GaN氢化物气相外延生长系统的设计与制作

根据GaN氢化物气相外延生长(HVPE)的原理,设计制作了双温区卧式HVPE系统．根据实际生长中出现的问题和CaN样品的测试情况,对系统进行了逐步的调试和改进．     

Diisobutylaluminium hydride (DIBAL-H) as a molecular scalpel: a new mechanistic proposal for a spiroketal rearrangement

Taking advantage of our knowledge of the capacity of DIBAL-H to de-O-alkylate, we propose an alternative mechanism for a spiroketal rearrangement described by E. Suàrez. We also show that this proposal can account for the formation of the secondary product, whose original structure we propose to correct.     

Phase modulation in dipolar-coupled A2 spin systems: effect of maximum state mixing in H NMR in vivo

Coupling constants of nuclear spin systems can be determined from phase modulation of multiplet resonances. Strongly coupled systems such as citrate in prostatic tissue exhibit a more complex modulation than AX connectivities, because of substantial mixing of quantum states. An extreme limit is the coupling of n isochronous spins (A_n system). It is observable only for directly connected spins like the methylene protons of creatine and phosphocreatine which experience residual dipolar coupling in intact muscle tissue in vivo. We will demonstrate that phase modulation of this “pseudo-strong” system is quite simple compared to those of AB systems. Theory predicts that the spin-echo experiment yields conditions as in the case of weak interactions, in particular, the phase modulation depends linearly on the line splitting and the echo time.     

Thermal treatment on composite γ-zirconium phosphate-silica

The prepared amorphous γ-ZrP\SiO₂ composite had a complicated composition, since a part of γ-ZrP is converted to α-form during the exfoliation of it. The γ-ZrP\SiO₂ composite have specific surface area of 421 m²g^–1. The acidic P–OH groups of the lamellae species placed on the surface (it is ≈1.0 meq g^–1), do not destroy until the temperature of 1030 K. During the thermal treatment the total mass loss of 7.79% was found. This value corresponds to 0.42 mole of H₂O per molecule unit. The water loss process was found very slow, because of the placing of bilamellar species in the composite.     

Wavelength dependence in photochemical vapor deposition of aluminum film using dimethylaluminum hydride

In photochemical vapor deposition of aluminum film on silicon using dimethylaluminum hydride, (CH₃)₂AlH, a surface reaction dominated below a (CH₃)₂AlH pressure of 0.3 m Torr at 200°C, which was induced only with the 160 nm band emitted from a deuterium lamp. A gas-phase reaction occurred above 0.3 mTorr at 200°C, which could be induced by both 160 nm and 240 nm emission bands from the lamp. To distinguish between surface ad gas-phase reactions, a thickness profile was used. At 240°C the surface reaction could be induced even by the 240 nm band, while the deposits formed under illumination of the two bands were thinner than those obtained with only the 240 nm band, indicating occurrence of vacuum ultraviolet (VUV)-enhanced desorption. The mechanism responsible for the observed wavelength dependence in unclear. The electrical resistivity of the films deposited at 200°C was 4.5 μΩ cm, which did not change with wavelength.     

Matrix effects in the determination of butyltin compounds in environmental samples by GC AA after hydride generation

Experiments for the determination of mono-, di and tri-butyltin (MBT, DBT and TBT) by hydride generation/gas chromatography/atomic absorption spectrometry in various matrices (sediment, suspended matter, mussel, algae and water) have revealed that poor butyltin recoveries are obtained in sediments displaying high sulphur and hydrocarbon contents; very poor recoveries were also observed for TBT in sediments with high chlorophyll pigment contents as well as in algal samples. It was however not clear whether the hydride generatin was inhibited by these infering compounds, as was previously assumed in the case of hydrocarbons, or whether interferences affected the atomization rate. Further studies were performed to solve this problem in order to validate this method in the case of analyses of, for example, oil-contaminated sediment and algae. This paper presents the results obtained. It is concluded here that the poor recoveries were due to an inhibition of hydride generation rather than to interference at the atomization stage.     

Nanometric Antimony Powder Synthesis by Activated Alkaline Hydride Reduction of Antimony Pentachloride

A novel chemical reduction method using an activated alkaline hydride (LiH or NaH-t-BuONa) in tetrahydrofuran solvent has been applied to antimony salt reduction. X-ray diffraction and transmission electron microscopy studies have been carried out to characterize the morphology and structure of the materials. Alkali hydride nature influence has been proved. In both cases the process allows to prepare antimony particles in nanometer range from few nanometers to about 20nm which could be used as anodic materials for lithium–ion batteries. With lithium hydride well-crystallized particles inclined to agglomeration were observed whereas finely dispersed amorphous particles were pointing out after activated sodium hydride reduction.     

高压下氢化锂晶体中的离子间力与结合能公式的原子分子设计

本文提出一种利用材料Hugoniot数据研究高压下离子晶体中微观离子状态及其离子间排斥作用势的新方法。对氢化锂晶体进行研究时,我们得到Li~+和H~-离子之间排斥作用势函数,结果表明文献〔1〕中提出的离子压缩效应具有客观性。     

若干具有[(PO4)2Mo5O15]簇骼的化合物的光谱研究

本文对所合成的具有 [(PO4 ) 2 Mo5O1 5]簇骼的 3种新颖的有机 磷钼酸盐簇合物(NH3CH2 CH2 NH3) 2 5[(PO4 ) (HPO4 )Mo5O1 5]·7 5H2 O (Ⅰ ) ,(H3NCH2 CH2 NH3) 3·[(PO4 ) 2 Mo5O1 5]·3H2 O (Ⅱ )和(H3NCH2 CH2 NH3) 2 ·[Cu(en) ][(PO4 ) 2 Mo5O1 5]·5H2 O (Ⅲ )用FTIR ,NIR Raman ,紫外 可见漫反射光谱 (UV VisDRS)和荧光光谱等研究手段 ,对其进行光谱研究 ,探讨其结构和性能的关系。在这些化合物中 ,化合物Ⅰ和Ⅱ具有孤立的 [(PO4 ) 2 Mo5O1 5]簇骼基元 ,而化合物Ⅲ的 [(PO4 ) 2 Mo5O1 5]簇骼基元是由 [Cuen]基团桥联成链 ;磷钼酸盐的特征振动频率和这些化合物的结构相关 ;UV VisDRS显示 ,在 2 0 0和 2 6 0nm左右有两个杂多化合物的特征吸收谱带 ;化合物的稳态荧光光谱中 ,观察到以 2 4 0nm激发 ,在大约 4 0 0nm附近出现的由金属氧簇Oμ→Mo跃迁激发所引起的较强的发射峰 ,在化合物 (Ⅲ )中 ,还观察到通过 [Cuen]的荷移跃迁的以 5 70nm激发所产生的 6 0 4nm的发射峰。     

Structures and syntheses of layered and framework amine-bearing uranyl phosphate and uranyl arsenates

Two hydrated uranyl arsenates and a uranyl phosphate were synthesized by hydrothermal methods in the presence of amine structure-directing agents and their structures determined: (N₂C₆H₁₄)[(UO₂)(AsO₄)]₂(H₂O)₃, DabcoUAs, {NH(C₂H₅)₃}[(UO₂)₂(AsO₄)(AsO₃OH)], TriethUAs, and (N₂C₄H₁₂)(UO₂)[(UO₂)(PO₄)]₄(H₂O)₂, PiperUP. Intensity data were collected at room temperature using MoKα X-radiation and a CCD-based area detector. The crystal structures were refined by full-matrix least-squares techniques on the basis of F² to agreement indices (DabcoUAs, TriethUAs, PiperUP) wR₂=5.6%, 8.3%, 7.2% for all data, and R₁=2.9%, 3.3%, 4.0%, calculated for 1777, 5822, 9119 unique observed reflections (|F_o|?4σ_F), respectively. DabcoUAs is monoclinic, space group C2/m, Z=2, a=18.581(1), b=7.1897(4), c=7.1909(4) Å, β=102.886(1)°, V=936.43(9) Å³, D_calc=3.50 g/cm³. TriethUAs is monoclinic, space group P2₁/n, Z=4, a=9.6359(4), b=18.4678(7), c=10.0708(4) Å, β=92.282(1)°, V=1790.7(1) Å³, D_calc=3.41 g/cm³. PiperUP is monoclinic, space group Pn, Z=2, a=9.3278(4), b=15.5529(7), c=9.6474(5) Å, β=93.266(1)°, V=1397.3(1) Å³, D_calc=4.41 g/cm³. The structure of DabcoUAs contains the autunite-type sheet formed by the sharing of vertices between uranyl square bipyramids and arsenate tetrahedra. The triethylenediammonium cations are located in the interlayer along with two H₂O groups and are disordered. Both TriethUAs and PiperUP contain sheets formed of uranyl pentagonal bipyramids and tetrahedra (arsenate and phosphate, respectively) with the uranophane sheet-anion topology. In TriethUAs, triethlyammonium cations are located in the interlayer. In PiperUP, the sheets are connected by a uranyl pentagonal bipyramid that shares corners with phosphate tetrahedra of adjacent sheets, resulting in a framework with piperazinium cations and H₂O groups in the cavities of the structure.