α—和β—三取代钨硅酸盐异构体的合成及催化性能

本文报道了α－和β－ＫａＨｂＳｉＷ３Ｍ３（ＯＨ２）３Ｏ３７．ＸＨ２Ｏ（Ｍ＝Ｍｎ，Ｃｒ）的合成，表征及其催化丙烯醇环氧化反应的性质，元素分析，红外光谱，ＵＶ光谱，磁化率等数据表明，该杂多阴离子为三取代的Ｋｅｇｇｉｎ结构。     

稀土元素钨钒锗（磷）杂多配合物热稳定性研究

合成了十八种Ｋｅｇｇｉｎ结构稀土元素四元杂多配合物Ｋ１２Ｈ３「Ｌｎ（ＧｅＷ１０ＶＯ３９）２」；ＸＨ２Ｏ和Ｋ１１Ｈ２「Ｌｎ（ＰＷ１０ＶＯ３９）２」．ＸＨ２Ｏ。利用ＴＧ－ＤＴＡ，变温红外光谱，变温Ｘ射线衍射和溶解性实验方法，对配合物的热稳定性进行了研究，讨论了影响热稳定性的因素。     

X射线衍射K值法测定蓝色氧化钨中的WO_3、WO_（2．72）和WO_（2．90）

Ｘ射线衍射Ｋ值法测定蓝色氧化钨中的ＷＯ_３、ＷＯ_（２．７２）和ＷＯ_（２．９０）潘世伟（上海进出口商品检验局２０００ｇ２）蓝色氧化钨又名β－氧化钨（简称蓝钨），化学组分为ＷＯ２．９０，属四方晶系。由于蓝钨具比表面大、掺杂均匀、比ＷＯ３更易被还原、可适?..     

CaO—SiO2—P2O5—H2O系统中CBC材料的溶胶—凝胶过程研究：II.凝胶的…

利用ＸＲＤ，ＩＲ，ＳＥＭ及＾２９Ｓｉ，＾３１Ｐ－ＮＭＲ等测试技术研究了ＣａＯ－ＳｉＯ２－Ｐ２Ｏ５－Ｈ２Ｏ系统中干凝胶在烧成过程中的物相变化及物相间发生的化学反应，认为凝胶在烧成过程的不同阶段发生的主要化学反应如下：（１）６７３～７７３Ｋ，由Ｃａ２Ｐ２Ｏ７和Ｃａ（ＮＯ３）２．４Ｈ２Ｏ反应生成了ＯＨＡｐ；（２）７３３～８７３Ｋ，由Ｃａ２Ｐ２Ｏ７和ＣａＯ反应生成了β－Ｃ３Ｐ；（３）８７３～９７３Ｋ；由Ｃ     

溶胶凝胶法制备K_2O－PbO－B_2O_3－SiO_2系统梯度折射率材料

溶胶凝胶法制备Ｋ＿２Ｏ－ＰｂＯ－Ｂ＿２Ｏ＿３－ＳｉＯ＿２系统梯度折射率材料吕文生，周世（华东理工大学无机材料系２００２３７）杜新民，沈定坤，陈幼新（中国科学院上海硅酸盐研究所２０００５０）ＡＮｅｗＭａｔｅｒｉａｌｗｉｔｈＧｒａｄｉｅｎｔＲｅｆｒａｃｔ...     

三核钼钨簇合物的循环伏安法研究

本文利用循环伏安法在铂电极上研究了三核钼钨簇合物（〔Ｍｏ３Ｌ〕２＋ ,〔Ｗ ３Ｌ〕２＋其中Ｌ＝ 〔（μ３－ Ｏ）２（μ－ ＣＨ３ＣＯＯ）６（Ｈ２Ｏ）３〕的电化学性质及其对电化学性质的影响因素。     

混合钠铝硅玻璃熔融时的粘度

测量了（２５－ｘ）Ｎａ２Ｏ－ｘＫ２Ｏ－ｙＡｌ２Ｏ３－（７５－ｙ）ＳｉＯ２玻璃（Ａｌ２Ｏ３／Ｒ２Ｏ最高可达０．４,Ｒ２Ｏ＝Ｎａ２Ｏ＋Ｋ２Ｏ）在１４００￣１０００℃之间的粘度。铝在碱铝玻璃熔体中（Ａｌ２Ｏ３／Ｒ２Ｏ＝０）有一粘度最小值,即比照Ｋ２Ｏ／Ｒ２Ｏ的混合碱效应。尽管混合碱铝硅玻璃熔体粘度无最小值。但它是线性的。这表明随着Ａｌ２Ｏ３的引入量增加,混合碱效应减弱。将粘度变化结果与早期研究的电阻率相     

Keggin结构稀土硅钨钒杂多配合物的合成与性质研究

报道了通式为Ｋ１３Ｈ２［Ｌｎ（ＳｉＷ１０ＶＯ３９）２］·ｘＨ２Ｏ（Ｌｎ＝Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｎ）［简记为Ｌｎ（ＳｉＷ１０Ｖ）２］６种配合物的合成方法。并利用顺磁共振光谱、磁化率、Ｘ射线粉末衍射、差热热重分析和循环伏安－极谱方法研究了它们的性质。     

Li+(K+)/CO32-、B4O72-- H2O三元系298K时平衡液相的物化性质

研究了二个三元体系Ｌｉ＋／ＣＯ３２－、 Ｂ４Ｏ７２－Ｈ２Ｏ（１）和Ｋ＋／ＣＯ３（２－）、 Ｂ４Ｏ７（２－）－Ｈ２Ｏ（２） ２９８Ｋ时的相平衡液相的物化 性质（密度、折光率、粘度、电导率、ｐＨ值）。研究表明：这二个三元体系均属简单共饱型,无复盐或固溶体形 成。体系（１）的两段溶解度曲线对应于无水Ｌｉ２ＣＯ３和Ｌｉ２Ｂ４Ｏ７Ｈ２Ｏ结晶区,体系（２）的两段溶解度曲线对应于 Ｋ２ＣＯ３·３／２Ｈ２Ｏ和Ｋ２Ｂ４Ｏ７·４Ｈ２Ｏ结晶区。用经验公式对平衡液相的密度、折光率进行了计算,计算值与实验值非常 吻合,最大绝对偏差仅为０．００１１。     

含固溶体三元体系K_2SO_4-(NH4)_2SO_4-H_2O和KCl-NH_4Cl-H_2O溶解度的计算

含固溶体三元体系Ｋ２ＳＯ４－（ＮＨ４）２ＳＯ４－Ｈ２Ｏ和ＫＣｌ－ＮＨ４Ｃｌ－Ｈ２Ｏ溶解度的计算樊彩梅舒兰余华瑞石炎福（四川联合大学化工系,成都６１００６５）关键词固溶体电解质溶液溶解度１前言自１９７３年以来,美国物理化学家Ｋ．Ｓ．Ｐｉｔｚｅｒ在总结...     

The diffusion behavior of carbon in sputtered tungsten film and sintered tungsten block and its effect on diamond nucleation and growth

Diamond was done on sintered tungsten block with or without sputtered tungsten films. The effects of various depositing conditions, including methane concentration, temperature, pressure, the diamond seeding step and reaction time, on diamond growth were investigated in detail. The results show that the sputtered tungsten film has a dual effect on diamond growth. Firstly, after ultrasonication with diamond slurry, the tungsten film will adsorb a large number of diamond nanoparticles. Therefore, the nucleation density of diamond will be substantially improved. Secondly, the film will be carbonized during the deposition process and the carbon on the surface of the film will decrease. Methane concentration generally does not affect the carbonization level of the tungsten film but higher temperature will lead to a higher level of carbonization. The carbonization process of sputtered tungsten films during deposition is made up of two steps. Also, the nucleation surface of diamond was revealed. The nucleation surface was a layer of ultrasmooth and seamless nanocrystalline diamond film with high-quality and special surface architecture (tiny peaks arrays), which is potential to be applied in MEMS and field-emission devices. A potential method to prepare ultrasmooth nanocrystalline diamond films is proposed.     

Nucleation and growth of diamond films on single crystal and polycrystalline tungsten substrates

Silicon has been the most widely studied substrate for the nucleation and growth of CVD diamond films. However, other substrates are of interest, and in this paper, we present the results of a study of the biased nucleation and growth of diamond films on bulk single and polycrystalline tungsten. Diamond films were nucleated and grown, using a range of bias and reactor conditions, and characterized by Raman spectroscopy and scanning electron microscopy (SEM). High-quality (100) textured films (Raman FWHM<4 cm⁻¹) could be grown on both single and polycrystalline forms of the tungsten substrate. On carefully prepared substrates, by varying the bias treatment, it was possible to determine the nucleation density over a 4–5 order range, up to ∼10⁹ cm⁻². Raman measurements indicated that the diamond films grown on bulk tungsten exhibited considerable thermal stress (∼1.1 GPa), which, together with a thin carbide layer, resulted in film delamination on cooling. The results of the study show that nucleation and growth conditions can be used to control the grain size, nucleation density, morphology and quality of CVD diamond films grown on tungsten.     

Investigation of nucleation centres in diamond chemical vapour deposition with spatially resolved X-ray photoelectron spectroscopy

The nucleation of diamond films on silicon substrates deposited by hot filament chemical vapour deposition has been investigated for the first time with an X-ray photoelectron spectroscopy microscope. The distribution of carbon, oxygen, silicon and tungsten on the surface was imaged with a spatial resolution of 10 μm. Significant differences were found between untreated areas of the substrates and scratches created by a diamond tip. Our data reveal that material from the tip abraded in the scratching process is not of key importance for nucleation.     

Electrochemical reduction of Fe(ii) ions on different solid electrodes in fused ZnCl2-2NaCl mixture

The electrodeposition of Fe(II) in ZnCl₂-2NaCl melt at 450°C was studied at molybdenum and tungsten electrodes and the results are compared with those obtained at glassy carbon in previous work. The kinetics of the electrodeposition and electrocrystallization of iron were studied, showing that the process is quasireversible, and the values of the kinetic parameters ° and were obtained. Mass transport towards the electrode is a simple diffusion process and the diffusion coefficient was obtained by applying different electrochemical techniques. Potential step measurements indicate that instantaneous nucleation and growth phenomena play a part in the overall process.     

Flame synthesis of tungsten-doped titanium-dioxide nanoparticles using novel precursor combination of liquid titanium tetra-isopropoxide and solid tungsten mesh

Tungsten-doped titanium-dioxide (W-TiO₂) nanoparticles are successfully synthesized using a multiple-diffusion-flame burner with a separate center tube. Vaporized titanium tetra-isopropoxide (TTIP) precursor issues from a center tube to produce TiO₂ nanoparticles, while a tungsten mesh, suspended above the surrounding multiple over-ventilated hydrogen diffusion flames, serves as the solid-phase metal doping source. At a lower tungsten loading rate, W-TiO₂ nanoparticles are generated, as indicated by an obvious angle shift of 0.15° for the entire x-ray diffraction spectrum. However, at a higher tungsten loading rate, homogenous nucleation of WO_x occurs before or concurrently with TiO₂ nucleation, producing mixed nanopowders, permitting fewer tungsten ions to be doped into TiO₂. Ultraviolet–visible spectroscopic characterization reveals that the as-synthesized W-TiO₂ nanoparticles possess augmented absorbing ability in the visible-light wavelength range, where the band gap is reduced from 3.20 to 3.05 eV, compared with that for the nondoped TiO₂ nanoparticles.     

Nucleation and Growth of Diamond Films on Ni-Cemented Tungsten Carbide: Effects of Substrate Pretreatments

The nucleation and growth of diamond films on Nicemented carbide is investigated. Substrates made of WC with 6 wt% of Ni were submitted to grinding, and then to different pretreatments (scratching, etching, and/or decarburization) before diamond deposition. Diamond synthesis was carried out by hot-filament chemical vapor deposition (HFCVD) using a mixture of CH₄ (1% v/v) and H₂. Depositions were performed for different lengths of time with the substrates at various temperatures. The specimens were analyzed before and after deposition by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffractometry (XRD). Raman spectra showed that the phase purity of the diamond films was not affected by the presence of nickel on the substrate surface. After wet etching pretreatments, the nucleation of diamond was enhanced, mainly at the WC grain boundaries. Continuous films were obtained on scratched and etched substrates. The decarburizing treatment led to the formation of metallic tungsten and of brittle nicke–tungsten carbide phases. These phases reacted in the early stages of diamond film formation with gaseous carbon species with a parallel process which competes with stable diamond nucleus formation. The diamond film formed after long-term deposition on these samples was not continuous.     

钛基锡锑中间层上二氧化铅电沉积过程的研究

运用电化学手段研究了钛基锡锑中间层上二氧化铅的阳极电沉积过程.循环伏安曲线表明,二氧化铅的电沉积经历了晶核形成过程,通过恒电位阶跃暂态曲线可知,二氧化铅在Ti/SnO2-Sb2O5电极上的电沉积初始过程遵循扩散控制的瞬时成核和三维长大方式,且随着过电位的增加,电极表面上晶核数增多.     

Early Stages of Diamond-Film Formation on Cobalt-Cemented Tungsten Carbide

The surface composition of cemented tungsten carbide (WC-5.8 wt% Co) was studied by X-ray photoelectron spectroscopy (XPS), during the early stages of diamond-film deposition, by hot-filament chemical vapor deposition (HFCVD). The nucleated diamond films were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and automatic image analysis (AIA). The evolution of the surface composition of cemented tungsten carbide during the early stages of diamond-film deposition was strongly dependent on the substrate temperature. At relatively low temperature (750°C), cobalt-rich particles started to segregate at the substrate surface after a few minutes of diamond deposition. The conspicuous segregation of the binder partly inhibited the formation of stable diamond nuclei, through intense carbon dissolution or carbon segregation at the binder surface, but did not affect nucleic growth. At higher temperatures (940°C), no cobalt-rich particles formed at the substrate surface, even after 2 h of deposition. However, XPS results demonstrated the presence of cobalt in a surface layer, although in a lower amount than at 750°C. Nevertheless, the nucleation density of diamond at 940°C was much lower than at 750°C. Gaps between WC grains formed within 10 mins. Therefore, intergranular cobalt was removed at 940°C, a finding attributed to the etching performed by monohydrogen, rather than to binder evaporation. The time evolution of the substrate area fraction covered by diamond islands, S ( t ), was well described by Avrami kinetics for two-dimensional phase transformations, suggesting that diamond formation took place via a heterogeneous nucleation process. The S ( t ) functions exhibited a similar trend at 750° and 940°C, because the higher growth rate of diamond crystallites at higher temperature counteracted the slower nucleation rate at the higher temperature.     

氯化镁-氢氧化钠复合添加剂制备文石型碳酸钙

采用碳化法,使用氯化镁和氢氧化钠复合添加剂,制备含文石相的沉淀碳酸钙。采用X射线衍射（XRD）、透射电镜（TEM）对产物的晶型和形貌进行表征。讨论了氢氧化钠添加比例、氢氧化钙浓度以及碳化反应温度等工艺条件对实验结果的影响,并分析了过程的反应机理。结果表明：产物中的文石相来自于碳酸钙在氢氧化镁沉淀上的异相成核和生长,方解石相来自于碳酸钙在溶液中的均相成核和生长;氢氧化钠的加入降低了溶液中碳酸钙的过饱和度,抑制了均相成核过程,降低了氯化镁的添加比例。在碳化反应温度为30 ℃、氢氧化钙浓度为1.7~ 2.0 mol/L、氢氧化钠与氯化镁物质的量比为2.6条件下,对文石型碳酸钙的生成较为有利。     

微晶玻璃的组成及热处理制度与热膨胀系数关系的研究

采用传统的熔体冷却法制得Li2O-A l2O3-SiO2系统的基础玻璃。利用DTA制定了相应的热处理制度,测定了玻璃热处理前后的热膨胀系数,并利用XRD研究了经热处理后的微晶玻璃的晶体相组成。结果表明:具有复合晶核剂TiO2 ZrO2和采用二步热处理制度所得的微晶玻璃热膨胀系数更小,且随着二步热处理制度温度的升高,微晶玻璃热膨胀系数更小,相应的玻璃结构也越致密。