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101.
T. Shin-ike T. Sakai Tetsuo Sakai G. Adachi J. Shiokawa 《Materials Research Bulletin》1977,12(7):685-688
The nature of the V/1bO/1bV interaction of the perovskite type rare-earth vanadites were studied by spectroscopic methods. Infrared and ultraviolet analyses revealed that the V/1bO bond length became shorter and that the V/1bO bond strength increased, as a function of the atomic number of lanthanide elements in LnVO3. Judging from the x-ray fluorescent spectra of oxygen-Kα, the energy level of O2? (pπ) orbitals of the heavier rare-earth vanadites was lower than that of the lighter rare-earth vanadites. 相似文献
102.
Generation of free radicals (mechano-radicals) by the milling of alumina powder at 77 K was demonstrated by ESR. After milling of alumina in the presence of ethylene (simultaneous milling) at 77 K, polyethylene-propagating radicals instead of the alumina mechano-radicals were detected by ESR. Also the contact of ethylene with the milled alumina converted alumina mechano-radicals into polyethylene propagating radicals at a temperature above the melting point of ethylene. The products extracted by hot toluene from the simultaneous milling were identified by IR to be polyethylene, and their molecular weights were roughly 10,000. The residues after the extraction were bonded with the alumina. Polypropylene was also produced by a similar method of milling of alumina in the presence of propylene. The obtained polyproylene was atactic, and its molecular weight was about 400. 相似文献
103.
Nonstoichiometric , which exhibits a metallic behavior, was obtained by heating an insulating Gd2S3 at various temperatures under a vacuum. Electrical and magnetic properties of the samples obtained have been investigated from 4.2 K to 300 K. A maximum in resistivity was observed in the curve of resistivity vs. temperature. The temperature TP, at which the maximum emerged, was very close to the Curie temperature TC for the sample. An increase in resistivity at TP, Δ?, is proportional to ?P exp (), where ?P is the resistivity obtained by the extrapolation from the linear portion to TP in the ? vs. T curve. Using the relationship obtained, a model based on the formation of magnetic polaron was proposed for this system. 相似文献
104.
M. Sato T. Noji T. Adachi T. Kawamata H. Akagawa Y. Koike 《Journal of Low Temperature Physics》2003,131(3-4):293-297
For La2–x
Sr
x
CuO4 single-crystals in the underdoped and overdoped regimes, we have measured the electrical resistivity along the c-axis,
c
, under constant magnetic fields, changing the field direction in the ab-plane. At x=0.08, 0.12 and 0.16 in the underdoped and almost optimally-doped regimes, clear anisotropy of
c
with the fourfold symmetry in the ab-plane has been observed. This symmetry is regarded as the fourfold symmetry of the upper critical field, H
c2, and explained as being mainly due to the anisotropy of the superconducting energy gap owing to the dx
2-y
2 pairing. The magnitude of the fourfold component of H
c2, H
c2/H
c2, is largest in x=0.08 among the three crystals. At x=0.20 in the overdoped regime, no clear fourfold symmetry has been observed. It appears that the fourfold symmetry is easy to observe in the underdoped regime rather than in the overdoped regime. 相似文献
105.
Hiroyuki Sasakura Yoshiya Akagi Shigeki Tsukui Takashi Oka Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2007,20(5):381-386
Bi-based superconducting compounds with the 2222 structure has been already synthesized in the Bi2Sr2- (Ln1−x
Ce
x
)2Cu2O10+y
(Ln = Sm, Eu, and Gd) systems. One of the characteristics of these compounds is the existence of the fluorite-like (Ln1−x
Ce
x
)2O2 block between two CuO5 pyramids in the crystal structure. The tetravalent ions of Ce4+ are reported to be necessary to stabilize the 2222 structure. Recently, we have discovered that the Bi-2222 phase could be
composed in the Bi2Sr2(Ln2−x
Zr
x
)Cu2O
z
(Ln = Sm, Eu, Gd, and Dy) systems, where Zr4+ is used as a new tetravalent ion stabilizing the 2222 structure in stead of Ce4+. In the new system, nearly single 2222 phase samples have been obtained at the nominal composition of x=0.5 (Ln = Sm, Eu, and Gd) and in the range of 0.1≤x≤0.3 (Ln = Dy). Among them, the sample with Ln = Gd has the smallest resistivity at 273 K. But it is a semiconductor, and
the conduction process at low temperatures is assumed to be followed by a two-dimensional VRH. The experimental results for
the Gd samples with a partial substitution of Pb for Bi in the Bi2Sr2(Gd2−x
Zr
x
)Cu2O
z
system are also reported. 相似文献
106.
A new hybrid multi-access technique, called delay-time/code division multi-access (DT/CDMA), is proposed. Multiplexing is accomplished in both the delay-time domain and code domain. Delay-time division multiplexing is achieved by assigning different cyclic time delays to the same spreading sequence. At a receiver, frequency-domain equalisation, despreading, and demultiplexing are performed simultaneously in the frequency domain. The bit error rate performance when using the proposed DT/CDMA in a frequency-selective Rayleigh fading channel is evaluated by computer simulation. 相似文献
107.
Modifications of indium-tin-oxide (ITO) and copper phthalocyanine (CuPc) layers by heat treatment aimed at lowering driving voltage in organic light-emitting diodes (OLEDs) are examined. Significant changes were observed in the surface morphology and carrier injection properties of ITO and CuPc layers after annealing at T = 250 °C for 0-60 min in a glove box. In the case of ITO annealing, although the ITO work function gradually decreased and the surface of the ITO layer became smoother than that of an unannealed ITO layer, we observed an appreciable decrease in the driving voltage with an increase in annealing time. In the case of CuPc annealing, on the other hand, we observed deterioration of the OLED's characteristics. All devices demonstrated an increase in driving voltage due to the pronounced crystallization of the CuPc layer. 相似文献
108.
A gas flow deposition (GFD) system was developed to manufacture large-scale organic light-emitting diodes (OLEDs). A N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (α-NPD) thin film with a high purity of 99.97% was obtained using the GFD system. The film properties such as morphology, and electrical and optical characteristics were almost the same as those of films made by conventional vacuum thermal evaporation. 相似文献
109.
110.
Hirotaka SoHirofumi Watanabe Masayuki YahiroYu Yang Yuji OkiChihaya Adachi 《Optical Materials》2011,33(6):755-758
In this study, we synthesized the new spirobifluorene derivatives; hexylbiphenyl-spirobifluorene (HBP-Spiro) and triphenylamine-spirobifluorene (TPA-Spiro) and demonstrated the operation of a distributed-feedback polymer waveguide blue laser. In addition, we investigated the optical and lasing properties of spirobifluorene derivatives including photostability. The experimental slope efficiency and the energy threshold of a HBP-Spiro-doped waveguide laser were 3.6% and 1.9 μJ, respectively. An operation lifetime of 27,000 shots was obtained for a pump-pulse duration of 1.2 ns and energy of 3.0 μJ at a wavelength of 355 nm. 相似文献