Size-controlled synthesis of monodispersed mesoporous α-alumina spheres by a template-free forced hydrolysis method

We demonstrated the formation of monodispersed spherical aluminum hydrous oxide precursors with tunable sizes by controlling the variables of a forced hydrolysis method. The particle sizes of aluminum hydrous oxide precursors were strongly dependent on the molar ratio of the Al(3+) reactants (sulfates and nitrates). In addition, the systematic phase and morphological evolutions from aluminum hydrous oxide to γ-alumina (Al(2)O(3)) and finally to α-Al(2)O(3) through thermal dehydrogenation were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). After annealing the amorphous aluminum hydrous oxide in air at 900 °C and 1100 °C for 1 h, we observed complete conversion to phase-pure γ- and α-Al(2)O(3), respectively, while maintaining monodispersity (125 nm, 195 nm, 320 nm, and 430 nm diameters were observed). Furthermore, both γ- and α-Al(2)O(3) were found to be mesoporous in structure, providing enhanced specific surface areas of 102 and 76 m(2) g(-1), respectively, based on the Brunauer-Emmett-Teller (BET) measurement.     

AIN纳米微粉的微波合成

Nanometer aluminum nitride powder with purity higher than 98wt% and diameter in the range of 5-80nm has been obtained by microwave heating using α-Al2O3、Al(OH)3、 colloidal Al(OH)3 as the source for aluminum, and phenolformaldehyde resin, char, nanometer carbon black powder as the source for carbon, respectively. The effect of the type of starting materials and synthesis conditions on the purity and the size of the nanometer AlN powder has been analyzed in this paper.     

Characterization of Laser-Arc deposited multilayer systems by means of AES, Factor Analysis and XPS

In a vacuum chamber at 5 · 10^–4 Pa, multilayer systems (single layer thickness 20 nm) consisting of Ti/C and Al/C, respectively, have been deposited on Si (111) disks by the laser assisted coating (Laser-Arc). Structure and composition have been investigated by means of Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Auger Electron Spectroscopy (AES) in conjunction with Factor Analysis. AES depth profile measurements through the outermost part of the layers show for both the Ti/C and the Al/C samples a regular structure of the layer sequence metal/ carbon with a constant distance along the sample normal and sharply formed interfaces. In the metallic layers an oxygen enrichment was found, which is more intensive in the Ti/C deposit than in the Al/C one. By means of Factor Analysis in the evaluation of the differentiated spectra as a function of sputtering time, the formation of carbides at the metal/carbon interfaces has been detected. However, in the present state of the investigations it can not be decided, whether the observed carbide formation is the result of the energy impact due to ion sputtering or the coating fabrication process itself.     

Electrospray ionization with aluminum foil: A versatile mass spectrometric technique

In this study, we developed a novel electrospray ionization (ESI) technique based on household aluminum foil (Al foil) and demonstated the desirable features and applications of this technique. Al foil can be readily cut and folded into desired configuration for effective ionization and for holding sample solution in bulk to allowing acquisition of durable ion signals. The present technique was demonstrated to be applicable in analysis of a wide variety of samples, ranging from pure chemical and biological compounds, e.g., organic compounds and proteins, to complex samples in liquid, semi-solid, and solid states, e.g., beverages, skincare cream, and herbal medicines. The inert, hydrophobic and impermeable surface of Al foil allows convenient and effective on-target extraction of solid samples and on-target sample clean-up, i.e., removal of salts and detergents from proteins and peptides, extending ESI device from usually only for sample loading and ionization to including sample processing. Moreover, Al foil is an excellent heat-conductor and highly heat-tolerant, permitting direct monitoring of thermal reactions, e.g., thermal denaturation of proteins. Overall, the present study showed that Al-foil ESI could be an economical and versatile method that allows a wide range of applications.     

激光烧蚀硅酸盐的材料产生氧化硅氧化铝复合团簇

采用习飞行时间质谱技术,用308nm准分子激光烧蚀不同硅铝比的ZSM-5沸石,产生了氧化硅氧化铝复合团簇.在负离子通道测得含铝的新团簇系列[(SiO~2)~n~-~1(ALO~2)]^-和[(SiO~2)~nOAl]^-,讨论了这些系列的丰度分布和样品硅铝比之间的关系.由于AlO~2有较高电负性,激光烧蚀产生的团簇负离子系列[(SiO~2)~n~-~1(AlO~2)]^-具有以AlO~2为生长核心的生长机理。     

A reactor for high-temperature pyrolysis and oxygen isotopic analysis of cellulose via induction heating

A reactor for converting cellulose into carbon monoxide for subsequent oxygen isotopic analysis via continuous flow isotope ratio mass spectrometry is described. The system employs an induction heater to produce temperatures >or=1500 degrees C within a molybdenum foil crucible positioned by boron nitride (BN) spacers within a quartz outer sleeve. For samples of a homogeneous working standard cellulose between 300 and 400 microg in size, the blank/signal ratio is <5%, and the long-term precision is 0.30 per thousand (N = 232). For samples of 30 to 100 microg in size, a gas pressure sintered silicon nitride (Si(3)N(4)) outer sleeve replaces the quartz sleeve, the BN spacers are not used, and 6.0-grade carrier He must be used to minimize the blank signal. With these modifications a blank/sample ratio of <5% and long-term precision of 0.30 per thousand (N = 144) are obtained. These results are similar to those achieved using standard high-temperature furnaces, but the reactor is simpler to pack, the system is more economical to run, and samples as small as 30 microg cellulose may be measured. For both reactors memory is significant in the subsequent sample and is believed to be due to exchange with reactor oxygen at temperatures above 1000 degrees C. Further applications might include online preparation of other materials requiring temperatures of 1500-2600 degrees C.     

Hysteresis loss as a measure of metal–rubber adhesion

As in the case of reinforcing filler-induced increase in hysteresis in rubbers, placement of aluminum (A1) foil to the surface of a rubber blend of epichlorohydrin rubber and carboxylated nitrile base induces increased hysteresis of the rubber due to adhesion between Al and the rubber blend. Changes in hysteresis loss due to Al foil can be correlated with the peel strength of Al-rubber-Al joints. © 1995 John Wiley & Sons, Inc.     

涂碳铝箔对磷酸铁锂电池性能影响研究

本文研究了使用涂碳铝箔作为正极集流体磷酸铁锂电池的性能。研究对比了使用普通铝箔和涂层铝箔的10 Ah软包磷酸铁锂电池的主要性能。研究表明:使用涂层铝箔不但可以提高磷酸铁锂材料的粘结性,而且使用导电涂层可以有效降低正极材料和集流体的接触内阻,从而减小电池内阻,提高电池倍率性能。与使用普通铝箔作为集流体相比,通过使用涂碳铝箔可以使得电池的内阻降低65%左右,但是,磷酸铁锂正极材料的克容量却偏低约5~10 mAh·g-1,首次效率也偏低4%左右;在快速放电15C倍率下,使用涂碳铝箔的电芯比使用普通铝箔容量提高约15%左右,10C放电倍率下,平台增加0.3~0.4 V;使用涂碳铝箔电芯的常温自放电率较高,但容量恢复率也较高;550周循环下,使用涂碳铝箔可以使得电池的循环性能提高约1%。而在电池低温性能方面,使用涂碳铝箔对低温性能并无改善。     

涂碳铝箔对磷酸铁锂电池性能影响研究

本文研究了使用涂碳铝箔作为正极集流体磷酸铁锂电池的性能。研究对比了使用普通铝箔和涂层铝箔的10 Ah软包磷酸铁锂电池的主要性能。研究表明：使用涂层铝箔不但可以提高磷酸铁锂材料的粘结性,而且使用导电涂层可以有效降低正极材料和集流体的接触内阻,从而减小电池内阻,提高电池倍率性能。与使用普通铝箔作为集流体相比,通过使用涂碳铝箔可以使得电池的内阻降低65%左右,但是,磷酸铁锂正极材料的克容量却偏低约5~10 mAh·g^-1,首次效率也偏低4%左右;在快速放电15C倍率下,使用涂碳铝箔的电芯比使用普通铝箔容量提高约15%左右,10C放电倍率下,平台增加0.3~0.4 V;使用涂碳铝箔电芯的常温自放电率较高,但容量恢复率也较高;550周循环下,使用涂碳铝箔可以使得电池的循环性能提高约1%。而在电池低温性能方面,使用涂碳铝箔对低温性能并无改善。     

纳米ZnO薄膜的制备及其可见光催化降解甲基橙

采用溶胶-凝胶方法制备ZnO透明溶胶, 在铝箔上涂膜后经500 ℃处理制得具有可见光响应的纳米ZnO薄膜光催化剂. 以甲基橙模拟有机污染物, 在可见光下研究了薄膜的降解性能, 结果表明, 用一片有效面积为200 cm2的ZnO/Al薄膜作为催化剂, 甲基橙的降解率达到96.3％, 比ZnO负载在玻璃上制得的ZnO/glass薄膜催化剂活性高得多. 采用扫描电镜与原子力显微镜对ZnO/Al薄膜制备条件进行了表征, 结果发现多孔ZnO/Al薄膜比致密ZnO/Al薄膜具有更高的活性, 实验制备的具有高活性的ZnO/Al薄膜颗粒平均直径为52.2 nm. 采用本方法制备的ZnO/Al薄膜是一种具有应用前景的, 能在可见光下降解有机物的有效光催化剂.     

Formation of Al2O3–BaTiO3 nanocomposite oxide films on etched aluminum foil by sol–gel coating and anodizing

Barium titanate BaTiO₃ (BT) sol was dip-coated on the etched aluminum foils by a sol–gel process. After annealed at 600 °C in air, the foils were anodized in ammonium adipate solution. The voltage–time variations during anodizing were monitored. The structure, composition, and electric properties of the anodic foils were investigated. The obtained foils were fabricated into aluminum electrolytic capacitors and the load and shelf life test were measured. It was found that the slope of the voltage–time curve of aluminum foil covered with BT films became steeper. A triple layer of Al/Al₂O₃/BT was formed after anodizing Al/BT foil. The specific capacitance and the product of specific capacitance and withstanding voltage of anodic foil with a BT coating were about 46.36% and 38.90% larger than that without a BT coating. After the load life and shelf life of 2500 h at 85 °C, two kinds of capacitors have similar behaviores and meet with Nichicon standard of Japan. From the results, BaTiO₃ is promising to be used as the dielectric of aluminum electrolytic capacitor to increase the specific capacitance.     

铝含量对含铝碳化硅陶瓷先驱体结构和性能的影响

采用不同比例的乙酰丙酮铝[Al(AcAc)3]与聚硅碳硅烷(PSCS)反应制备含铝碳化硅陶瓷的先驱体聚铝碳硅烷(PACS). 采用气相凝胶色谱(GPC)、化学分析和红外等手段对不同铝含量的PACS组成和结构进行了表征, 研究了铝含量对PACS结构和性能的影响. 结果表明, 随着铝含量的增加, PACS的氧含量增加, 分子量分布变宽, 主要活性基团Si—H键的含量降低, PACS的可纺性降低. 当Al(AcAc)3/PSCS(质量比)大于20%以后, PACS不可纺. 热重-差热分析(TG-DTA)的研究表明: 当制备PACS的Al(AcAc)3/PSCS(质量比)大于4%, PACS在N2中400～560 ℃之间的失重明显降低. 铝含量在0.4～0.7 wt%的PACS, 制备的Si-Al-C-O纤维抗张强度最高. Al(AcAc)3/PSCS＝6 wt%时制备的PACS, 烧结的SiC(Al)纤维最致密.     

Effect of pH on the aluminum salts hydrolysis during coagulation process: formation and decomposition of polymeric aluminum species

Effect of pH on the aluminum chloride hydrolysis at low concentration was investigated in detail by electrospray ionization (ESI) mass spectrometry. In particular, formation and decomposition processes of polymeric aluminum species were discussed. When coagulant AlCl(3) was diluted to normal coagulant dose (1.5 x 10(-4) mol/L), hydrolysis occurred immediately. Monomeric and dimeric aluminum species were the main products at pH 4.0. With pH increasing, hydrolysis and polymerization processes were accelerated. Monomeric and dimeric aluminum species hydrolyzed and polymerized into small polymeric aluminum species (Al(3)-Al(5) species) at pH 4.8. Through aggregation and self-assembly, the small polymeric aluminum species polymerized into median polymeric species (Al(6)-Al(10) species) at pH 5.0. In the same way, small and median polymeric aluminum species further aggregated into large polymeric species (Al(11)-Al(21) species). When pH was up to 5.8, metastable median and large polymers species decomposed into small aluminum species, then further disaggregated into dimeric species. With pH increased to 6.4, majority of aluminum species formed to Al(OH)(3) amorphous flocs. Accordingly, coagulant hydrolysis mechanism from polymerization toward decomposition was proposed. Furthermore, formation and decomposition of polymeric aluminum species in AlCl(3) solution followed the "Core-links" model, while those of Keggin-Al(13) species in polyaluminum solution was based on the "Cage-like" model.     

溶胶-凝胶法制备纳米氢氧化铝溶胶

研究了利用铝酸钠溶液碳酸化产生的沉淀, 经胶溶作用制备出纳米氢氧化铝溶胶的过程. 分析了铝酸钠溶液滴加到大量碳酸氢钠溶液中时发生的反应. X射线衍射研究结果表明, 在纳米氢氧化铝溶胶制备过程中, 从无定形氢氧化铝沉淀到拟薄水铝石的晶型转变过程是氢氧化铝沉淀胶溶时溶解再析出的过程. 将碳酸氢钠加入到苛性比为1.7的铝酸钠溶液中, 中和至苛性比为1.3后, 溶液诱导期中的紫外光谱显示270 nm处的Al(OH)3-6吸收增强. 经与含铝原子六配位的晶体紫外光谱对比后表明, 在铝酸钠分解生成氢氧化铝的过程中, 其铝的配位结构从四配位转化为六配位. 拟薄水铝石溶胶粒子的形貌与胶溶所用的酸和分散剂有关.     

Preliminary study on air pollution source identification in Xinzhen,Beijing, using NAA and PIXE

A total of 178 aerosol samples in two size fractions, PM10-2.5 (coarse) and PM2.5 (fine), were collected on nucleopore films using a Gent stacked filter unit sampler at the Graduate School of China Nuclear Industrial Group during May 2007 to November of 2009. Black carbon was determined by a reflectometer. A total of 16 elements, Mg, Al, S, Si, P, Cl, Ca, K, Ti, Mn, Fe, Ni, Cu, Zn, As and Pb, were determined by Particle Induced X-ray Emission. Mg, Al, Ca, K and Mn were also determined by Neutron Activation Analysis. Concentrations of all these elements were used to identify possible pollution sources and directions of the airborne particulate matter by means of softwares PMF and CPF. Some extraordinary events, such as sandstorms, firework and transboundary fire smoke were pinpointed by a combination of time series of multielement, relevant meteorological data and softwares Wind rose, Hysplit, and Google earth.     

Development toward a double focusing isotopic separator for noble gas isotope enrichment

A double focusing sector field mass filter used in Nier–Johnson geometry has been built in order to perform Kr isotope enrichment for ⁸¹Kr and ⁸⁵Kr isotopes. The principle consists in implanting Kr⁺ ions accelerated at 7 keV in Al foils after separation using the magnetic sector. A specific ion source has been designed capable of generating high Kr⁺ ion beams (>0.5 μA) to transfer into the collecting Al foils in 3 to 5 h significant fractions of large Kr samples (10¹⁵ to 10¹⁶ atoms) initially introduced in the instrument. Implanted Kr isotopes can be further selectively released from the Al foil by surface ablation using an infrared laser beam. Implantation yields and enrichment factors are measured using a conventional mass spectrometer. Copyright © 2016 John Wiley & Sons, Ltd.     

D4(H)/D4(V) silicone: a replica material with several advantages for nanoimprint lithography and capillary force lithography

Reported are demonstrations that D(4)(H)/D(4)(V) silicone (the product of the platinum-catalyzed hydrosilylation reaction between tetramethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane) is useful and practical as a replica material for both nanoimprint lithography (NIL) and capillary force lithography (CFL). The multiple advantageous properties of this extremely cross-linked material include UV transparency (for photo NIL and photo CFL), thermal stability (for high printing temperatures), high modulus (for high printing pressures), low surface energy (for easy demolding), and low viscosity precursors (for replicating small scale features). The replication performance of this material was tested using Blu-ray discs with sub-25 nm features and anodized aluminum foil with sub-10 nm features. Structures of ～5 nm length scale on the surface of the anodized Al were replicated using D(4)(H)/D(4)(V) silicone as a mold material for CFL with a photocurable epoxy resin and for NIL with poly(methyl methacrylate) (PMMA). Features (holes in the anodized aluminum) with aspect ratios of greater than 9 were replicated.     

氢氧化钾法与硫酸法制备硫酸铝钾的区别探讨

研究了氢氧化钾和硫酸溶解铝箔制备十二水合硫酸铝钾的区别,通过返滴定法测定制备过程中各阶段的铝含量,深入分析了实验过程中的相关物料守恒,发现氢氧化钾法在铝箔溶解阶段由于副反应形成Al(OH)3沉淀,导致最终产率很低,进行搅拌及降低体系浓度可很大程度上提高产率,不过仍低于硫酸法。此外,硫酸法在实验操作上也相对更简捷。因此推荐学生使用硫酸法来制备十二水合硫酸铝钾。     

Investigation of mechanical properties of anodized aluminum using dilatometric measurements

Mechanical properties of anodized aluminum were studied using the results of dilatometric measurements of thermal expansion of anodized Al (the symmetric structure Al(2)O(3)-Al-Al(2)O(3)). The 100-microm-thick Al(2)O(3 )oxide layer was formed in 4% aqueous solution of oxalic acid in the galvanostatic regime at a current density of 20 mA cm(-2). Measurements of thermal expansion of anodized Al (Al and Mg alloy of 2.7-3.2%, and 0.3-0.6% Mn, and 0.5-0.8% Si) with the thickness of initial Al from 0.6 to 3.7 mm and ceramic from Al(2)O(3) in the temperature range of 20-500 degrees C were conducted using an automatic quartz dilatometer. Intrinsic stress in the Al layer, the values of the modulus of elasticity, and the porosity of Al oxide formed on Al of different thickness are calculated.     

Characterization of aluminum species with nitrate, perchlorate and sulfate ions in the positive and negative ion mode by electrospray ionization mass spectrometry

The application of electrospray ionization mass spectrometry (ESI-MS) for aluminum speciation in the positive and negative ion modes was discussed. Aluminum nitrate, perchlorate and sulfate solutions were measured by ESI-MS. In the positive ion mode, aluminum species containing anions (Al-L; L=NO3, ClO4 and SO4) were identified, while [Al(OH)2(H2O)n]+ (n=2-4) were the main species. The affinity of the anions with Al3+ estimated by ESI-MS was consistent with the hardness of the anions (hard and soft acids and bases principle) and the results from 27Al nuclear magnetic resonance studies. This indicates that the results observed from the positive ion mode preserved the chemical state of aluminum in the solution. In the negative ion mode, [Al(OH)4-nLn]- (n=0-2, L=NO3, ClO4) were the main species, which were considered to be converted from positive aluminum species, [Al(OH)(H2O)n]+ (n=2-4), by the successive addition of anions. Anions did not only attach to one aluminum ion but also bridged two aluminum ions. In Al2(SO4)3 solution, the behavior of SO4(2-) in the negative ion mode differed from that of NO3- and ClO4-. This may reflect the affinity of SO4(2-) with Al3+ in the solution or in the mass spectrometer or in both. Finally, detection mechanisms for the aluminum species in the solution are proposed for both the positive and negative ion modes. It is shown that ESI-MS can be used to observe the interaction between Al3+ and anions. We show the importance of the interpretation of the results by ESI-MS for obtaining new information of the metal species in the solution.