Tsuji Motoo Yumura Masato Miyake 《Materials Letters》2006,60(29-30):3851-3854
We demonstrate that an aligned multi-walled carbon nanotube array can immobilize Hela cells through insertion of the nanotube tips into the cell. The cells were immobilized by pressing onto the nanotube array with the aid of mild centrifugal force. The nanotube array fixed a much larger number of cells compared with the flat surface of a Si substrate, indicating strong binding force of the aligned nanotubes toward the cell. This is the first example of mechanical cell immobilization, which offers future applications of the nanotube array for cellular biology, tissue engineering, and biomolecular devices. 相似文献
956.
Masato Sasaki Hirokatsu Umegami Masayoshi Yamamoto 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(Z2):S144-S145
Silicon carbide schottky barrier diodes (SiC SBDs) have much better characteristic than Si PiN diode in high voltage applications because SiC SBDs do not have recovery effect. However, simple replacing is not the most effective way. In a boost converter, the power loss caused by the SiC SBD can be divided into the conduction loss of the SiC SBD and the loss caused by the energy stored in the junction capacitance of the SiC SBD. Therefore analysis of not only the conduction loss but also the loss caused by the energy stored in the junction capacitance of the SiC SBD can realize the SiC SBD selection to improve the efficiency of the boost converter. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献