Luminescence enhancement by hydrogenation of Si:Er,O

Erbium (Er)- and oxygen (O)-doped Cz–Si was additionally doped with hydrogen, using plasma enhanced chemical vapour deposition. Photoluminescence (PL) spectra show a large enhancement especially for samples treated with solid phase epitaxy before hydrogenation and annealing at 900°C later. Secondary ion mass spectroscopy measurements give evidence for an enhanced diffusion of O and Er at this temperature towards the surface. Etching shows that the PL does not stem from the heavily doped surface layer but from a deeper region with lower Er concentration. This conclusion is supported by the appearance of the so-called “cubic” centre with low solubility. Comparing the PL yield of the hydrogenated samples to that of samples with similar Er volume concentration but without hydrogenation still gives a large enhancement. We thus conclude that hydrogen can enhance the solubility of the cubic centre in Si:Er,O.     

Metallization of U3O8via catalytic electrochemical reduction with Li2O in LiCl molten salt

The concept of a novel electrochemical reduction process for the treatment of spent nuclear fuels in Li₂O-LiCl molten salt was proposed and fresh tests using U₃O₈ powder were carried out to elucidate the reaction mechanism and verify the feasibility of the process. Electrolysis of Li₂O and reduction of U₃O₈ powder took place simultaneously at the cathode part of the electrolysis cell via a catalytic EC mechanism and the conversion of U₃O₈ to U metal was more than 99%. This revised version was published online in June 2006 with corrections to the Cover Date.     

质子化丙酮分子团簇的结构和振动光谱

用密度泛函B3LYP/ 6 3 1G(d)方法 ,对质子化丙酮分子团簇 (CH3COCH3) nH+ (n =1～ 7)弱相互作用体系进行了全自由度能量梯度优化 ,得到了该系列团簇的稳定结构及其对应的体系能量 .通过对构型的分析得出了质子化丙酮分子团簇 (CH3COCH3) nH+ (n =1～ 7)的生长规律 .计算了中性丙酮分子团簇体系的质子亲合能并总结出其变化趋势 .分析讨论了质子化团簇的红外振动光谱 ,发现质子化团簇的振动光谱普遍较中性环型团簇的振动光谱复杂 ,最强的振动峰来源于质子在溶剂壳中两个氧原子之间的振动 ,而且随着团簇尺寸的增加羰基的伸缩振动峰的数目也随之增多     

Investigation of the Li1+xV3O8 electrode–organic electrolyte interface by scanning photoelectron microscopy

To investigate the formation of a solid electrolyte interface (SEI) on the Li_1+xV₃O₈ electrode surface in the thermodynamic stability range of the organic electrolyte, we applied scanning photoelectron microscopy (SPEM) to a pristine electrode and to an electrode after ten cycles. The F K-edge absorption spectrum of the cycled electrode showed that LiF forms on the electrode surface during the lithium insertion–extraction process in the Li_1+xV₃O₈/Li cell. The photoelectron spectrum for the cycled electrode showed intense spectral features corresponding to Li 1s, F 2s, F 2p, and P 2p electron signals, whereas these spectral features were of negligible intensity for the pristine electrode. The above results give strong support for the formation of an SEI that consists of LiF and compounds containing phosphorus during operation of the battery. The SPEM images also revealed that the fluorine distribution on the surface of the cycled electrode was inhomogeneous.     

Computational analysis of native and modified oligofructosides

This paper presents a quantum chemical calculation of native (2–7 fructoside residues) and chemically modified (2–4 fructoside residues) levan molecule models. A levan modification was carried out by oxidation and the following reduction or hyrdazonation of the fructoside rings. The conformational particularity and reaction ability was studied for the native and for the modified levan molecules.     

Microwave‐improved polymerization of ϵ‐caprolactone initiated by carboxylic acids

The ring‐opening polymerization of ε‐caprolactone (ε‐CL), initiated by carboxylic acids such as benzoic acid and chlorinated acetic acids under microwave irradiation, was investigated; with this method, no metal catalyst was necessary. The product was characterized as poly(ε‐caprolactone) (PCL) by ¹H NMR spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and gel permeation chromatography. The polymerization was significantly improved under microwave irradiation. The weight‐average molecular weight (M_w) of PCL reached 44,800 g/mol, with a polydispersity index [weight‐average molecular weight/number‐average molecular weight (M_w/M_n)] of 1.6, when a mixture of ε‐CL and benzoic acid (25/1 molar ratio) was irradiated at 680 W for 240 min, whereas PCL with M_w = 12,100 and M_w/M_n = 4.2 was obtained from the same mixture by a conventional heating method at 210 °C for 240 min. A degradation of the resultant PCL was observed during microwave polymerization with chlorinated acetic acids as initiators, and this induced a decrease in M_w of PCL. However, the degradation was hindered by benzoic acid at low concentrations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 13–21, 2003     

Layout-Specific Circuit Evaluation in 3-D Integrated Circuits

In this paper, we describe a comprehensive layout methodology for bonded three-dimensional integrated circuits (3D ICs). In bonded 3D integration technology, parts of a circuit are fabricated on different wafers, and then, the wafers are bonded with a glue layer of Cu or polymer based adhesive. Using our layout methodology, designers can layout such 3D circuits with necessary information on inter-wafer via/contact and orientation of each wafer embedded in the layout. We have implemented the layout methodology in 3DMagic. Availability of 3DMagic has led to interesting research with a wide range of layout-specific circuit evaluation, from performance comparison of 2D and 3D circuits to layout-specific reliability analyses in 3D circuits. Using 3DMagic, researchers have designed and simulated an 8-bit encryption processor mapped into 2D and 3D FPGA layouts. Moreover, the layout methodology is an essential element of our ongoing research for the framework of a novel Reliability Computer Aided Design tool, ERNI-3D.     

质子交换铌酸锂波导MMI光功分器

利用三维非旁轴近似光束传输法对退火质子交换铌酸锂渐变折射率分布波导中的自镜像效应进行分析与模拟 .在此基础上 ,利用退火质子交换技术在 X切 Y传铌酸锂衬底上进一步制作了 1× 8MMI光功分器 .测试表明器件实现了 1路分成 8路的光功分功能 .     

LaNiO3薄膜热稳定性的研究

LaNiO3导电金属氧化物薄膜在现代应用科学研究中作为电极和过渡阻挡层倍受青睐，它具有很好的导电特性和稳定性。该文采用射频溅射法制备了具有(100)择优取向的赝立方结构LaNiO3-x薄膜，并进行了原位热处理。实验结果表明，在265℃的处理条件下，LaNiO3薄膜表现出不稳定性，晶格中的氧在2h内失去了2.7％。氧的损失对品格结构没有明显影响，但薄膜的导电性能明显下降，折射率和消光系数也具有相同幅度的下降。对薄膜的应用具有一定的影响。该文从LaNiO3薄膜的导电机理方面对实验现象给出了分析和解释。