工业VO2薄膜的电阻突变及其稳定性

以工业V2O5为原料，采用热分解法和还原法制备工业VO2薄膜。研究了制备工艺参数对电阻突变的影响及其在自然放置条件下的稳定性。结果表明：1）VO2薄膜的电阻突变达到了2．0－3.4个数量级，突变温度约为35℃，比纯VO2薄膜突变温度约低33℃；2)石英玻璃上的VO2薄膜的电阻突变数量级比普通玻璃上的大；3)H2还原法制备的VO2薄膜电阻突变数量级比N2热分解法制备的大；4)在自然放置条件下短时间内VO2薄膜可承受连续、反复多次的电阻突变，其突变数量级降低不多，突变温度滞后几乎没有变化；5)同等条件下石英玻璃上的VO2薄膜的电阻突变数量级降低较小、稳定性较好。     

Photocatalytic degradation of phenol in aqueous solution using TiO_2/Ti thin film photocatalyst

1　INTRODUCTIONHeterogeneousphotocatalysishasbeenwidelyin vestigatedasanalternativemethodfordegradationoforganicpollutantsinrecent 2 0 years .TiO2 isthemostinvestigatedphotocatalystuptodatebecauseitisoftenusedinthetreatmentofpollutantchemicals ,basedonitsremarkableactivity ,chemicalstability ,andalsoonitsnon toxicproperties.Phenolor phenoliccompoundsexistwidelyindailylifeandinindustrialwastewateroriginatingfromcokeovens ,petroleummanufactureorpaintstrippingoperations ,andhavebecomecommonp…     

Preparation and photocatalytic activity of PANI/TiO2 composite film

1. Introduction As an advanced oxidation technique (AOT), photocatalytic oxidation of semiconductor nanopar-ticles has been widely investigated by several groups during the past two decades [1-2]. Among all types of oxide semiconductor photocatalysts, nano-TiO2 is a very important photocatalyst for its strong oxidiz-ing power, nontoxicity, and long-term photostability [3]. Some researchers have reviewed the photocata-lytic mechanism of nano-TiO2 [4-5]. Generally, when the surface of TiO2 i…     

Interposition fixing structure of TiO2 film deposited on activated carbon fibers

1 Introduction Immobilization of TiO2 film on a substrate is necessary for its applications as TiO2 suspensions have fatal limitations in difficult separation and filtration for its reuse[1]. Thus, the fixing stability of TiO2 film with its substrate is …     

富钛的TiNi记忆合金薄膜组织结构

探讨了用ＨＣＤ法在玻璃基板上制备的Ｔｉ－４３．２７％Ｎｉ形状记忆合金薄膜和经不同热处理后的组织结构,结果表明,当镀膜的基板温度较高时,所得的薄膜基本晶化,其组织为由马氏体、Ｒ相、母相和Ｔｉ２Ｎｉ析出相等组成的多晶体。经热处理后,母相量增加,马氏体量减少,表明热处理使Ｍｓ点下降,利用这一现象,可扩大记忆合金薄膜的旷工 由曙加热到１１０℃的动态观察中发现,多晶体中的马氏休逐步缩小,消失,转变成母相、Ｒ     

Magnetoresistivity of DyNi2B2C thin film

We present high-resolution resistivity and magnetoresistivity measurements on a DyNi₂B₂C thin film obtained by laser ablation. The measurements are interpreted in the framework of the theory developed by Yamada and Takada (YT) in the early 1970s (Yamada H., Takada S. Prog Theor Phys 1973;49:1401) for the magnetoresistivity of the antiferromagnetic materials and permit identification of the magnetic field H_c2 that destroys the magnetic ordering. So, we obtain a H–T phase diagram where the antiferromagnetic and paramagnetic states are unambiguously determined and that we compare with data in the literature. Finally, in the paramagnetic state we have found a linear dependence between magnetoresistivity and the square of the magnetization.     

Soft-chemical synthesis and high-temperature electrochemical characteristics of VO2

1 Introduction In 1986, LVO (lithiated vanadium oxide) was first presented by FAUL et al[1?3] as positive electrode materials for thermal battery, which is a mixture of γ-LiV2O5 and VO2, but the morphology and crystallography of VO2 in the mixture were …     

ZrO_2／TiO_2复合光催化膜的微弧氧化法制备及表征

采用微弧氧化方法和原位生成的Zr（OH）_4胶体颗粒,在纯钛基体上制备ZrO_2／TiO_2复合光催化膜。采用SEM、EDX、XRD、UV-VisDRS等分析手段,对膜层进行分析表征。结果表明：复合膜显示出层状和多孔的结构,由锐钛矿、金红石和ZrO_2组成;相对于纯TiO_2膜,复合膜层的光吸收截止边缘产生红移;ZnO_2／TiO_2复合膜层和纯TiO_2膜层在紫外光照射下,对罗丹明B的光催化速率常数分别为0．0442和0．0186h~（-1）。     

Growth of epitaxial pyrite (FeS2) thin films using sequential evaporation

Pyrite (FeS₂), a semiconductor composed of inexpensive, non-toxic elements, has a band gap of ～0.95 eV and an absorption coefficient higher than conventional direct band gap semiconductors, including GaAs. These facts have inspired the use of pyrite as a potential candidate for terawatt-scale photovoltaic systems. However, there has been limited progress synthesizing thin films of sufficient quality to produce efficient solar cells. Here we describe the layer-by-layer growth of stoichiometric, single-phase pyrite thin films on heated substrates using sequential evaporation of Fe under high vacuum followed by sulfidation at pressures ranging from 1 mTorr to 1 Torr. High-resolution transmission electron microscopy reveals high-quality, defect-free pyrite grains. We demonstrate that epitaxial pyrite layers can be deposited with this method on natural pyrite substrates.     

Photocatalytic performance of TiO_2 immobilized on polystyrene (PS) thin film for mineralization of pollutants

A new photocatalyst, TiO2 powder immobilized on polystyrene (PS) thin films, was prepared using a novel method and its photocatalytic activity on the photodegradation of acridine dye in aqueous solution was tested. By this method, the crystal form and grain size of the immobilized TiO2 were well maintained. Compared with TiO2 powder, the photocatalytic activity of TiO2/PS thin films was not significantly reduced. The catalyst is stable and can be reused several times without the loss of activity, which makes wastewater treatment using this photocatalytic degradation technique of this way possible in the practical application.     

溶胶——凝胶工艺制备的TiO2纳米薄膜及其表面结构

采用溶胶—凝胶工艺在玻璃表面制备了均匀透明的锐钛矿型ＴｉＯ２ 纳米薄膜, 其颗粒大小在４０ ～８０ ｎｍ 。薄膜的Ｘ 射线衍射分析表明, 当薄膜的厚度小于０ ．４５ μｍ 时, 薄膜中未出现明显的锐钛矿的衍射峰。Ｘ 射线光电子能谱（ＸＰＳ） 和电子自旋共振谱（ＥＳＲ） 的实验结果表明： 薄膜中除含有Ｔｉ, Ｏ 元素外, 还有一定量的来自有机前驱物中未完全燃烧的碳和少量从玻璃表面扩散到薄膜中的Ｎａ 和Ｃａ 元素; Ｔｉ 元素除了以＋ ４ 价形式存在外, 还有一定量的Ｔｉ 以＋ ３ 和＋ ２ 价形式存在。ＴｉＯ２ 薄膜在５３０ ｎｍ附近的宽吸收带也证实了ＴｉＯ２ 薄膜中低价钛元素的存在。     

热处理对TiO2-V2O5纳米复合薄膜结构及性能的影响

以钛酸丁脂、V2O5粉末为前驱体,采用溶胶-凝胶技术制备了TO2-V2O5纳米复合薄膜,并通过椭偏仪、AFM、XRD、TG-DSC和UV-VIS-NIR分光光度计等方法研究热处理对复合薄膜特性的影响.结果表明:随热处理温度的升高,TiO2的结构由非晶到锐钛矿再到金红石相转变,并且金红石相出现和完全转变的温度降低约200℃;晶粒尺寸从5.1 nm逐渐增大227.3 nm;复合薄膜的折射率由1.6增大到2.4,同时薄膜厚度从276 nm降低到187 nm;薄膜在紫外光区的透射率减小,吸收边缘出现红移.     

Influences on photovoltage performance by interfacial modification of FTO/mesoporous TiO2 using ZnO and TiO2 as the compact film

An effective ZnO compact film (ZCF) has been introduced at the interface of fluorine doped tin oxide (FTO) substrate and mesoporous TiO₂ layer, and its effect on dye-sensitized solar cells (DSSCs) has been compared to that of conventional TiO₂ compact film (TCF). The ZCF and TCF prepared by spin-coating method on FTO are characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV–vis spectrophotometer. The existence of TiO₂ can suppress the recombination occurring at the interface of FTO/electrolyte, resulting in a higher J_sc and V_oc than bare FTO. The ZCF creates an energy barrier between FTO substrate and mesoporous TiO₂ layer, which not only reduces the electron back transfer from FTO to I₃^? in the electrolyte, but also leads to the accumulation of photogenerated electrons, and increases the electron density in the conduction band of TiO₂. The device based on FTO/ZCF substrate remarkably improves V_oc and FF, finally increases energy conversion efficiency by 13.1% compared to the device based on bare FTO and 4.7% compared to the counterpart based on FTO/TCF.     

Influence of cerium ions on the anatase-rutile phase transition of TiO2 prepared by sol-gel auto-igniting synthesis

The anatase-rutile phase transformation of TiO2 doped cerium up to 5 mol% was studied by X-ray diffraction and X-ray photoelectron spectroscopy. The samples were prepared by sol-gel auto-igniting synthesis process from a TiO(NO3)E-Ce(NO3)E-NH4NOE-citric acid complex compound system. The combusted amorphous powders were calcined at different temperatures. Significant structural changes were observed during the various stages of the phase transformation. It was concluded that at low dopant contents, cerium ions were incorporated into the TiO2 structure, and the anatase phase was stabilized; but at larger amounts, part of the dopant was segregated on the surface of TiO2 and the rutile formation was accelerated at elevated calcination temperature.     

Ba3YB3O9: phase transition and crystal structure

A new modification of the compound Ba₃YB₃O₉, β phase, has been attained through solid phase transition from phase at 1125–1134 °C. β-Ba₃YB₃O₉ crystallizes in the hexagonal space group with cell parameters a=13.0529(8) Å, c=9.5359(9) Å. The crystal structure of -Ba₃YB₃O₉ has been determined from powder X-ray diffraction (XRD) data. The refinement was carried out using the Rietveld methods and the final refinement converged with R_p=8.8%, and R_wp=11.8% with R_exp=5.65%. In its structure, the isolated [BO₃]³⁻ anionic groups are parallel to each other and distributed layer upon layer along the c-axis. The Y atoms are six-coordinated by the O atoms to form octahedra. The result of IR spectrum confirmed the existence of [BO₃]³⁻ triangular groups.     

Ag改性TiO2／SnO2纳米薄膜及光催化降解甲基橙的性能

以光还原沉积法对TiO2/SnO2薄膜进行Ag改性,制备Ag-TiO2/SnO2纳米薄膜,讨论紫外光照时间、光照强度、AgNjO3浓度等工艺条件埘光催化活性的影响.用XRD和SEM对薄膜的结构、表面形貌和化学组成进行表征,以甲基橙为模拟污染物对光催化性能进行测定.结果表明:在最佳条件下制备的Ag-TiO2/SnO2薄膜,Ag担载量为0.51%(摩尔分数),Ag簇直径在30～90 nm之间:薄膜具有较高的光催化活性,对甲基橙的降解率是修饰前TiO2/SnO2薄膜的2.02倍,是相同质量TiO2/ITO薄膜的3.30倍;催化活性的提高,源于反应机理的改变:薄膜中Ag-TiO2异质结的引入,一方面进一步促使光生电荷的分离,另一方面加速了氧气与激发电子的还原反应.     

Properties of TiO2 film prepared from titanium tetrachloride

The properties of TiO₂ film prepared by titanium tetrachloride were investigated with respect to annealing temperatures in terms of phase change, crystallite size, and band gap energy. The TiO₂ film dried at room temperature exhibited an amorphous phase, while films calcined above 281 and at 990°C displayed anatase TiO₂ and a mixture of anatase and rutile, respectively. The TiO₂ film was transformed to an anatase phase through three stages during the annealing processes: (1) removal of water, (2) decomposition of a peroxo group, and (3) amorphous-anatase phase transformation. It was also found that the bandgap energy of TiO₂ film was changed with increasing annealing temperature. This is attributed to the quantum size effect in the range of 475–675°C and to the formation of rutile phase having lower band gap energy than anatase in the range of 675–990°C.     

ZrW2O8薄膜的制备及热膨胀性质

采用溶胶-凝胶技术结合退火工艺在Pt(111)/Ti/SiO2/Si(100)基片上制备ZrW2O8薄膜,并研究了退火温度、退火时间对薄膜的影响.利用X射线衍射(XRD)及扫描电镜(SEM)对薄膜的物相及表面形貌进行表征;利用变温XRD研究薄膜的热膨胀性能.薄膜的变温XRD结果表明,在室温～700℃温度范围内,随着温度的升高,(211)和(310)晶面间距变小,其热膨胀系数为负值,而(332)晶面间距随温度升高变大,显示出正膨胀性质.这表明ZrW2O8薄膜材料的热膨胀性能是各向异性的.     

Nano-tribological characteristics of PZT thin film investigated by atomic force microscopy

In this work, the nano-scale tribological characteristics of PZT thin films (Pb(Zr_xTi_1 − x)O₃: PZT) with various Zr/Ti ratios were investigated using an Atomic Force Microscope (AFM). The PZT thin films deposited by the sol-gel method were characterized by using an AFM, X-Ray Diffraction (XRD), and a nano-indentation technique. From the experimental results, the friction coefficient of the PZT thin film was found to be about 0.1-0.2 under a 0.1-10 μN normal force. It was determined that the wear rate of the PZT thin film was in the order of 10^− 8 mm³/N·cycle. Also, it was observed that the crystalline structure of the PZT was amorphized due to mechanical stress.