溶胶-凝胶法制备WO3电色薄膜

采用溶胶-凝胶法以钨粉过氧化聚钨酸的有机溶液为先驱物制备出了WO3薄膜,研究了添加无水乙醇、冰乙酸对其成膜性能的影响,并进行了厚度、可见光谱、电化学循环伏安、X-射线测试.结果表明该法能制得质量好的WO3非晶态薄膜.     

玻璃用WO3基电致变色材料的研究

电致变色玻璃是电致变色材料最典型的应用,WO_3是一种发现得较早、研究较为深入、应用最为广泛的阴极电致变色材料,本文介绍了电致变色材料的分类,并从WO3基电致变色薄膜和WO_3薄膜的制备两个方面对WO3基电致变色材料进行了研究。     

工艺参数对磁控溅射WO_3薄膜电致变色性能的影响

本文采用磁控溅射法制备了用于电致变色器件的WO_3薄膜,用X射线衍射仪(XRD)、场发射扫描电镜(FE-SEM)、紫外-可见分光光度计(UV-Vis)对其物相组成、微观形貌以及电致变色性能进行了表征。结果表明:在溅射压强为2 Pa、氩氧比为60:20时所制备的WO_3薄膜厚度适中,且有利于离子的嵌入/脱出,而以此薄膜制备的电致变色器件光调制范围最大,褪色时间最短,着色效率达82.9 cm~2/C。     

溶胶—凝胶法制备WO3—MoO3电致变色膜的性能

利用自动分光光度计分析、差热分析、热失重分析、电化学循环伏安分析、红外光谱分析、Ｘ射线法射分析等技术,详细研究了氧化钼的引入对氧化钨溶胶－凝胶转变及氧化钨电变色性能的影响,指出氧化钼可有效地稳定氧化钨溶液,同时也使氧化钨薄膜的着色效率提高,褪色效率下降。     

Effects of casting and post casting annealing on xylene isomer transport properties of Torlon 4000T films

Procedures for Torlon^® 4000T membrane formation were developed to provide attractive and repeatable xylene separation properties. Torlon^® 4000T membrane films cast by our method were investigated in terms of thermally induced imidization, molecular weight enhancement, and solvent removal. After development of the Torlon^® 4000T casting procedure, pervaporation of a xylene mixture (i.e. 30% para-xylene, 30% meta-xylene, 30% ortho-xylene, and 10% ethylbenzene) was performed in both Torlon^® 4000T and post casting annealed Torlon^® 4000T films. The xylene pervaporation in annealed Torlon^® 4000T film at 200 °C gave a permeability of 0.25 Barrer and a selectivity of 3.1 (para/ortho) and 2.1 (para/meta) respectively. A so-called “permeability collapse” reflecting an accelerated reduction in the free volume is consistent with significant temperature-induced changes in the films observed after thermal annealing at 300 °C. This conditioning effect is induced by a combination of heat treatment and the presence of the interacting aromatic penetrants. Optical methods were used to verify that the density of annealed samples exposed to xylene for 5 days eventually increased, suggesting that the membrane is originally swollen upon initial xylene exposure, and then relaxes to a more densified, and more discriminating state.     

基于溶胶凝胶法制备WO3电致变色膜的溶胶特性研究

WO3是用于电致变色玻璃的阴极电致变色材料之一,采用溶胶凝胶法制备WO3薄膜具有设备简单、成本低、适合大面积制膜等特点,WO3溶胶的稳定性是一个值得深入研究的课题.采用过氧化聚钨酸法制备WO3溶胶,主要考察了钨粉-H2O2反应温度、过氧聚钨酸-乙醇反应温度、钨粉和H2O2配比等因素对溶胶稳定性的影响.研究结果表明:钨粉和H2O2反应在冰水浴中进行时控制温度在8℃以下可避免白色沉淀物过多产生.当钨粉与H2O2摩尔比为1∶7,过氧聚钨酸-乙醇反应温度为45～ 50℃,并再在80℃浓缩后可以得到稳定性和成膜性好的透明的橘黄色溶胶.     

Epitaxial Bi5Ti3FeO15 thin films on Nb-doped SrTiO3 substrates

We investigated the ferroelectric switching dynamics as well as the multiferroic and piezoelectric properties of highly a-oriented epitaxial Bi₅Ti₃FeO₁₅ (BTFO) thin films on Nb-doped SrTiO₃ single crystal substrates. The BTFO thin films favored highly a-oriented crystallinity because c-oriented crystallinity decreased under deposition conditions in which substrate temperature and thin film deposition rate were simultaneously lowered. The highly a-oriented epitaxial BTFO thin films showed the best ferroelectric properties, whereas the highly c-oriented epitaxial BTFO thin films showed the best ferromagnetic properties. In particular, the BTFO thin films in which a- and c-oriented crystallinity were properly mixed showed the best piezoelectric properties.     

纳米氧化钨薄膜的制备方法及其性质研究

综述了纳米氧化钨薄膜的各种制备方法：溶胶-凝胶法、溅射法、蒸发法、化学气相沉积法、阳极氧化法等，并比较了其优缺点；介绍了氧化钨薄膜的掺杂研究；对纳米氧化钨薄膜的电致变色、气敏特性等性质研究现状作了简要概述，提出了纳米氧化钨薄膜的发展前景。     

Effects of post-deposition annealing on different DLC films

Amorphous hydrogenated carbon films have been deposited by plasma-enhanced chemical vapour deposition at different process pressures and substrate temperatures, resulting in film properties ranging from polymer-like to diamond-like. The deposition parameter combinations were chosen by experimental design to enable the determination of both deposition pressure and deposition temperature effects on the annealing behaviour. The deposited films have then been annealed in vacuum at successively higher temperatures. Changes in optical band gap, internal stress, film thickness and infrared (IR) absorption spectra have been recorded to assess the influence of deposition parameters on the thermal stability of diamond-like carbon (DLC) and to identify temperature-induced modifications in the bonding structure. The results show a large variation in thermal stability between the different DLC films; samples deposited at low pressure display the greatest stability. The internal stress of the films starts decreasing at very low annealing temperature (<100 °C for the majority of samples), in most cases long before any decrease in the optical band gap can be detected. This is explained by a movement of hydrogen from sp² to sp³ sites as detected by IR measurements.     

Effect of post annealing treatment on electrochromic properties of spray deposited niobium oxide thin films

Niobium oxide thin films were deposited on the glass and fluorine doped tin oxide (FTO) coated glass substrates using simple and inexpensive spray pyrolysis technique. During deposition of the films various process parameters like nozzle to substrate distance, spray rate, concentration of sprayed solution were optimized to obtain well adherent and transparent films. The films prepared were further annealed and effect of post annealing on the structural, morphological, optical and electrochromic properties was studied. Structural and morphological characterizations of the films were carried out using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques. Electrochemical properties of the niobium oxide thin films were studied by using cyclic-voltammetry, chronoamperometry and chronocoulometry.     

Synthesis of WO3 thin films by surfactant mediated spray pyrolysis

WO₃ thin films were prepared by surfactant mediated spray pyrolysis deposition on fluorine-doped tin oxide (FTO) conductive glass using hexadecylthymethylammonium bromide (HTAB) as structure-directing agent. The crystalline structure, topography, electrical conductivity and optical properties were investigated as function of cationic surfactant concentration. High transparency and conductivity were obtained for the sample which contained the lowest amount of surfactant (50 ppm) in the spraying solution. Significant changes in the morphology were observed with increasing HTAB addition level; samples lost their homogeneity and porosity, while the layer roughness increased. The surfactant by-products resulted after annealing were investigated based on FTIR analysis and a decomposition scheme was proposed. The modified surface composition and morphology influenced the hydrophilic character of the samples.     

磁控溅射制备非晶态WO_3薄膜的光催化性能

采用射频反应磁控溅射工艺在玻璃基片上沉积了非晶态WO3薄膜。通过光催化降解亚甲基蓝和罗丹明B溶液实验,研究了所制WO3薄膜的光催化活性和使用寿命。X射线衍射(XRD)分析表明:所制备的WO3薄膜为非晶态。光催化实验表明:紫外光照3h后,薄膜对亚甲基蓝和罗丹明B溶液的最大降解率分别为83.26%和72.73%。重复使用3次后,薄膜对亚甲基蓝的降解率保持在75%以上,7次使用后薄膜基本丧失光催化活性。采用去离子水超声处理30min的方法可使已失活薄膜对亚甲基蓝的降解率从20%恢复至81%。     

非晶态TiO2/WO3光催化复合薄膜的失活与再生

研究了非晶态TiO2/WO3薄膜降解亚甲基蓝的光催化活性、失活及活性再生等问题。在本实验条件下,新制非晶态TiO2/WO3薄膜对亚甲基蓝的降解率为93.8%。试验表明,使用6次后其对亚甲基蓝的降解率仍可达85%以上,经10次使用后薄膜基本丧失光催化活性。对于失活的光催化薄膜,分别采用（a）蒸馏水浸泡30 min、（b）乙醇浸泡30 min、（c）蒸馏水超声处理30 min、（d）乙醇中超声处理30 min对其进行活性再生实验。上述4种方法可将使用9次后的光催化膜对亚甲基蓝的降解率从10.3%分别恢复至23.2%、28.3%、79.2%、90.5%。     

Effects of the annealing atmosphere on the microstructure and properties of BiFe0.99Zn0.01O3 films

BiFe_0.99Zn_0.01O₃ (BFZO) films were annealed in different atmospheres (Air, N₂ and O₂) on ITO/glass substrates. The influences of the different annealing atmospheres on the oxygen vacancy concentration, microstructure, ferroelectric behavior, leakage current, leakage mechanism, aging and dielectric performance of the BFZO films were studied. The crystallization and grain development for the sample annealed in an O₂ atmosphere improved, and the concentrations of the Fe²⁺ and oxygen vacancies were the lowest among the samples studied herein. The BFZO film had the lowest leakage current density and the best ferroelectric performance in an O₂ annealing atmosphere among the samples studied herein, and the leakage was due to the F-N tunneling effect mechanism. From the perspective of the volume effect, the aging model was established, and the aging mechanism of the BFZO films was discussed in depth. Compared with Air and N₂, the annealed film in O₂ exhibited no obvious aging.     

Kinetics of coloration of anodic electrochromic films of WO3·H2O

Polycrystalline layers of WO₃·H₂O are obtained by anodization of tungsten in 1 N H₂SO₄ at 70° C. The cathodic reduction of these layers in acid solutions causes the formation of blue WO_3–x·H₂O (0相似文献   

Effects of annealing on low dielectric constant carbon doped silicon oxide films

Dielectric materials with lower permittivity (low k) are required for isolation to reduce the interconnect RC delay in deep submicron integrated circuit. In this work, carbon doped silicon oxide [SiO(C–H)] films are investigated as a potential low k material. The films were prepared by the radio frequency plasma enhanced chemical vapor deposition (PECVD) technique from trimethylsilane (C₃H₁₀Si or 3MS) in an oxygen (O₂) environment. SiO(C–H) films deposited with O₂ and 3MS flow rates of 100 sccm and 600 sccm, respectively have been previously found to produce dielectric constant as low as 2.9. This is attributed to the incorporation of carbon in the form of Si–CH₃ bond, which has lower polarizability compared to the Si–O bonds that were replaced. In this work, these low k films were annealed at 400, 500, 600 and 700 °C in a N₂ atmosphere for 30 min to determine the thermal stability of their properties. The films were characterized in terms of their thickness shrinkage, refractive indices, dielectric constants, infrared absorption, surface morphology and stress upon annealing. For annealing temperatures up to 500 °C, which is beyond the current highest processing temperature for back end of the line structure of around 450 °C, a slight decrease in the refractive indices and dielectric constants of the films are observed. The SiO(C–H) films also remain smooth and exhibit tensile stress with stress level that is within practical acceptable range. The results suggest that the SiO(C–H) films are thermally stable to be applied as low dielectric constant materials for deep submicron integrated circuit.     

Heat treatment of amorphous electrochromic WO3 thin films deposited onto indium-tin oxide substrates

Electrochromic tungsten oxide thin films, obtained by vacuum evaporation, were studied before and after heat treatment between 25 and 250°C for 2 h in air. Electrochromic properties were investigated in acid electrolyte by simultaneous measurements of the electrical and optical parameters. A.c. complex impedance techniques and voltammetry were used to characterize the films from an electrical point of view. We observed an enhancement of the electrochromic response times during both coloration and bleaching after heat treatment carried out between 150 and 220°C. This phenomenon was associated with a decrease of the ohmic drop in the electrode and a continuous variation of the impedance diagrams of these electrochromic electrodes. Moreover, we observed that the diffusion coefficient of H⁺ ions into WO₃, obtained on colored thin films, increased as the electrochromic kinetics increased.     

Oxygen vacancy enhanced room temperature ferromagnetism in Ar+ ion irradiated WO3 films

Room-temperature ferromagnetism in WO₃ films was enhanced by 130 keV Ar⁺ ion irradiation. The X-ray diffraction (XRD) and Raman measurements not only confirmed the monoclinic phase of the irradiated WO₃ films, but also showed that oxygen vacancy (V_O) defects were formed. The analysis of photoluminescence spectra strongly reconfirmed the presence of oxygen vacancy. X-ray photoelectron spectroscopy (XPS) measurements revealed that the contents of V_O and induced W⁵⁺ ions increase with increasing irradiation fluence and rich W⁵⁺-V_O defect complexes in the irradiated WO₃ films were formed. Further, the magnetic measurements exhibited a 2-fold enhancement in the saturation magnetization at the largest fluence of 3 × 10¹⁶ ions/cm². At lower irradiation fluence, a bound magnetic polaron model was proposed to reveal the ferromagnetic exchange coupling resulting from overlapping of V_O⁺ and V_O⁺⁺ defect states, and 5d¹ states of W⁵⁺. At high irradiation fluence, the carrier concentration reaches 1.02 × 10²⁰/cm³ and carrier-mediated exchange interactions result in the film's ferromagnetism.     

Electrochromic features of hybrid films composed of polyaniline and metal hexacyanoferrate

Hybrid organic/inorganic films, composed of polyaniline (PANI) matrix and Prussian blue-like nickel hexacyanoferrate redox centers, showed reversible electrochromic behavior in acidic potassium salt electrolytes. The system's coloration properties were assessed from various spectroelectrochemical measurements including voltabsorptometry that involved monitoring of the time-derivative signal of absorbance at 700 and 410 nm as a function of linearly scanned potential. Gold-covered foil was used as a conductive, optically transparent, substrate onto which the composite film was electrodeposited by potential cycling in the mixture for modification consisting of aniline monomer, Ni²⁺, Fe(CN)₆³⁻ and electrolyte containing K⁺ and H⁺ ions. An important feature of hybrid (composite) material was that its electrochromic properties were dominated by color changes occurring in the PANI component. Coloration originating from nickel hexacyanoferrate barely affected the system's electrochromic characteristics. But the cyanometallate redox centers distributed in the PANI matrix behaved reversibly as expected for a system capable of fast charge transport.