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91.
夏继宏 《原子与分子物理学报》2013,30(6)
本文利用分子动力学模拟方法, 研究了液态Ti75Al25合金在不同冷却条件下形成晶体及非晶的过程(Q1:1.0×1013 Ks-1, Q2: 1.0×1011 Ks-1). 利用平均原子体积、双体分布函数、键角分布函数、键对分析和Voronoi多面体方法研究了微观局域结构随温度的变化关系. 研究发现:在Q1冷却过程中,液态Ti75Al25合金在1000 K发生玻璃化转变,形成非晶结构; 而在Q2冷却过程中,液态Ti75Al25合金发生结晶,并最终形成hcp晶体结构。 相似文献
92.
张加宏 《原子与分子物理学报》2013,30(1)
基于密度泛函理论体系下的广义梯度近似(GGA),利用第一性原理方法研究了BaHf0.5Ti0.5O3的电子结构和光学性质.计算结果表明,BaHf0.5Ti0.5O3是一种间隙的半导体材料,其导带底主要由Ba、Hf和Ti的d态电子构成,价带顶则主要由O的p态、Hf 和Ti的d态电子构成;理论计算的介电函数最高峰的峰位与实验结果吻合较好,相对误差小于4%;吸收系数最大峰值为2.43×105cm-1,且吸收主要集中在低能区,静态折射率为2.01,能量损失峰出现在13.24eV处.研究结果为BaHf0.5Ti0.5O3光电材料设计与应用提供了理论依据. 相似文献
93.
HighEnergyHe~+IonImplantationinTitaniumDopedSapphireCrystal¥LIUJianhua;ZHANGQiang;DENGPeizhen;GANFuxi(ShanghaiInstituteofOpti?.. 相似文献
94.
Chen I.-H. Chu S.-W. Sun C.-K. Cheng P.-C. Lin B.-L. 《Optical and Quantum Electronics》2002,34(12):1251-1266
Molecular excitation by the simultaneous absorption of two photons provides intrinsic three-dimensional resolution in laser scanning fluorescence microscopy. Thus induced two-photon absorption and the accompanied multi-photon absorption/ionization not only cause photo-bleaching but also cell damage in the vicinity of the focal point. In this paper, we study the wavelength dependent cell damage induced by high intensity femtosecond near infrared lasers. The study was performed with a Ti:sapphire laser and a Cr:forsterite laser. With a longer output wavelength from a Cr:forsterite laser, multi-photon absorption and auto-fluorescence were found to be significantly suppressed and the destructive plasma formation was found to be greatly reduced. Sustained multi-photon spectra can be observed in most plant specimens with a tightly focused Cr:forsterite laser beam under long term irradiation with more than 100 mW laser average power. In contrast, multi-photon absorption induced destructive plasma formation were frequently observed with a tightly focused Ti:sapphire laser beam within seconds with more than 10 mW laser average power. 相似文献
95.
Gui Sheng DENG Ming Yi LIAO Xue TIAN Jian Bo WANG Key Laboratory of Bioorganic Chemistry Molecular Engineering of Ministry of Education College of Chemistry Peking University Beijing 《中国化学快报》2005,(5)
The nucleophilic addition to α, β-unsaturated carbonyl compounds is a fundamental C-C bond forming reaction in organic chemistry1. Since there are two reaction sites in the α, β–unsaturated carbonyl group, the regioselectivity of the nucleophilic addition (1, 2 vs. 1, 4 addition) is of primary importance when applying this type of reaction in organic synthesis. Factors that control the regioselectivity include the softness and hardness of the attacking nucleophiles2, solvent and temperatu… 相似文献
96.
Hai Ming Yu Liu Hui Nie Baorui Ren Jianping Xie Jingren Qian 《Chinese Journal of Lasers》1993,2(5):393-397
Amplification of spontaneous emission(ASE) in 4m Nd~(3 )-doped fiber pumped by Ti : Al~2O_3 tunable laser is studied theoretically and experimentally. The output of 2.64mW from ASE source pumped at 833 nm is obtained and the experimental results of ASE source are compared with that of Nd~(3 )-doped fiber ring laser. 相似文献
97.
Surface excitations are important in surface sensitive electron spectroscopes, especially in elastic peak electron spectroscopy (EPES) since they may distort quantitative information. This phenomenon is more pronounced at low electron energy and glancing emission angles and should be appropriately corrected.In the present work we investigate quantitatively the role of contaminations, density and surface excitations on electron inelastic mean free paths (IMFPs) in Ti determined by elastic peak electron spectroscopy (EPES) using Cu standard. In the Monte Carlo algorithm the new NIST 3.1 database of electron elastic scattering cross sections was applied. It has been also shown that accounting for surface excitations, as well as for appropriate input parameters (surface composition, density, hydrogen) in the EPES method, is important for accuracy of evaluated IMFPs. Due to high reactivity of Ti, the IMFPs for contaminated Ti may be of interest. The authors indicate the magnitude of various corrections on the IMFPs derived by EPES. 相似文献
98.
直流磁控溅射沉积含He钛膜的研究 总被引:1,自引:0,他引:1
研究了用He/Ar混合溅射气体的直流磁控溅射制备钛膜中,He的掺入现象.分析结果表明,大量的He原子(He/Ti原子比高达56%)被均匀地引入到Ti膜中,其He含量可由混合溅射气体的He分量精确控制.通过调节溅射参数,可实现样品中He的低损伤引入.研究还发现,溅射沉积的含氦Ti膜具有较高的He成泡剂量和高的固He能力,这可能是溅射沉积形成了纳米晶Ti膜所致.纳米晶Ti膜较粗晶材料具有很高浓度的He捕陷中心,使He泡密度增大而泡尺寸减小.随He引入量的增加,Ti膜的晶粒尺寸减小,He引起的晶体点阵参数和X射线衍射峰宽度增大,晶体的无序程度增加.Helium trapping in the Ti films deposited by DC magnetron sputtering with a He/Ar mixture was studied. He atoms with a surprisingly high concentration (He/Ti atomic ratio is as high as 56%)incorporate evenly in deposited film. The trapped amount of He can be controlled by the helium partial amount. The introduction of the helium with no extra damage(or very low damage) can be realized by choosing suitable deposition conditions. It was also found that because of the formation of nanophase Ti film a relative high He flux for bubble formation is needed and the amount of the retain He in sputtering Ti films is much higher than that in the coarse grain Ti films. The nanophase Ti film can accommodate larger concentration of trapped sites to He, which results in a high density and small size of the He bubbles. With the increasing He irradiation flux, the grain size of Ti film decreases and the lattice spacing and width of the X ray diffraction peak increase due to the He introduction, and the film tends to amorphous phase. 相似文献
99.
A platium film was formed on a Ti(Pt-Ti) and on a TiO2(Pt-TiO2-Ti) substrate by the conventional electroplating method (ELP) and by the electroless plating technique (ELSP). The effective minimum film thickness was found to be 0.5 μm judging from the maximum electrocatalytic capablity in alkaline (1 M NaOH) water electrolysis. The film obtained from ELP is superior to that obtained from ELSP, being more tightly bound to the substrate, showing better coverage of the subsrate surface, and also being mechanically stronger. Comparisons with bright Pt and with Pt-black electrodes were made and it is concluded that the electrodes newly prepared using ELP will work as well as Pt-black electrods. The electrodes from ELSP are useful only as cathodes, and are not suitable as anodes. 相似文献
100.
报道了脉冲钛宝石激光器的双波长可调谐运转,双汉总能量达到41.8mJ,调谐范围大于100nm并且研究了双波长运转时的竞争效应,增益损耗的影响,时域特性等。 相似文献