阳极氧化与超临界干燥结合制备多孔硅

多孔硅（PS）在室温下发射强可见光，这一发现在国际上引起极大关注，成为材料科学、半导体物理和化学以及信息科学领域研究的热点［1，2］．最近三、四年，国内外对PS制备工艺、影响PS发光的因素、PS发光机制、PS应用前景等方面进行了广泛的研究［2］，但有一些基本问题仍待解决，如关于PS发光机制尚存在分歧；PS电致发光效率低，离应用差距甚远；高多孔度PS微孔结构不稳定等．PS微孔内溶剂蒸发过程中，由于毛细管张力的存在，造成微孔骨架受力不匀．强的应力使PS骨架脆弱，甚至微孔结构坍缩，从而导致PS结构不稳定．对于高多孔度…     

铜在ρ-Si上激光诱导电沉积过程的研究

由于在微电子器件制造，成像系统及太阳能电池等领域里具有广阔的应用前景，激光诱导化学及电化学沉积金属的研究，最近几年引起了极大兴趣［1－3］，例如Zahavi［4］报道了Pd，Au，Ni－Pd在氩离子激光作用下可以不加偏压实现在半导体Si，InPGaAs上的无掩膜选择性沉积，金属沉积只发生在光照部位．大多数研究工作是围绕应用技术而开展的，理论研究，尤其是光电化学方面的研究尚十分欠缺．我们认为对于普通电镀液中的激光诱导电沉积来讲，既使不需外加偏压，沉积过程也必然伴随着溶液中金属离子与半导体能带之间的电荷传递，因此可以通…     

不同代硝基芳基苄醚树枝配体轴向取代硅(Ⅳ)酞菁光物理性质的比较

在二氯硅酞菁轴向位置引入硝基芳基苄醚树枝配体是一种减少酞菁配合物聚集体形成,提高其光动力活性的有效方法。本文采用UV/Vis、稳态和瞬态荧光光谱法比较了1-3代硝基芳基苄醚树枝配体轴向取代硅(Ⅳ)酞菁的光物理性质。研究结果表明,随着轴向树枝配体代数的增加,Q带最大吸收峰强度增大,酞菁核荧光强度增强,荧光量子产率降低,荧光寿命增长。研究结果将为开发轴向取代硅(Ⅳ)酞菁配合物作为新型光敏剂提供重要的理论依据。     

以RF/SiO2复合气凝胶为前驱体制备介孔α-SiC

以间苯二酚(R)和甲醛(F)为碳源,3-氨丙基三乙氧基硅烷为硅源,无水乙醇为溶剂,利用简捷的一步溶胶-凝胶法和超临界干燥工艺制备RF/SiO2复合气凝胶。RF/SiO2复合气凝胶经碳热还原、煅烧、酸洗等一系列工艺制备出介孔碳化硅(SiC),采用XRD、FTIR、NMR、SEM、TEM和氮气吸附-脱附等分析手段对制备的介孔SiC进行了表征。结果表明,介孔SiC材料为纯的α-SiC,平均晶粒大小为15 nm,BET比表面积为106 m2·g-1,孔径主要分布在21.7 nm和61 nm附近,SiC纳米颗粒大小和分布均匀。     

Electronic structure and thermochemical properties of silicon-doped lithium clusters Li(n)Si0/+, n = 1-8: new insights on their stability

A theoretical investigation on small silicon-doped lithium clusters Li(n)Si with n = 1-8, in both neutral and cationic states is performed using the high accuracy CCSD(T)/complete basis set (CBS) method. Location of the global minima is carried out using a stochastic search method and the growth pattern of the clusters emerges as follows: (i) the species Li(n)Si with n ≤ 6 are formed by directly binding one Li to a Si of the smaller cluster Li(n-1)Si, (ii) the structures tend to have an as high as possible symmetry and to maximize the coordination number of silicon. The first three-dimensional global minimum is found for Li(4)Si, and (iii) for Li(7)Si and Li(8)Si, the global minima are formed by capping Li atoms on triangular faces of Li(6)Si (O(h)). A maximum coordination number of silicon is found to be 6 for the global minima, and structures with higher coordination of silicon exist but are less stable. Heats of formation at 0 K (Δ(f)H(0)) and 298 K (Δ(f)H(298)), average binding energies (E(b)), adiabatic (AIE) and vertical (VIE) ionization energies, dissociation energies (D(e)), and second-order difference in total energy (Δ(2)E) of the clusters in both neutral and cationic states are calculated from the CCSD(T)/CBS energies and used to evaluate the relative stability of clusters. The species Li(4)Si, Li(6)Si, and Li(5)Si(+) are the more stable systems with large HOMO-LUMO gaps, E(b), and Δ(2)E. Their enhanced stability can be rationalized using a modified phenomenological shell model, which includes the effects of additional factors such as geometrical symmetry and coordination number of the dopant. The new model is subsequently applied with consistency to other impure clusters Li(n)X with X = B, Al, C, Si, Ge, and Sn.     

Rechargeable lithiated silicon-sulfur (SLS) battery prototypes

Amorphous columnar structured silicon film electrodes were prepared and electrochemically tested in dioxolane based electrolyte solution, containing LiNO₃. The electrochemical performance of prelithiated amorphous silicon anodes coupled with sulfur composite cathodes was evaluated in full Si-Li-Sulfur (SLS) cells. The reversible capacity at the first 10 cycles was 600 mAh/g sulfur with gradual fading to ~ 380 mAh/g sulfur after 60 cycles which is the highest obtained capacity reported for SLS full cells. Possible reasons for this capacity fading are discussed.     

Folding of alternating dialkylsilylene-spaced donor-acceptor copolymers: the oligomer approach

A series of oligmers with donor-acceptor pairs separated by diisopropylsilylene (iPr(2)Si) spacers, composed of monomer 4b, dimer 5, trimer 6, and tetramer 7, were synthesized to scrutinize the folding behavior. Monomer 4a with a dimethylsilylene (Me(2)Si) spacer was also prepared for comparison. The 4-aminostyrene moiety was used as the donor and the stilbene moiety as the acceptor. Both steady-state and time-resolved fluorescence spectroscopic measurement were made. Regardless of the substituents on the silicon atom, the emission spectra of 4a and 4b exhibit both local excited (LE) emission of the acceptor chromophore and emission from the charge-separated state (CT emission), which are similar to that of the corresponding Me(2)Si-spaced copolymer 2a with the same donor and acceptor chromophores, but different from that of the copolymer with the iPr(2)Si spacer 2b. Dimer 5 behaves like 4 and 2a. As the chain length of the oligomers increases, the emission properties of the higher homologues become prone to that of 2b. Thus, tetramer 7 exhibits emission from the charge-transfer complex, which is essentially same as that of 2b. Moreover, charge-transfer absorptions emerge in 6 and 7. These results suggest that the folding nature of oligomers approaches that of the corresponding polymer, as the degree of oligomerization increases, and the electronic interactions between adjacent donor-acceptor pairs are controlled by the steric effect of the substituents on the silicon atoms and concomitant amplification of the stabilizing energy by extending the distance of the folding structure.     

硅钼杂多阴离子薄膜修饰电极的研究和应用——线性扫描伏安法测定水中可溶性硅酸盐

本文研究了以玻碳电极为基体的1:12硅钼杂多酸根(SiMo_(12)O_(40)~(4-)简称12-MSA)修饰电极的制备及其电化学行为,将12-MSA电极应用于线性扫描伏安法测定天然水中可溶性硅酸盐,结果满意.硅浓度在8.0×10~(-7)～1.7×10~(-3)mol/L,相对标准偏差(n=7)为1.85％,加标回收率为98.2％～103.6％,SiMo_(12)电极具有优良的选择性和稳定性。     

石墨炉原子吸收法直接测定高温合金中硅

研究了混合基体改进剂，灰北、原子化温度以及共存元素的干扰，采用镧和钙作混合基体改进剂后，硅的灵敏度提高，抗干扰能力增强，可以用石墨炉原子吸收直接测定高温合多中硅。方法特征量为０．２ｎｇ，检出限为２．３μｇ／ｇ，对于含硅量为４００μｇ／ｇ左右的合金样品，相对标准偏差为５％左右，回收率在９０％－１１０％之间。     

XRF分析铁矿粉的标准选择判据研究和应用

本文对ＸＲＦ法分析铁矿的基体校正元素进行了研究，并建立了标准选择判据，编制的计算软件可以自动地从大量标样中选择适合该样品分析的标准。该法可用于粉末压片制样的分析，方法快速，准确度和精密度均符合生产要求。