U_3Si_2Al弥散型燃料的辐照肿胀研究

介绍了U3Si2 Al弥散型燃料的辐照肿胀机理。将弥散型燃料的芯体视为连续基体中的微型燃料元件 ,应用裂变气体的行为机理描述燃料相中的气泡形成过程。研究结果表明 :燃料相的肿胀引起燃料颗粒和金属基体之间的力学相互作用 ,金属基体能抑制燃料颗粒的辐照肿胀。在一定辐照条件下 。

Ultra High-Speed InP/InGaAs SHBTs with f_t of 210GHz

PolYimide passivation and planarization process techniques for high speed InP/InGaAs single heterojunction bipolar transistors （SHBTS） are developed. A maximum extrapolated ft of 210GHz is achieved for the SHBT with 1.4μm × 15μm emitter area at VCE = 1. 1V and Ic = 33.5mA. This device is suitable for high speed and low power applications,such as ultra high speed mixed signal circuits and optoelectronic communication ICs.

Reaction behavior of ferric oxide in system Fe_2O_3-SiO_2-Al_2O_3 during reductive sintering process

Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe2O3?SiO2?Al2O3 during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe2O3?SiO2?Al2O3, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

Effect of minor Sc and Zr addition on microstructure and properties of ultra-high strength aluminum alloy

The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys （x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%）, produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3（Sc,Zr） particles formed during solidification as heterogeneous nuclei. Secondary Al3（Sc,Zr） precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05%Sc and 0.15%Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.

Synthesis and Crystal Structure of β-Diketiminate Ytterbium Dichloride

The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pna21(#33) with a = 19.657(8), b = 9.581(4), c = 14.107(6) ? V = 2656.8(18) 3, Z = 4, C25H33N2O2Cl2Yb, Mr = 637.49, Dc = 1.594 g/cm3, F(000) = 1268.00 and m(MoKa) = 3.744mm-1. The final R and wR are 0.031 and 0.073 for 2596 observed reflections with I > 2s(I), respectively. The X-ray crystal structure analysis revealed that the center ytterbium(III) is bonded to two chloride anions, two oxygen atoms from two tetrahydrofuran molecules and one chelate ligand b-diketiminate to form a six-coordinate distorted octahedral geometry.

Crystal facet effect induced by different pretreatment of Cu_(2)O nanowire electrode for enhanced electrochemical CO_(2) reduction to C_(2+) products

Electrocatalytic CO_(2) conversion has been considered as a promising way to recycle CO_(2) and produce sustainable fuels and chemicals.However,the efficient and highly selective electrochemical reduction of CO_(2) directly into multi‐carbon(C_(2+))products remains a great challenge.Herein,we synthesized three type catalysts with different morphologies based on Cu_(2)O nanowires,and studied their morphology and crystal facet reconstruction during the pre‐reduction process.Benefiting from abundant exposure of Cu(100)crystal facet,the nanosheet structure derived Cu catalyst showed a high faradaic efficiency(FE)of 67.5%for C_(2+)products.Additionally,electrocatalytic CO_(2) reduction studies were carried out on Cu(100),Cu(110),and Cu(111)single crystal electrodes,which verified that Cu(100)crystal facets are favorable for the C_(2+)products in electrocatalytic CO_(2) reduction.Our work showed that catalysts would reconstruct during the CO_(2) reduction process and the importance in morphology and crystal facet control to obtain desired products.

Influence of chemical modification by Y2O3 on eutectic Si characteristics and tensile properties of A356 alloy

The modification of A356 aluminum-silicon alloy using yttrium oxide (Y2O3) was studied. Addition levels of up to 2.5 wt.% Y2O3 were investigated. A premixed powder of Al-30wt.%Y2O3 was added to the melt at about 750℃ using vortex method. Samples were then poured in sand mold. The results showed that evident modification was obtained using the Y2O3 addition. The optimum level was 1.5 wt.%, and was corresponding to a eutectic temperature depression from 568 to 557℃. The eutectic Si particles were refined in length from 44.8 to 8.3 μm, and modified in aspect ratio from 6.8 to 0.98. Higher additions of Y2O3 caused de-modification of the eutectic Si particles. The ductility of the modified specimens was enhanced by more than 20% compared to the unmodified ones. This was associated with a gradual transfer from cleavage to a more ductile mode of fracture.

Crystal Structure of 4, 5-trans-2-Amino-1, 3, 3-tricyano-4, 5-di (4-chlorophenyl)cyclopentene. Ethanol. Monohydrate

The crystal and molecular structure of 4, 5-trans-2-amino-1, 3, 3-tri-cyano-4, 5-di(4-chlorophenyl) cyclopentene. ethanol - monohydrate has been deter-mined by X-ray diffraction method. The crystal (C20H12N4Cl2. C2H6O. H2O, Mr=443. 33) is triclinic with space group P1, a= 11. 033(4), b= 12. 199(3), c= 10. 732(3) A, a=114. 46(2), β=118. 33(3) γ=81. 56(3), V=1155- 1(7) A3, Z=2, Dc= 1. 275g/cm3, μ(MoKa) = 3. 05cm-1, F(000) = 460, R= 0. 070, Rw = 0. 089 for1965 observed reflections (I>3(I)). The phenyl groups are in equatorial positionsand form dihedral angles of 67. 89 and 63. 77° with the central 5-ring. X-ray analysisreveals that in the five membered ring the C (1) -C (2) bond is longer than normal double C=C bond while the C(2) -N (2) bond is shorter than normal C(sp)2-N bond.

One pot synthesis, crystal structures and properties of two new MOFs with imidazole-containing tripodal ligand

Two new different Cu(Ⅱ) MOFs with the same 1,3,5-tris(1-imidazolyl) benzene(tib) ligand {[Cu(tib)2]·(H2O)2·Br2}n(1) and {[Cu2(tib)·Br·Cl]·2Br}n(2) were obtained by one pot synthesized of tib with CuBr in the presences of HCl and water. X-ray single crystal diffraction analyses indicate that both complexes 1 and 2 have two dimensional frameworks containing different building blocks. Each Cu(Ⅱ) atom in complex 1 is coordinated by four N atoms from different tib ligands. However, there are two different cryptographic Cu(Ⅱ) atoms in complex 2, one is four coordinated by two bromine atoms and two N atoms from different tib ligands, the other is six coordinated by two chloride atoms and four N atoms from different tib ligands. The thermal gravimetric analysis of complexes 1 and 2 are depicted in the paper.

Ionic liquid assisted synthesis of flowerlike Cu_2O micro-nanocrystals

Novel flowerlike Cu20 micro-nanocrystals were prepared by a greener reductive reaction of cupric acetate monohydrate with ethylene glycol in aqueous solutions of [C8mim]X （X = CI-, Br-, BF4-, PFr-） and [C,,mim][BF4] （n = 4, 6, 8）. The obtained mi- crostructures of Cu2O were characterized by Scanning Electron Microscopy （SEM）, X-ray diffraction （XRD） and Fourier Transform Infrared （FT-IR）. The effects of cations, anions and concentration of the ionic liquids on the morphology of Cu20 were examined in some details. The results suggest that the formation of flowerlike Cu20 was governed by a [Csmim][BF4] controlled reductive reaction mechanism. As one of their applications, the Cu20 nanoparticles were used for the photocatalytic degradation of methylene blue in aqueous solution, and high photocatalytic activity was observed.