电流密度对铝合金微弧氧化膜物理化学特性的影响

利用微弧氧化(MAO)技术，在LYl2铝合金上沉积了显微硬度达42.14GPa的超硬陶瓷膜.采用x射线衍射仪和显微硬度计研究了阳极电流密度j_a和阴极、阳极电流密度比j_c/j_a对MAO膜相构成和力学特性的影响.此外，利用扫描电子显微镜和恒电位仪分别对膜的微结构和抗点腐蚀特性进行了分析.结果表明，高j_a制备的膜主要含α-Al₂O₃相，低j_a制备的膜主要含γ-Al₂O₃相.显微硬度测试表明，这类膜有较高的硬度，但以j_a=15A/dm²和j_c/j_a=0.7制备的陶瓷膜硬度最高.抗点腐蚀测试表明，j_c/j_a对陶瓷膜的微结构有很强的影响. 关键词： 微弧氧化 显微硬度 电流密度 抗点腐蚀     

GaAs颗粒镶嵌薄膜的非线性光学性质研究

采用单光束的Z扫描技术研究了GaAs颗粒镶嵌薄膜的非线性光吸收和非线性光折射特性,获得了增强的三阶光学非线性响应.实验测得的非线性折射率系数为 10^-3esu和非线性光吸收系数为10^-1cm/W量级.研究了产生饱和吸收时的光跃迁选择定则,观察到了饱和吸收现象和双激子态的双光子吸收现象,实现其饱和吸收和双光子吸收所需的辐射光强小于10⁴w/cm²结果表明:增强主要起源于量子限域效应,在强限域条件下,库仑作用效应被更强的限域作用所掩盖.GaAs颗粒表现出类似于二能级系统的光学非线性响应特征.     

基于金属离子交换的有机金属凝胶用于检测抗生素与硝基芳香族化合物

废水中有机化合物的快速检测一直是一个重要的问题。采用离子交换法制备了具有荧光特性的铽基金属有机凝胶MOG（Tb）。研究表明,即使存在其他有机化合物,微量的呋喃唑酮（FZD）、甲硝唑（MDZ）、2,4-二硝基甲苯（2,4-DNT）和4-硝基苯酚（4-NP）也能有效猝灭MOG（Tb）的荧光发射,证明MOG（Tb）干凝胶作为一种化学传感器可以有效检测抗生素（FZD、MDZ）和硝基芳香族化合物（2,4-DNT、4-NP）。有趣的是,青霉素钾（PCLP）却能增强MOG（Tb）的荧光。此外,还进行了MOG（Tb）干凝胶的可回收性和水稳定性试验,并得到了较为满意的结果。     

Friedländer approach for the incorporation of 6-bromoquinoline into novel chelating ligands

Nitration of 3-bromobenzaldehyde followed by sodium dithionite reduction provides 5-bromo-2-aminobenzaldehyde, which undergoes the Friedl?nder condensation with a variety of enolizable ketones to afford bidentate and tridentate 6-bromoquinoline derivatives. These species may be dimerized with Ni(0) to form biquinolines or treated under Sonogashira conditions to afford 6-alkynyl derivatives. Examination of optical properties indicate an unusually high emission quantum yield for 6,6'-biquinolines. [structure: see text]     

Design of the IMP microbeam irradiation system for 100 MeV/u heavy ions

A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to pre-selected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simultaneously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C^6＋ ion beam to 1 μm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced.     

Scaling of the hysteresis in the glass transition of glycerol with the temperature scanning rate

By measuring the dependences of the temperature-dependent primary ("alpha") dielectric relaxation time behavior on the temperature scanning rate for the glass-forming glycerol, we study the scaling of hysteresis at the glass transition in glycerol. Based on the Vogel-Fulcher-Tammann (VFT) expression and the Angell's fragility concept, notable correlations of the systematic kinetic fragility, and of the hysteresis effect in the vitrification∕fusion "alpha"-relaxation process of glycerol, with the temperature scanning rate, were reasonably analyzed and discussed. It was observed that the kinetic fragility m and the apparent glass-transition temperature hysteresis width ΔT(g)(a), respectively, scaled the temperature scanning rate q as m ≈ α(m)q(-γ) and ΔT(g)(a) ≈ A(0) + αq(β), at which the exponents, γ and β, were suggested to be characteristic of the resistance to the structure change or fragility change of the system during the glass transition. The observed scaling laws are quite similar to the scaling power law for the thermal hysteresis in the first-order phase transition (FOPT) of solids, providing a significant insight into the hysteresis effect in the glass transition of the glass-forming liquids.     

Deposition of ZnO Films on Freestanding CVD Thick Diamond Films

For ZnO/diamond structured surface acoustic wave （SAW） filters, performance is sensitively dependent on the quality of the ZnO films. In this paper, we prepare highly-oriented and fine grained polycrystalline ZnO thin films with excellent surface smoothness on the smooth nucleation surfaces of freestanding CVD diamond films by metal organic chemical vapour deposition （MOCVD）. The properties of the ZnO films are characterized by x-ray diffraction （XRD）, scanning electron microscopy （SEM）, and photoluminescence （PL） spectrum. The influences of the deposition conditions on the quality of ZnO films are discussed briefly. ZnO/freestanding thick-diamond-film layered SAW devices with high response frequencies are expected to be developed.     

Bare-State Time-Evolving Operator Solution to Raman Model in A Configuration

We derive exact analytical expressions of time-evolving bare-state operators of level occupation numbers and the photon numbers for a composite system consisting of a three-level atom interacting with two modes ofa quantized electromagnetic field in A configuration. These results demonstrate the oscillations with three-family frequencies for a nonzero detuning, which dramatically differ from the previous results showing only single-family Rabi oscillations.     

阴极电压脉冲占空比对钛合金微弧氧化膜特性的影响

利用自制多功能微弧氧化电源,在保持双极性电压脉冲幅度不变的条件下,研究了阴极电压脉冲占空比（d_c）对钛合金微弧氧化膜特性的影响.结果表明：阴、阳极的峰值电流随处理时间的变化分为几个不同阶段,各阶段的开始和结束时间与d_c密切相关.氧化膜主要由金红石和锐钛矿相TiO₂组成,金红石相TiO₂的相对含量在d_c=50%附近随d_c的 关键词： 微弧氧化 钛合金 占空比