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11.
We demonstrate a transverse electro-optical modulator based on a tiny and irregular octahedral wafer of cubic boron nitride (cBN) crystal that is prepared by hexagonal boron nitride at high pressure and high temperature using nitride as the catalyst. A continuous wave semiconductor laser at the wavelength of 650 nm is used as a light source. A novel electrode fabrication is designed, a developed method different from the conventional transverse electro-optical modulator is introduced and the expression of the intensity of output beam is thought over. We obtain the half-wave voltage based on experiments of transverse electro-optical modulation. The second-order nonlinear optical susceptibility χijk(2)(ω,0)=1.919×10−12 m/V of cBN crystal is calculated by means of the half-wave voltage. 相似文献
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13.
《Materials Research Bulletin》1987,22(6):819-827
Metallic-oxygen deficient compounds in ternary systems MOz.sbnd;La2O3CuO with M = Ca, Sr, Ba have been prepared by coprecipitation and subsequent low-temperature solid-state reaction, as well as by high-temperature reaction from the corresponding oxides and carbonates. Substitution of trivalent La by divalent alka-line-earth ions results in sharp drops in resistivity in the 30 – 40 K range, first discovered for the Ba-La-Cu-O system. Room-temperature X-ray powder diffraction shows the presence of a perovskite-like layer-type phase of K2NiF4-type to be responsible for the high Tc super-conductivity. For single-phase samples of La2CuO4:M composition, the resistivity drop and especially the onset of the diamagnetic susceptibility are enhanced, and occur near the composition where an orthorhombic-to-tetragonal structural phase transition is detected by X-ray diffraction. 相似文献
14.
《Thin solid films》1987,146(3):283-289
The effect of hydrogen as a dilution gas on the deposition of diamond-like carbon by the decomposition of methane in a microwave discharge was studied from surface analysis of the substrate and from plasma diagnostics. When carbon deposited from a CH4-Ar plasma and consisting of large amounts of graphite and small amounts of diamond, was placed in the hydrogen plasma chemical sputtering of carbon to form hydrocarbons and adsorption of hydrogen on the carbon substrate were observed. The reaction occured only on graphite and not on diamond. The effects of hydrogen as a dilution gas on the deposition of diamond-like carbon from CH4-H2 plasma are to cause the formation of CH3 radicals in the plasma, the removal of graphite from the deposit and the adsorption of atomic hydrogen on the deposit as an active participant in the diamond crystallization process. 相似文献
15.
Cuimei Zhao Xin WangYayu Wang Yunxiao ZhaoWeitao Zheng 《International Journal of Hydrogen Energy》2012
Vertically aligned graphene nanosheets have been synthesized by radio-frequency plasma-enhanced chemical vapor deposition on nickel-foam current collectors and that have been used as substrates for cathodic electrodeposition of cobalt hydroxide nanosheets in Co(NO3)2 aqueous solution. Raman spectrum exhibits that high-quality graphene nanosheets have been synthesized. The composites have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and galvanostatic charge/discharge. It indicates that hexagonal Co(OH)2 has a network microstructure, consisting of interlaced sheets with the thickness of 12 nm coated on the graphene nanosheets. The binder-free nano-electrode exhibits excellent pseudocapacitive behavior with pseudocapacitances of 693.8 and 506.2 Fg−1 at current density of 2 and 32 Ag−1, respectively, in a potential range of −0.1–0.45 V. The capacitance can retain about 91.9% after 3000 charge–discharge cycles at 40 Ag−1, which is higher than that of Co(OH)2/Ni foam (after 2000 cycles, 75.5% of initial capacitance remains). The introduction of graphene between Co(OH)2 and Ni foam demonstrates an enhancement of electrochemical stability of the nano-electrodes. 相似文献
16.
Wen CuiDedi Liu Mingguang YaoQuanjun Li Ran LiuZhaodong Liu Wei WuBo Zou Tian CuiBingbing Liu Bertil Sundqvist 《Diamond and Related Materials》2011,20(2):93-96
C60 nanotubes have been synthesized by a solution-solution method. After degassing in a dynamic vacuum, the C60 nanotubes doped with alkali metals by means of vapor evaporation method. Different temperatures have been studied to evaporate the alkali metals for the doping experiments. Raman spectrum was further employed to analyze the doping concentration of the obtained samples. It was found that all three alkali metals (Li, Na and K) used can be efficiently doped into the C60 nanotubes, forming AxC60 nanotubes. The doping concentration of Li, Na changed from low to high level, depending on the experiment temperatures, while K doping always gave saturated doping. The melt points, the ionic sizes and vapor pressures of alkali metals were thought to affect the final doping results. 相似文献
17.
Bowu DongFubo Tian Defang DuanXilian Jin Tian Cui Guangtian Zou 《Diamond and Related Materials》2011,20(3):454-457
We present a first-principles study on a phase of BC7 with Amm2 space-group symmetry (we call o-BC7), which is selected from more than a dozen of candidates via energetic, mechanical and dynamical stabilities within a wide pressure scale from 0 to at least 100 GPa. Our calculated results show that this structure is highly incompressible with large bulk and shear modulus of 388 GPa and 430 GPa, respectively, which is even higher than cubic BN. Further investigations revealed that the Vickers hardness (Hv ≈ 49.5 GPa) is higher than t-BC3 reported recently. And the superconducting critical temperature is calculated to be 38 K, which is comparable to that of MgB2. 相似文献
18.
19.
《Ceramics International》2020,46(8):11499-11507
In this study, NiCo2O4 with different morphologies were fabricated using carriers by homogeneous coprecipitation combined with a sintering method. The phase and microstructure were characterized by XRD, SEM, EDS, TEM and BET, and the catalytic performances were investigated by NaBH4 hydrolysis experiments. These studies revealed that the deposition morphology of NiCo2O4 can be adjusted by using different kinds of carrier templates, and the supported NiCo2O4 samples presented the pine-needle-like, network-like, ball-cactus-like and dandelion-like morphologies respectively. The optimal catalytic activity, durability and stability make the network-like NiCo2O4 an appropriate catalyst for hydrogen generation of NaBH4 hydrolysis. It was found that the network-like NiCo2O4 is the most reusable and durable catalyst for ten consecutive cycles and 100% hydrogen generation conversion rate without obvious decrease among these morphologies. 相似文献
20.
《Ceramics International》2017,43(8):5934-5940
This paper reports a facile two-step synthesis route for the preparation of flower-like ZnO/α-Fe2O3 nanorods (NRs). Flower-like ZnO NRs with the average diameter about 810 nm and length about 4.5 µm were firstly synthesized via a chemical solution method, and then ZnO NRs was coated with a continuous α-Fe2O3 layer to form ZnO/α-Fe2O3 core-shell structure through an ionic-layer adsorption and reaction method. The gas-sensing results show that the ZnO/α-Fe2O3 NRs exhibit excellent sensitivity, selectivity, and response-recovery capacity to ethanol vapor at a low optimum temperature of 240 °C. In particular, compared with pure ZnO NRs and α-Fe2O3 nanoparticles (NPs), the ZnO/α-Fe2O3 NRs show an obvious improvement in gas sensing properties. The substantial improvement of sensing properties may be attributed to the unique microstructure and heterojunction formed between ZnO and α-Fe2O3. 相似文献