不锈钢基底上TiO2薄膜型光催化剂的制备和化学结构

采用钛酸正丁酯作为前驱体,通过溶胶-凝胶法在不锈钢基片上制备了TiO2纳米薄膜。利用俄歇电子能谱(AES)和紫外反射光谱等研究手段,对TIO2薄膜的化学结构及基底材料界面相互作用进行了系统研究。结果发现,在不锈钢基底上形成的TiO2薄膜与基底材料发生了明显的界面扩散反应。在TiO2薄膜的形成过程中,不锈钢中Fe元素向TiO2薄膜层扩散,并与从大气氛中扩散到界面的氧发生化学反应,形成铁氧化物界面过渡层。界面氧化过程,导致了Fe向样品表面的偏析和扩散。在高温热处理过程中,Fe可以扩散到TiO2薄膜的表面。薄膜催化剂的紫外反射光谱表明,界面扩散反应导致了Fe扩散进入TiO2薄膜的晶格,从而改变了薄膜催化剂的光吸收性能。     

XPS depth profile study of porous zirconia films deposited on stainless steel by spray pyrolysis: the problem of substrate corrosion

Zirconia (ZrO₂) films of tissue‐like structure and narrow pore size distribution have been deposited by spray pyrolysis using aqueous zirconyl chloride octahydrate (ZrOCl₂·8H₂O) precursor solutions. Stainless‐steel sheets, protected or unprotected by a ZnO barrier layer, have been used as the substrate material held at 473 K. The ZnO barrier layers have been deposited on the stainless steel held at 523 K by spray pyrolysis using a zinc acetate precursor. Their property of corrosion protection to stainless steel has been proved by electrochemical polarization measurements in 0.5 M NaCl solution. A complementary study of XPS (depth profiling, mapping) and x‐ray diffraction has shown that the unprotected steel substrates were corroded during ZrO₂ film post‐annealing in air at T ≥ 773 K, whereas steel substrates protected with a compact barrier layer of crystalline ZnO before ZrO₂ film deposition did not show surface corrosion even after annealing up to 997 K. Copyright © 2004 John Wiley & Sons, Ltd.     

Photo-Induced Hydrophilicity of TiO<Subscript>2</Subscript> Films Deposited on Stainless Steel via Sol-Gel Technique

The photo-induced hydrophilicity of TiO₂ films deposited on stainless steel substrates and silicon wafers using two different sol-gel routes has been investigated. The results indicate that crystalline titanium oxide films with excellent hydrophilic properties can be obtained on silicon wafer with both routes. XPS and XRD data reveal that films deposited on stainless steel exhibit crystallization features similar to those of films deposited on silicon wafers, and only differ by their oxidation degree owing to a TiO₂ reduction process associated to a diffusion of iron ions during deposition of the acidic sol and/or high temperature post-treatment. Consequently, hydrophilic properties of films deposited on stainless steel are inhibited. The deposition of a SiO_x barrier layer at the film/substrate interface allows preventing such a detrimental substrate influence. A low temperature deposition route of the TiO₂ film associated to the presence of a barrier layer yields best results in preventing iron contamination of the films.     

Characterization of interfaces of alumina – high alloyed steels by SST and AES depth profiling

Thin alumina films, deposited at 280°?C on several high alloyed steels by low pressure metal-organic chemical vapour deposition (LP-MOCVD), were annealed at 0.17 kPa in a nitrogen atmosphere for 2, 4 and 17 h at 600 and 800°?C. The effect of the annealing process on the adhesion of the thin alumina films was studied using a scanning scratch tester (SST) and Auger electron spectroscopy (AES). The best adhesion properties were obtained with commercial oxide dispersion strengthened (ODS) high temperature alloys, especially type PM 3030. From the “normally” high alloyed stainless steels, type AISI-321 showed the best properties. The other stainless steel – alumina combinations showed after a thermal treatment a decrease of the critical load, L_c. Using ODS alloys as the substrate resulted in an increased L_c. AES-studies revealed that the increased L_c can be explained by 1) the presence of sulphur trapping elements, avoiding segregation of sulphur near the interface which could have a detrimental effect on scale adherence, and 2) titanium and carbon enrichment at the interface resulting in a beneficial effect on the adherence between the oxide and the substrate.     

Interfacial characterization of chemical solution‐deposited thin films of PbSe on GaAs(100)

The microstructure and composition of the interfacial layer between chemically deposited PbSe and GaAs substrates were studied using high‐resolution transmission electron microscopy (HRTEM), Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy (XPS) and energy‐filtered TEM. The thickness of the interfacial layer varied significantly from direct contact of the film with the substrate to 5 nm in the thickest regions. The results established the presence of a discontinuous, amorphous intermediate layer of Ga₂O₃ at the PbSe/GaAs interface. Copyright © 2008 John Wiley & Sons, Ltd.     

Investigating Pb diffusion across buried interfaces in Pb(Zr0.2Ti0.8)O3 thin films via time‐of‐flight secondary ion mass spectrometry depth profiling

The diffusion of Pb through Pb(Zr_0.2Ti_0.8)O₃(PZT)/Pt/Ti/SiO₂/Si thin film heterostructures is studied by using time‐of‐flight secondary ion mass spectrometry depth profiling. The as‐deposited films initially contained 10 mol% Pb excess and were thermally processed at temperatures ranging from 325 to 700°C to promote Pb diffusion. The time‐of‐flight secondary ion mass spectrometry depth profiles show that increasing processing temperature promoted Pb diffusion from the PZT top film into the buried heterostructure layers. After processing at low temperatures (eg, 325°C), Pb⁺ counts were low in the Pt region. After processing at elevated temperatures (eg, 700°C), significant Pb⁺ counts were seen throughout the Pt layer and into the Ti and SiO₂ layers. Intermediate processing temperatures (400, 475, and 500°C) resulted in Pb⁺ profiles consistent with this overall trend. Films processed at 400°C show a sharp peak in PtPb⁺ intensity at the PZT/Pt interface, consistent with prior reports of a Pt₃Pb phase at this interface after processing at similar temperatures.     

Epoxidation of styrene with molecular oxygen catalyzed by a novel oxovanadium(IV) catalyst containing two different kinds of ligands

A novel type of oxovanadium(IV) 8‐hydroxyquinoline (8‐Q) complex and oxovanadium(IV) acetylacetonate (acac) complex were synchronously anchored on to amino‐modified SBA‐15 (named VO(acac:8‐Q)‐SBA‐15) and examined as a catalyst for styrene oxidation. The structure of the synthesized catalyst was characterized by means of X‐ray diffraction (XRD), FT‐IR, diffusion reflection UV–visible, inductively coupled plasma atomic emission spectroscopy (ICP‐AES), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). Characterizations with FT‐IR, diffusion reflection UV‐visible, ICP‐AES and TG suggested the incorporation of oxovanadium(IV) complex in amino‐modified SBA‐15. XRD and SEM results indicated that SBA‐15 remained intact throughout the grafting procedure. It was found that VO(acac:8‐Q)‐SBA‐15 catalyst was more active than single‐ligand catalysts VO(acac)₂‐SBA‐15 and VO(8‐Q)₂‐SBA‐15 and that the product selectivity varied in cases of different oxidants. The catalyst VO(acac:8‐Q)‐SBA‐15 with two different ligands showed high yield of styrene oxide (45.8%) and good recoverability when using air as oxidant. Copyright © 2012 John Wiley & Sons, Ltd.     

Microstructural evolution of protective La–Cr–O films studied by transmission electron microscopy

Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS) were performed to study the microstructural evolution of La–Cr–O thin films deposited by radio frequency (RF)-magnetron sputtering on stainless steel substrates. Chromium L edges and oxygen K edges are analyzed to determine the valence states of the chromium and elucidate the phase evolution of the thin film. The as-deposited amorphous thin film crystallized to LaCrO₄ and finally transformed to the LaCrO₃ stable phase during annealing at 800°C. An intermediate Cr/Mn oxide layer was formed in all annealed samples. The thickness of this oxide layer stabilizes after 700°C, which indicates that the LaCrO₃ thin film plays a role in inhibiting the growth of an oxide layer on the metal surface.     

Effect of thermal annealing of poly(3-octylthiophene) films covered stainless steel on corrosion properties

The effect of thermal annealing of poly(3-octylthiophene) (P3OT) coatings on the corrosion inhibition of stainless steel in an NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl₃) as oxidant. P3OT films were deposited by drop-casting technique onto 304 stainless steel electrode (304SS). 304SS coated with P3OT films were thermally annealed during 30 h at different temperatures (55°C, 80°C, and 100°C). The corrosion resistance of stainless steel coated with P3OT in 0.5 M NaCl aqueous solution at room temperature was investigated by using potentiodynamic polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. The results indicated that the thermal treatment at 80°C and 100°C of P3OT films improved the corrosion resistance of the stainless steel in NaCl solution; the speed of corrosion diminished in an order of magnitude with regard to the 304SS. In order to study the temperature effect in the morphology of the coatings before and after the corrosive environment and correlate it with corrosion protection, atomic force microscopy and scanning electron microscopy were used. Morphological study showed that when the films are heated, the grain size increased and a denser surface was obtained, which benefited the barrier properties of the film.     

Tin Oxide Thin Film with Three‐Dimensional Ordered Reticular Morphology as a Lithium Ion Battery Anode

Three‐dimensional (3D) reticular SnO₂ thin films deposited on copper and stainless steel substrates were prepared by the electrostatic spray deposition (ESD) technique. The 3D reticular SnO₂ film exhibit a high reversible capacity near 300 mAh g^?1 up to the 50th cycle.     

Effect of sulfate and dissolved hydrogen on oxide films on stainless steel in high-temperature water

In the present paper, we focus on the influence of sulfate ion impurity and dissolved hydrogen on the protective ability of the oxide film on stainless steel in high-temperature water. For the purpose, the electrical and electrochemical properties of oxide films formed on AISI 316L NG in simulated boiling water reactor crack conditions (10 ppm sulfate purged with N₂ + 0.01 or 0.5% H₂) were characterized by in situ electrochemical impedance spectroscopy (EIS). In addition, the surface and in-depth composition of the oxide films has been estimated by ex situ Auger electron spectroscopy (AES). The quantitative assessment of the protective ability of the oxide is based on an interpretation of the electrochemical impedance data per the mixed-conduction model. A novel procedure for the estimation of kinetic and transport parameters that involves comparison of the model equations to both EIS and AES results is proposed and tested. Based on the parameter values, the effect of sulfate and dissolved hydrogen on the processes of film growth and dissolution is discussed in view of an approach to the initiation of stress corrosion cracks.     

Thickness and temperature‐dependent study of Co/Si interface

Thin films of cobalt (10, 40, and 100 nm) are deposited on Si substrate by electron beam physical vapor deposition technique. After deposition, 4 pieces from each of the wafers of silicon substrate were cut and annealed at a temperature of 200°C, 300°C, and 400°C for 2 hours each, separately. X‐ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) are used to study the structural and morphological characteristics of the deposited films. To obtain TEM images, Co films are deposited on Cu grids; so far, no such types of TEM images of Co films are reported. Structural studies confirm nanocrystalline nature with hexagonal close packed structure of the deposited Co film at lower thickness, while at higher thickness, film structure transforms to amorphous with lower surface roughness value. The particle sizes in all the cases are in the range of 3 to 5 nm. Micro‐Raman spectroscopy is also used to study the phase formation and chemical composition as a function of thickness and temperature. The results confirm that the grown films are of good quality and free from any impurity. Studies show the silicide formation at the interface during deposition. The appearance of new band at 1550 cm⁻¹ as a result of annealing indicates the structural transformation from CoSi to CoSi₂, which further enhances at higher annealing temperatures.     

Ti/ZrN2/Si薄膜界面扩散反应的研究

利用直流磁控反应溅射法在Si基底上制备了Ti/ZrN2/Si多层薄膜，利用俄歇深度剖析和线形分析研究了真空热处理前后膜层间的界面状态及相互作用.研究结果表明，Ti膜和ZrN2膜均在沉积过程中发生了界面扩散作用，真空热处理可以显著地增强Ti/ZrN2/Si膜层间的界面扩散和化学反应，并分别在界面层生成了TiNx和SiNx等物种.     

稀碱溶液中水热法制备柔性TiO2纳米须薄膜的生长机制及表征

以柔性不锈钢基底上经磁控溅射沉积的钛膜为钛源, 在1 mol·L^-1的低浓度NaOH溶液中水热法制备了朝基底上方取向生长的大长径比柔性TiO₂纳米须薄膜, 考察了钛膜沉积条件对纳米须薄膜的影响, 系统研究了水热反应条件对薄膜生长过程的影响及TiO₂纳米须薄膜的形成机制. 通过场发射扫描电镜(FESEM)、X射线能谱仪(EDS)、高分辨透射电子显微镜(HRTEM)、X射线衍射仪(XRD)等对样品进行了表征. 结果表明, 与室温沉积的钛膜相比, 600 ℃下沉积的钛膜水热后得到的纳米线薄膜与基底的附着力更好. 所得TiO₂纳米须为单晶锐钛矿, 经由Na₂Ti₂O₄(OH)₂、H₂Ti₂O₅·H₂O转变而来. 纳米须形成于水热阶段, 平行于Na₂Ti₂O₄(OH)₂的(100)晶面择优取向生长, 纳米须经历了纳米片→纳米线束→纳米线的裂解生长过程. 朝基底上方取向生长的纳米须薄膜的形成是低浓度NaOH溶液与较高水热温度(220 ℃)协同作用的结果. 进一步在Na₂SO₄溶液中研究了薄膜电极的光电化学性能, 结果表明, TiO₂纳米须薄膜的光电性能明显优于零维纳米颗粒薄膜和二维纳米片薄膜, 显示了良好的应用前景.     

Interface formation of Al2O3 on n‐GaN(0001): Photoelectron spectroscopy studies

Al₂O₃ insulator layers were deposited step by step by the physical vapor deposition (PVD) method onto gallium nitride in the wurtzite form, n‐type and (0001)‐oriented. The substrate surface and the early stages of Al₂O₃/n‐GaN(0001) interface formation were characterized in situ under ultra‐high vacuum conditions by X‐ray and ultraviolet photoelectron spectroscopy (XPS, UPS). The electron affinity (EA) of the substrate cleaned by annealing was 3.6 eV. Binding energies of the Al 2p (76.0 eV) and the O 1s (532.9 eV) confirmed the creation of the Al₂O₃ compound in the deposited film for which the EA was 1.6 eV. The Al₂O₃ film was found to be amorphous with a bandgap of 6.9 eV determined from the O 1s loss feature. As a result, the calculated Al₂O₃/n‐GaN(0001) valence band offset (VBO) is ?1.3 eV and the corresponding conduction band offset (CBO) 2.2 eV.     

Oxidation, Diffusion and Segregation in CuNi(Mn) Films Studied by AES

 The surface and in-depth compositions of sputter-deposited Cu_0.57Ni_0.42Mn_0.01 thin films were studied by Auger electron depth profiling after thermal treatment. The samples were thermally cycled to maximum temperatures of 300 °C to 550 °C in air, argon and forming gas (N₂, 5 vol. % H₂). Linear least-squares fit to standard spectra and factor analysis were applied to separate the overlapping Auger transitions of Cu and Ni. Under bombardment by 4 keV argon ions, CuNi(Mn) layers display bombardment-induced surface enrichment of Ni in the same extent as binary CuNi alloys. At sufficiently high oxygen partial pressures, a duplex oxide layer is formed and a thick surface copper oxide overgrows the initial nickel oxide. In reducing atmosphere selective oxidation of manganese takes place. A capping NiCr layer prevents CuNi(Mn) from being oxidized, but the film configuration is degraded with increasing annealing temperature due to formation of a surface chromium oxide and diffusion of Ni from the CuNi(Mn) layer into the NiCr/CuNi(Mn) interface.     

Structural and photoelectrochemical characterization of MWCNT-TiO2 matrices sensitized with Bi2S3

Structural and photoelectrochemical characterization of multiwall carbon nanotubes–titanium oxide (MWCNT-TiO₂) matrices, sensitized with bismuth sulfide (Bi₂S₃), are presented as a function of MWCNT-TiO₂ annealing temperature and Bi₂S₃ deposition time. Random matrices of multiwall carbon nanotubes were grown on stainless steel substrates by spray pyrolysis and then functionalized with a thin layer of TiO₂. Air annealing modifies the morphology and C/TiO₂ ratio in the hybrid materials, from MWCNT-TiO₂ core and shell structures at 400 °C to carbon-doped TiO₂ (C-TiO₂) at 550 °C. Both matrices increase the amount of Bi₂S₃ deposited by the chemical bath, but the best photoelectrochemical performance is observed in electrodes based on C-TiO₂. Electrodes based on core–shell structures of MWCNT-TiO₂ show large capacitive currents that interfere with photocurrent generation, demonstrating the storage potential of MWCNT and the critical role of MWCNT/TiO₂ ratio for photoelectrochemical applications. Regardless of the superior properties of C-TiO₂ photoanodes, the power conversion efficiency of Bi₂S₃-sensitized C-TiO₂ is limited by the appearance of an electron collection barrier at the substrate/film interface.     

Achieving ultra-low friction of a-C:H film grown on 9Cr18Mo steel for industrial application via programmable high power pulse magnetron sputtering

Owing to the high hardness and hydrogen passivation of carbon bonds, hydrogenated diamond-like carbon (a-C:H) film has shown promising potential to achieve ultra-low friction and wear on steel surfaces. Here, a-C:H film was successfully deposited on 9Cr18Mo steel via programmable high power pulse magnetron sputtering and potential application for industrial was evaluated. The a-C:H films against different mating materials of GCr15 steel balls, Al₂O₃, Si₃N₄, ZrO₂, and a-C:H-coated GCr15 balls all showed ultra-low friction under a normal load of 5 N in a dry ambient air environment. Among them, self-mating tribo-system a-C:H films on steel surfaces and a-C:H-coated steel balls achieve best friction performance; the principal reason is that both contacting surfaces coated with a-C:H film have the lower electron affinities compared with other tribo-systems. However, the differences of coefficient of friction (COF) for uncoated-GCr15, Al₂O₃, ZrO₂, Si₃N₄, and a-C:H(GCr15) balls can be attributed to different sizes of clustering in wear debris. This work provides new insights on synthesis and industry application of the a-C:H films with ultra-low friction properties.     

Synthesis of Nanocrystalline Zr3N4 and Hf3N4 Powders from Metal Dialkylamides

A simple process to synthesize Zr₃N₄ and nitrogen‐rich Hf₃N₄ powders via ammonolysis of metal dialkylamides, i.e. Zr(NEt₂)₄ and Hf(NEt₂)₄, at temperatures below 700 °C is presented. The obtained nitrides have a rhombohedrally distorted NaCl‐type structure, which has previously been reported only for nitrogen‐rich films of these nitrides. Regardless of the atmosphere (N₂ and He), the Zr₃N₄ starts to decompose above about ～ 650 °C and achieves the highest decomposition rate at about 900 °C, finally yielding the mononitride ZrN. Both Zr₃N₄ and Hf₃N₄ powders are nanocrystalline with the crystal size of about 2 nm.     

Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release

The spatial distribution of Ce³⁺ and Ce⁴⁺ in each particle of Ce₂Zr₂O_x in a three‐way conversion catalyst system was successfully imaged during an oxygen storage/release cycle by scanning X‐ray absorption fine structure (XAFS) using hard X‐ray nanobeams. For the first time, nano‐XAFS imaging visualized and identified the modes of non‐uniform oxygen diffusion from the interface of Pt catalyst and Ce₂Zr₂O_x support and the active parts in individual catalyst particles.