巻号一覧
56 巻, 9 号
September
選択された号の論文の8件中1～8を表示しています
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研究
研究
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橋本 等, 孫 正明2009 年 56 巻 9 号 p. 541-545
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスAluminum nitride (AlN) ceramics are indispensable to semiconductor manufacturing processes because of their high thermal conductivities, high corrosion-resistance to halogen gases and plasmas, high strengths and etc. Titanium aluminum nitride (Ti2AlN) is a ceramic showing high electrical conductivity and machinability. A Ti-Al-N ternary equilibrium diagram indicates a two-phase equilibrium region between Ti2AlN and AlN, which motivated the synthesis of AlN-Ti2AlN composites with added electrical conductivity and machinability to AlN ceramics in a wide temperature range. In this study, an approach to the synthesis of AlN-Ti2AlN composites was made by reactive hot-pressing of Ti/Al/TiN/AlN and Ti/AlN powder mixtures, respectively. Before synthesizing the composites, synthesis of single-phase Ti2AlN has been pursued and almost single-phase Ti2AlN was successfully obtained by the reactive hot-pressing of a Ti/Al/TiN powder mixture with a molar ratio of Ti:Al:TiN=1:1:1 and a Ti/AlN powder mixture with the ratio of Ti:AlN=2:1, respectively. However, all attempts to synthesize AlN-Ti2AlN composites by the reactive hot-pressing of a Ti/Al/TiN/AlN powder mixture with the ratio of Ti:Al:TiN:AlN=1:1:1:9 or a Ti/AlN mixture with the ratio of Ti:AlN=1:1 did not succeed, and the cause of these results are discussed.抄録全体を表示PDF形式でダウンロード (777K) -
木村 博2009 年 56 巻 9 号 p. 546-554
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスThis article describes a nanomechanochemistry, from which to set up the phenomenology for the amorphization and nanocrystalline synthesis via non-equilibrium reaction milling in ceramics. When the instrumented rotating-arm reaction ball mill system is used, an amorphization by mechanical alloying (MA) the ceramic powder mixture is monitored through measures of temperature inside the tank and applied torque. This MA process is expressed by Johnson-Mehl-Avrami equation (JMA) of X=Kexp{1−(t−ts)}n with K=Koexp(−Q/kT); JMA exponent (n) is obtained at 0.5 and 1.7 for the nucleation and growth of amorphous (ZrO2-3mol%Y2O3)80(Al2O3)20 and nanocrystalline (ZrO2-3mol%Y2O3)90(Al2O3)10 respectively. On the other hand, for the mechanically driven amorphization of the covalent bond type ceramics, the new formula of d(Vf−V)/dN=−Km(Vf−V) with the repeated impaction number N, as proposed on the basis of the first-order chemical reaction, is validated through a model experiment using planetary ball milling; the reaction rate constant Km increases with decreasing powder amount and temperature, and in order of B4C, ZrB2 and SiC. Furthermore, far from equilibrium reaction milling provides a process window and control methodology for the glass formation in ceramics on the basis of the thermodynamic and kinetic considerations.抄録全体を表示PDF形式でダウンロード (1524K) -
Masahiro Yasukawa, Toshio Kono, Kazushige Ueda, Hiroshi Yanagi, Hideo ...2009 年 56 巻 9 号 p. 555-560
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスPerovskite-type La-doped Ba1-xSrxSnO3 ceramics were prepared by a polymerized complex method followed by a spark plasma sintering technique to examine the thermoelectric properties at high temperatures. For nominal compositions of (Ba1-xSrx)0.95La0.05SnO3 (x = 0.0 - 1.0), La-doped single phases were obtained for x = 0.0, 0.2, 0.4, but a very small amount of La2Sn2O7 was formed for x = 0.6, 0.8, 1.0 and the amount increased with increasing Sr content, indicating that the solubility of La for Ba/Sr site was smaller than 5 mol% for x ≥ 0.6. Dense ceramics with relative densities of 91 - 93 % were obtained for the Ba-containing samples with x = 0.0 - 0.8. Temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each sample with x = 0.0 - 0.8 was an n-type degenerate semiconductor in the measured temperature range of 373 - 1073 K. The Sr content dependence of the σ and S values suggests that the electron carrier concentration decreased with increasing Sr content from x = 0.2 to 0.8, due probably to the decrease in the solubility of La for Ba/Sr site. The thermoelectric power factors S2σ were almost equal among the ceramics with x = 0.0 - 0.8 showing the values from 5.7×10-6 Wm-1K-2 to 1.1×10-4 Wm-1K-2 with increasing temperature, because of a trade-off relation between the σ and S values with respect to the Sr content.抄録全体を表示PDF形式でダウンロード (597K)
特集：ナノテクノロジーが進めるフェライトおよび磁性微粒子材料の高性能化
総報
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山崎 陽太郎2009 年 56 巻 9 号 p. 562
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスPDF形式でダウンロード (147K)
研究
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大塚 勇, 前田 優, 石山 和志, 八木 正昭2009 年 56 巻 9 号 p. 563-567
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスFe-based amorphous powders with high magnetic flux density were fabricated in an extremely high cooling rate of over 106 K/s by SWAP. The composition of the alloys studied were Fex(SiyB1-y)98-xC2 {x=73-85 (at%), y=0.2-0.9 (at%)}. The saturation flux density Bs increased with increasing iron content. For Fe83(Si0.3B0.7)15C2, the Bs value was 1.64 T, which is 31 % higher than that of our previously developed (Fe0.97Cr0.03)76(Si0.5B0.5)22C2 alloy. Furthermore, the Fe81(Si0.3B0.7)17C2 powder core exhibited superior magnetic properties compared with our previously developed Fe76 system powder core. The core loss at 100 kHz for Bm=0.1 T was 450 kW/m3. This value was comparable to that of Fe76 system powder core with a lower flux density.抄録全体を表示PDF形式でダウンロード (662K) -
北本 仁孝, 何 浄沙, 山崎 陽太郎2009 年 56 巻 9 号 p. 568-573
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスThe present paper describes chemical synthesis of ordered alloy FePt nanoparticles with dispersibility into water using a water-soluble polymer ligand, poly(N-vinyl-2-pyrrolidone) (PVP), for biomedical applications such as magnetic sensing devices for diagnostics and magnetic hyperthermia for cancer therapy. Ac magnetic susceptibility takes the maximum value at a temperature near the blocking temperature of magnetic nanoparticles. The blocking temperature of the ordered alloy FePt nanoparticles with high magnetocrystalline anisotropy can be adjusted at around room temperature to improve biomedical performances even though their size is limited in the range of nanometer. The ordered alloy FePt nanoparticles are synthesized by reduction of Fe and Pt organo-metallic compounds with tetraethylene glycol using PVP as a protective agent. Influences of reaction conditions such as temperature and time on crystallite size (particle size) and magnetic properties are investigated. Furthermore, PVP concentration at the synthesis to obtain well dispersed nanoparticle-suspension is examined.抄録全体を表示PDF形式でダウンロード (954K) -
高根 晋, 梅田 秀信, 青木 卓也, 村瀬 琢2009 年 56 巻 9 号 p. 574-577
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスThe effects of Al2O3 addition on the temperature dependency of initial permeability and microstructure of NiCuZn ferrites were investigated. The temperature dependency of initial permeability decreases as Al2O3 addition increases. EPMA analysis revealed that Al2O3 dissolves into the grains of NiCuZn ferrite, but the dispersion is not uniform. By separating the initial permeability into the contributions of spin rotation and domain wall motion, it was found that the temperature dependence of the domain wall motion derived part of permeability decreases as Al2O3 addition increases, while that of the part derived from spin rotation changes little. This indicates that the decrease of the temperature dependency of initial permeability may be attributed to the influence of Al2O3 on the domain wall motion.抄録全体を表示PDF形式でダウンロード (725K) -
Shoichi Nasu, Hidehito Nanto, Akio Nakamura, Etsuji Yamamoto, Toshihik ...2009 年 56 巻 9 号 p. 578-581
発行日: 2009年
公開日: 2009/10/27
ジャーナル オープンアクセスTemperature dependence of time resolved photoluminescence at 512 and 528 μm of uranium glass showed that the decay constant decreased gradually from 265 μs at RT to 24 μs at 282°C. On the other hand, magnetization measurements of the uranium glass showed the paramagnetic behavior with the magnetic moment of 6.48 to 8.24 Bohr magneton in the temperature range of 2 K to 300 K, from which the electronic configuration of U in uranium glass seems to be 5f36d1 or 5f26d2.抄録全体を表示PDF形式でダウンロード (940K)
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