ZrB2质与TiB2质耐火材料

介绍了ZrB2 与TiB2 以及其他一些非氧化物高温材料的性质 ;ZrB2 与TiB2 在高温工业中的应用与预期发展 ;ZrB2 与TiB2 原料与制品的生产 ,包括自蔓延高温合成ZrB2 与TiB2 ;ZrB2 质与TiB2 质复合材料 ,如ZrB2 -SiC ,TiB2-SiC ,ZrB2 -BN ,TiB2 -BN ,ZrB2 -MoSi2 ,TiB2 -MoSi2 ,ZrB2-C ,TiB2 -C ,ZrB2 -B4C ,TiB2 -B4C等。     

Electronic Structure and Properties of the O2+2, SO2+ and S2+2 Diatomic Dications

Multiply charged ions show novel energetic features which can potentially have useful photophysical properties. In order to investigate these interesting type systems, energy interaction curves for the ground and excited electronic states of O²⁺₂, SO²⁺, and S²⁺₂ have been generated by the ab initio complete active space multiconfiguration self-consistent field (CAS-MCSCF) method. The calculations were carried out in a triple-zeta sp plus double-zeta d Gaussian function basis set using compact effective potentials to replace the core electrons. In order to gauge the accuracy of the results, analogous calculations were carried out on the valence isoelectronic N₂ and NO⁺ systems for which experimental information is available for comparison of geometric and spectroscopic properties. Diverse high energy spectroscopy experiments on O²⁺₂ are interpreted and reconciled using the calculated ground and excited state energy interaction curves. Special attention is paid to the ₃Σ₊^u state, whose location and character have been particularly puzzling. Almost all the dication molecular states studied show the characteristic avoided crossing of diabatic states which gives a trapped equilibrium structure and a barrier to dissociation. These features make the dication kinetically stable, but thermodynamically unstable with an exothermic dissociation energy. The spectroscopy experiments on O²⁺₂ show that these states are experimentally attainable.     

沉淀法白炭黑与纳米级二氧化硅

依据二氧化硅粒子的形成过程，指出传统沉淀法白炭黑并不具有科学意义上的纳米实质，研究重点侧重于改进其分散性能，同时也简介了纳米二氧化硅的制备方法及用途。     

Eu~(2+)掺杂SrSi_2O_2N_2和Sr_(0.37)Ba_(0.60)Si_2O_2N_2荧光粉的发光性能及应用

采用高温固相法合成Sr_(0.97)Eu_(0.03)Si_2O_2N_2和Sr_(0.37)Ba_(0.60)Eu_(0.03)Si_2O_2N_2荧光粉,通过X射线衍射、激发光谱、发射光谱及转换后LED器件的性能等研究了荧光粉的结构、发光性能和稳定性。结果表明:在稀土Eu2+掺杂的Sr Si2O2N2荧光粉中,当部分Sr2+被Ba2+取代后,形成三斜晶系的Sr_(0.37)Ba_(0.60)Eu_(0.03)Si_2O_2N_2荧光粉,激发和发射光谱红移,在近紫外-蓝光区具有更高的激发效率。将2种荧光粉与Ga(N)In芯片封装,Sr0.37Ba0.60Eu0.03Si2O2N2荧光粉转换的白光LED器件,在光效、显色指数和光效维持特性方面均高于Sr_(0.97)Eu_(0.03)Si_2O_2N_2转换的LED器件。     

氢氧直接合成法制过氧化氢技术进展

氢气和氧气直接合成过氧化氢是典型的原子经济性反应，因过程简单、产品清洁、生产成本低而成为催化领域研究开发的一个热点。总结了该法近年来在催化剂活性组分的选取及载体方面的进展；详细介绍了溶剂的选取和反应机理；讨论了各种反应器的安全性。指出今后的研究重点是提高氢气利用率、开发新型的反应器、提高过程的安全性。     

多卤代吡啶选择性合成醚类的反应

以KOH为碱,DMSO为溶剂,在空气中,温度为50℃的条件下,多卤代吡啶和苯酚类化合物反应,形成相应的醚类化合物,该反应具有很好的收率以及区域选择性,是一种有效构建C-O键的方法;以K_2CO_3为碱,DMSO和H_2O为溶剂,在空气中,室温下,多卤代吡啶和苯硫酚类化合物反应,形成相应的的吡啶硫醚化合物,该反应也具有很好的收率以及区域选择性,是一种有效构建C-S键的方法。     

生产乙炔对电石的要求及乙炔清净

目前国内外乙炔大部分仍是由电石制得。然而由于工业电石除CaC2 外还含有很多杂质 ,所以生产乙炔不仅要求电石的纯度、粒度 ,还要求水温。一般电石的块度采用 8～ 2 5mm ,发生器温度控制在 85± 5℃ ,乙炔气体中含H2 S、H3 P、NH3 等气体会使氯乙烯合成氯化催化剂活性下降。因此 ,必须对乙炔气体进行清洁。采用次氯酸钠液体的氧化性将乙炔中的杂质氧化成酸性物质而除去。     

纳米TiO2和微米SiO2改性及分散性能的研究

采用不同的分散工艺和改性剂对纳米TiO2和微米SiO2粉体进行处理,使用激光粒度仪、红外光谱(IR)、热失重(TG)等手段对粉体粒径,粉体表面结构进行表征,探讨了超微粉体在乙二醇(EG)中分散的最佳工艺.结果表明:钛酸酯偶联剂(NDZ-201)可在纳米TiO2表面接枝,接枝率约为6%;硅烷偶联剂(KH570)可在微米S...     

铈硅包覆金红石型钛白粉及光催化性研究

采用溶胶-凝胶法,制备了铈硅包覆金红石型钛白粉,通过正交实验考察了浆液浓度、分散剂用量和两种包膜剂含量对铈硅包覆金红石型钛白粉性能的影响。采用Nano-ZS型粒度仪、扫描电镜（SEM）、透射电镜（TEM）和能谱（EDS）等测试手段,对金红石型钛白粉的Zeta电位、表面形貌和元素进行了表征。结果表明：在水浴温度为80 ℃左右、转速为600 r/min、浆液质量浓度为400 g/L、分散剂质量分数为0.1%、二氧化铈质量分数为3%、二氧化硅质量分数为4%的条件下,金红石型钛白粉表面包覆了两层均匀而致密的二氧化硅和二氧化铈膜;罗丹明B光催化降解实验证实,铈硅包覆明显改善了金红石型钛白粉的光催化屏蔽性。     

Separation and purification of aflatoxins B1, B2, G1 and G2, and comparison of semi-synthetic aflatoxins B2 and G2 with naturally-occurring aflatoxins B2 and G2

A method is described for the isolation of highly purified aflatoxins B₁, B₂, G₁ and G₂ from extracts ofAspergillus flavus. The four aflatoxins, isolated from background impurities by rapid passage of the extracts through an acid alumina column, are separated from each other by chromatography on a silica gel column. Aflatoxins B₂ and G₂ are prepared by hydrogenation of the mixture of aflatoxins B₁, B₂, G₁ and G₂ and then separated by elution from a silica gel column with chloroform containing 0.7% ethanol. A comparison of semi-synthetic aflatoxins B₂ and G₂ with naturally-occurring aflatoxins B₂ and G₂ shows no significant difference in physical properties. Presented at the AOCS-AACC Meeting, Washington, D.C. April, 1968.     

PbCl2-ZnCl2-H2O和CaCl2-PbCl2-H2O三元体系373K相平衡

采用等温溶解平衡法研究了两个三元体系PbCl₂-ZnCl₂-H₂O和CaCl₂-PbCl₂-H₂O在373 K时的相平衡,测定了平衡溶液的溶解度和密度,并根据溶解度数据和对应的平衡固相绘制了相图和密度-组成图,根据相图对单变量曲线和结晶区进行了讨论。研究发现,两个三元体系均为简单共饱和型,均无复盐和固溶体生成,有一个共饱点,两条单变量曲线,两个结晶区。平衡液相对应的固相由XRD确定,并对实验结果进行了简要的讨论。     

Al2O3-SiO2-TiO2-ZrO2复合陶瓷膜的制备与表征

采用Sol-Gel法制备出掺杂SiO2,TiO2及ZrO2改性的γ-Al2O3膜,并通过SEM,EPMA,AFM等测试手段对膜结构和性能进行表征.探讨了制膜工艺条件对膜性能及结构的影响.制备的Al2O3复合膜膜厚为1～2μm,结构均匀无缺陷.     

Solubility and microstructural development of TiO2-containing 3Al2O3·2SiO2 and 2Al2O3·SiO2 mullites obtained from single-phase gels

The interdependence of the titanium oxide amount and the anisotropic growth of mullites prepared from single-phase gels were investigated. Gels with stoichiometries 3(Al_2−xTi_xO₃)·2(SiO₂) and 2(Al_2−xTi_xO₃)·(SiO₂), with 0 ≤ x ≤ 0.15 were prepared by the semialkoxide method. Gels and specimens heated at temperatures between 1200 and 1600 °C were characterized by using infrared spectroscopy (IR), X-ray diffraction (XRD) and transmission and field emission scanning electron microscopies (TEM and FESEM). Al₂TiO₅ as minor impurity was detected in both series of mullites for gel precursor compositions x = 0.10 and x = 0.15, obtained at temperatures between 1200 and 1600 °C. Variations of lattice parameters of mullite, processed at temperatures from the range between 1400 and 1600 °C, with the starting nominal amount of titanium oxide indicated that the solubility limit of titanium oxide was in ranges 3.8–4.1 and 4.1–4.4 wt% TiO₂ for 3:2 and 2:1 mullites series, respectively. The anisotropic growth of titanium-doped mullite crystalline grains was significant only when the nominal amount of titanium oxide exceeded the limit of solubility into the mullite structure (for both mullite series). Stronger anisotropy occurred for the 3:2 series specimens, i.e. for the SiO₂-richer mullites. In both series of mullites, the anisotropic grain growth was observed for the process temperatures higher than 1400 °C; the crystalline grains of mullites processed at lower temperatures were equiaxials and of almost the same size.     

Magnetic and bioactive properties of MnO2/Fe2O3 modified Na2O-CaO-P2O5-SiO2 glasses and nanocrystalline glass-ceramics

Glass and in-situ nanocrystalline glass-ceramics of compositions 45SiO₂-25CaO-10Na₂O-5P₂O₅-xFe₂O₃-(15-x) MnO₂ are investigated for their magnetic and in-vitro bioactive properties. The ferrimagnetic character is observed in the high Fe₂O₃ containing in-situ nanocrystalline glass-ceramics. Saturation magnetization and coercivity increases with Fe₂O₃. After soaking in the simulated body fluid (SBF), the powdered as well as the bulk glasses and glass-ceramics are investigated using various characterization techniques. The presence of MnO₂ increases the leaching of Na⁺ ions from the glasses and also attracts the Ca²⁺ cations from the SBF as compared to Fe₂O₃ containing nano-crystalline glass-ceramics. It also increases the tendency to form hydroxyl apatite (HAp) layer. Microwave Plasma Atomic Emission Spectroscopy (MP-AES), Fourier Transform Infrared (FTIR) spectra, X-ray diffraction and Scanning electron micrographs (SEM) after soaking in the SBF confirm the HAp formation on the surface of all the glasses and glass-ceramics. Urbach energy also indicates the structural modifications on the surfaces of the glass and glass-ceramics after soaking in the SBF.     

Al2O3-SiO2-ZrO2-TiO2溶胶的制备与研究复合

以硝酸铝、正硅酸乙酯、氧氯化锆、钛酸丁酯为前驱体，水和无水乙醇为溶剂，用溶胶-凝胶法制备适合涂膜的复合溶胶。     

Enhancement of Curie temperature and photoluminescent properties of Nd2Mo2O7, Ho2Mo2O7, and Gd2Mo2O7

For Nd_1.90Er_0.10Mo₂O₇, Ho_1.90Er_0.10Mo₂O₇, and Gd_1.98Eu_0.02Mo₂O₇ nominal compositions, oxide compounds were prepared by solid-state reaction method. X-ray diffraction measurements show that molybdenum oxides formed cubic phase except for Nd_1.90Er_0.10Mo₂O₇. Scanning electron microscopy was used to observe their microstructure and elemental analysis. The photoluminescence properties of the materials, the excitation and emission spectra and the decay curve, were investigated using photoluminescence spectrophotometer. Dielectric and piezoelectric properties of the ptoluminescent materials, the dielectric constant, dielectric loss, piezoelectric constant, and Curie temperature, were measured for electrical characterization. Nd_1.90Er_0.10Mo₂O₇, Ho_1.90Er_0.10Mo₂O₇, and Gd_1.98Eu_0.02Mo₂O₇ materials show both photoluminescence and piezoelectric properties.     

Structure and microwave dielectric properties of BaAl2−2xLi2xSi2O8-2x ceramics

BaAl_2-2xLi_2xSi₂O_8-2x (x = 0, 0.005, 0.0075, 0.01, 0.02, 0.03) ceramics were synthesized by solid-state sintering method. Based on density functional theory, the first-principle calculations provided by the Cambridge Sequential Total Energy Package (CASTEP) software were introduced to the BaAl₂Si₂O₈ (BAS) system. In an effort to confirm the site occupied by Li⁺, we discussed the formation energy and final energy of different positions of Li⁺ doped BAS. The result demonstrated that Li⁺ should substitute Al³⁺ to promote the hexacelsian-to-celsian transformation with the aid of generated oxygen vacancies. The sintering behavior, crystal structure, surface appearance, and microwave dielectric properties of samples were investigated. Completely transformed celsian could be obtained when x = 0.005–0.03, which lowered the sintering temperature from 1400 °C (x = 0) to 1300 °C (x = 0.03), as well as strikingly improved the compactness, quality factor (Q × f) value and temperature coefficient of resonant frequency (τ_f) of BAS ceramics. When x = 0.1, unveiling the significant effects of Al-position ion substitution, BaAl_1.98Li_0.02Si₂O_7.98 ceramic sintered at 1350 °C for 5 h exhibited a supreme Q × f value of 48,620 GHz, and the ε_r and τ_f values were 6.99 and -23.29 × 10^?6 °C^?1, respectively.