318 resultados para Raney-Ni
Resumo:
采用传统熔融冷却的方法制备了透明Ni^2+掺杂ZnO-Al2O3-SiO2系玻璃,结合X-射线、吸收和荧光等测试手段,研究了不同热处理温度对Ni^2+掺杂透明ZnO-Al2O3-SiO2系微晶玻璃光学性质的影响。由X-射线衍射谱鉴定出微晶玻璃中析出的晶相为ZnAl2O4微晶,其尺寸在13nm以下。玻璃中没有发现近红外发光,而在微晶玻璃中存在宽带近红外发光,其可归属为八面体六配位Ni^2+离子的^3T2g(^3F)激发态向^3A2g(^3F)基态的跃迁。随热处理温度升高发光强度增强,而发射峰位则发生蓝移;荧
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采用三种不同的双光记录方案进行了LiNbO3:Fe:Ni晶体全息存储实验.详细研究了饱和衍射效率、固定衍射效率、动态范围和记录灵敏度,以及退火条件对记录的影响。结果表明,氧化LiNbO3:Fe:Ni晶体的饱和衍射效率、固定衍射效率和记录灵敏度比其他报道的双掺杂LiNbO3晶体高。结合掺杂能级图,理论分析了LiNbO3双掺杂晶体深陷阱中心能级的相对位置及其微观光学参量对全息记录性能的影响。LiNbO3:Fe:Ni晶体有望成为一种新的高效率非挥发全息存储材料。
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分别采用514nm绿光、488nm蓝光和390nm紫外光作为敏化光,633nm红光作为记录光,详细研究了敏化光波长对氧化(Fe,Ni):LiNbO3晶体全息记录性能的影响。结果表明:随着敏化光波长的逐渐减小,氧化(Fe,Ni):LiNbO3晶体的非挥发全息记录性能逐渐优化,390nm紫外光是这三种敏化光中最优的敏化光。考虑敏化光的吸收,为了在双中心全息记录中获得最优的性能,应当选择合适波长的敏化光:一方面短波长敏化光能有效地敏化深中心;另一方面短波长敏化光的吸收太强(如对光折变效应无用的基质吸收),不能沿
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By sensitizing with 514 nm green light, 488 nm blue light and 390 nm ultraviolet light, respectively, recording with 633 nm red light, effect of wavelength of sensitizing light on holographic storage properties in LiNbO3:Fe:Ni crystal is investigated in detail. It is shown that by shortening the wavelength of sensitizing light gradually, nonvolatile holographic recording properties of oxidized LiNbO3:Fe:Ni crystal is optimized gradually, 390 nm ultraviolet light is the best as the sensitizing light. Considering the absorption of sensitizing light, to obtain the best performance in two-center holographic recording we must choose a sensitizing wavelength that is long enough to prevent unwanted absorptions (band-to-band, etc.) and short enough to result in efficient sensitization from the deep traps. So in practice a trade-off is always needed. Explanation is presented theoretically. (c) 2005 Elsevier GmbH. All rights reserved.
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本文结合测试分析光学一机械桁架悬臂结构的振动特性,为用MATLAB控制NI采集卡实现高精度数据采集与分析功能提供了实例参考,也为MATLAB控制其它高性能采集卡提供了有益的操作思路。
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Two kinds of nickel(II) and copper(II) P-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated. (c) 2006 Elsevier B.V. All rights reserved.
Resumo:
用扫描电镜(SEM)观察了化学沉积Ni-P合金薄膜/单晶硅基体的结构与颗粒度,利用X射线衍射(XRD)技术测试了其化学沉积后的残余应力,测量了激光热处理后残余应力的变化规律,分析了残余应力对磨损性能及界面结合强度的影响。实验结果表明,化学沉积Ni-P合金薄膜/硅基体的残余应力均表现为拉应力,经过激光热处理后残余应力发生了变化,由高值的拉应力变为低值的拉应力或压应力;薄膜残余应力对其磨损性能有明显的影响,其磨损量随着残余应力的减小而减小;薄膜与基体结合强度随着残余应力的增大而减小,合理地选择激光热处理参数可
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The emission intensity of Ni2+ at 1200 nm in transparent ZnO-Al2O3-SiO2 glass ceramics containing ZnAl2O4 nanocrystals is improved approximately 8 times by Cr3+ codoping with 532 nm excitation. This enhanced emission could be attributed to an efficient energy transfer from Cr3+ to Ni2+, which is confirmed by time-resolved emission spectra. The energy transfer efficiency is estimated to be 57% and the energy transfer mechanism is also discussed. (C) 2008 Optical Society of America.
Resumo:
The near-infrared emission intensity of Ni2+ in Yb3+/Ni2+ codoped transparent MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics could be enhanced up to 4.4 times via energy transfer from Yb3+ to Ni2+ in nanocrystals. The best Yb2O3 concentration was about 1.00 mol%. For the Yb3+/Ni2+ codoped glass ceramic with 1.00 mol% Yb2O3, a broadband near-infrared emission centered at 1265 nm with full width at half maximum of about 300 nm and lifetime of about 220 mu s was observed. The energy transfer mechanism was also discussed. (C) 2008 Optical Society of America.
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Transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics without and with Ga2O3 were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga2O3 addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni2+-doped glass ceramics was largely enhanced by Ga2O3 addition which could mainly be caused by increasing of Ni2+ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga2O3 content was all more than 200 nm. The emission lifetime increased with the Ga2O3 content and the longest lifetime is about 250 mu s. The Ni2+-doped transparent glass ceramics with Ga2O3 addition have potential application as broadband optical amplifier and laser materials. (C) 2007 Elsevier Ltd. All rights reserved.
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Transparent Ni2+-doped MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics were fabricated. The precipitated nanocrystal phase in the glass ceramics was identified by X-ray diffraction and transmission electron microscope. Broadband near-infrared emission centered at 1220 nm with full width at half maximum of about 240 nm and lifetime of about 250 mu s was observed with 980 nm excitation. The longer wavelength emission compared with Ni2+-doped MgAl2O4 crystal was attributed to the low crystal field occupied by Ni2+ in the glass ceramics. The present Ni2+-doped transparent glass ceramics may have potential applications in broadband optical amplifiers. (c) 2007 Elsevier B.V. All rights reserved.
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Polycrystalline Zn1-xNixO diluted magnetic semiconductors have been successfully synthesized by an auto-combustion method. X-ray diffraction measurements indicated that the 5 at% Ni-cloped ZnO had the pure wurtzite structure. Refinements of cell parameters from powder diffraction data revealed that the cell parameters of Zn0.95Ni0.05O were a little bit larger than ZnO. Transmission electron microscopy observation showed that the as-synthesized powders were of the size similar to 60 nm. Magnetic investigations showed that the nanocystalline Zn0.95Ni0.05O possessed room temperature ferromagnetisin with the saturation magnetic moment of 0.1 emu/g (0.29 mu(B)/Ni2+). (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Observation of room-temperature ferromagnetisin in Fe- and Ni-co-doped In2O3 samples (In0.9Fe0.1-xNix)(2)O-3 (0 <= x <= 0.1) prepared by citric acid sol-gel auto-igniting method is reported. All of the samples with intermediate x values are ferromagnetic at roomtemperature. The highest saturation magnetization (0.453 mu B/Fe + Ni ions) moment is reached in the sample with x = 0.04. The highest solubility of Fe and Ni ions in the In2O3 lattice is around 10 and 4 at%, respectively. The 10 at% Fe-doped sample is found to be weakly ferromagnetic, while the 10at% Ni-doped sample is paramagnetic. Extensive structure including Extended X-ray absorption fine structure (EXAFS), magnetic and magneto-transport including Hall effects studies on the samples indicate the observed ferromagnetism is intrinsic rather than from the secondary impurity phases. (c) 2007 Elsevier Ltd. All rights reserved.
Resumo:
Nanocrystalline Zn0.95 - xNi0.05AlxO (x = 0.01, 0.02, 0.05 and 0.10) diluted magnetic semiconductors have been synthesized by an auto-combustion method. X-ray diffraction measurements indicate that all Al-doped Zn0.95Ni0.05O samples have the pure wurtzite structure. Transmission electron microscope analyses show that the as-synthesized powders are of the size 40 - 45 nm. High-resolution transmission electron microscope, energy dispersive spectrometer and X-ray photoemission spectroscope analyses indicate that Ni2+ and Al3+ uniformly substitute Zn2+ in the wurtzite structure without forming any secondary phases. The Al doping concentration dependences of cell parameters (a and c), resistance and the ratio of green emission to UV emission have the similar trends. (c) 2007 Elsevier B.V. All rights reserved.