热处理条件和Y掺杂对VO2粉体结构及相变温度的影响(英文)

以水热合成法制备VO₂粉体,研究热处理条件和Y掺杂对VO₂结构及相变温度的影响。XRD、SEM和TEM结果表明:热处理温度对VO₂前驱体的晶型转变影响显著,升高温度,有助于VO₂(B)向VO₂(M)转变。Y掺杂对VO₂结构产生影响,Y³⁺可以占据V⁴⁺晶格点阵位置,形成YVO₄固溶体,从而增大VO₂的晶胞参数。Y掺杂导致的晶格变形能阻止颗粒的聚集,因此,Y掺杂具有一定的细化晶粒作用。DSC曲线表明,Y掺杂可以降低VO₂(M)的相变温度,当Y掺杂浓度为9%(摩尔分数)时,相变温度可由未掺杂的68.3℃降低到61.3℃。     

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…     

Structural, electrical and mechanical properties of magnetron sputtered NiTi/PZT/TiOx thin film heterostructures

Shape memory alloy (NiTi) thin films coupled to ferroelectric lead zirconate titanate (PZT) produce an intelligent material capable of performing both sensing and actuating functions. In the present study, we report on the in-situ growth of NiTi/PZT/TiO_x heterostructure on Pt/Ti/SiO₂/Si substrates using magnetron sputtering technique. Deposition processing, microstructure, surface morphology, electrical properties and mechanical properties of these heterostructures were systematically investigated. The top NiTi films exhibit austenitic B2 structure with preferred (110) orientation. The varying thickness of NiTi films had a significant influence on properties of NiTi/PZT/TiO_x heterostructure. The bottom TiO_x layer was observed to favor the growth of perovskite PZT films with (100) orientation. Nanoindentation tests of these heterostructures were performed at room temperature. The mechanical hardness of the top NiTi layer of lower thickness was found to be highly influenced by underneath PZT layer. The heterostructure exhibited an interesting martensite to austenite phase transformation and polarization-electric field hysteresis behavior with remanent polarization (P_r) and the coercive field (E_r) of 17.1 μC/cm² and 69.6 kV/cm, respectively. These heterostructures having a layer of SMA material coupled to a ferroelectric material with underneath TiO_x layer are of immense technological importance for MEMS devices.     

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…     

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     

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 …     

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.     

Effect of Nb doping on the phase transition and optical properties of sol-gel TiO2 thin films

Various content Nb-doped TiO₂ thin films were prepared by sol-gel process. XRD analysis shows that the existence of crystalline TiO₂ in anatase and rutile form depends on the Nb content in the examined samples. It is observed that Nb promotes the anatase to rutile phase transition but has a depression effect on the anatase grain growth. It is found that incorporation of about 4 at.% of Nb completely transforms anatase TiO₂ to the rutile form at a calcination temperature as high as 900 °C. The mechanism is proposed. Optical analyses show that the films have an average of 60% transmission in visible region. The energy gap values using Tauc's formula have also been estimated. The band gap of rutile Ti_1−xNb_xO₂ solid solutions increases with increasing x.     

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 …     

二氧化钒纳米点阵的制备及其红外光学特性研究

为了得到相变温度低且变色性能优越的光学材料,使其能够广泛应用于智能窗领域,对周期结构VO2纳米点阵的相变和光学特性展开了研究。用修正的Sellmeier色散模型结合二维点阵周期结构的等效折射率计算了VO2纳米点阵在不同占空比下的反射率和透射率。利用多孔氧化铝模板掩膜溅射法,先在玻璃上制备钒金属纳米点阵,再经热氧化工艺制备出VO2纳米点阵,测试其表面形貌、组分结构、红外反射和透射谱线。结果表明,占空比为0.83的纳米点阵其相变温度有效降低至43℃,在1700 nm处透射率改变量达到29%,表现出良好的变色特性,且透射率整体高于VO2薄膜。说明通过制备较佳占空比的纳米点阵可以有效降低材料的相变温度,提升材料的热致变色性能。     

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.     

磁控溅射TiO2薄膜的相结构转变温度

利用射频磁控溅射制备了TiO2致密薄膜,并通过退火处理实现TiO2的相转变,采用扫描电镜,X射线衍射等手段对薄膜相结构进行表征并做了详细的分析,结果表明,退火后TiO2薄膜结构致密,表面呈现出大小均匀的纳米晶粒。400 ℃退火时,TiO2薄膜为单一的锐钛矿相,500～600 ℃退火时为锐钛矿和金红石混合相,700 ℃以上退火时则完全转变为金红石相。     

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。     

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.     

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.     

铬过渡层对氮化铬/镁合金膜基界面结合强度的影响

为了提高磁控溅射氮化铬膜与镁合金基底的结合强度,在两者之间以不同工艺溅射沉积铬过渡层,分析并讨论了铬过渡层对膜基界面结合强度的影响及其机制.结果表明,在镁合金/氮化铬之间增加铬过渡层可提高表征膜基结合强度的膜层破裂临界载荷,且当铬过渡层的溅射工艺为溅射功率100 W、负偏压30 V、基底温度25℃、溅射时间4 min时...     

微球结构MoS2/FeS复合薄膜的制备及表征

采用离子注入结合低温离子渗硫法制备了MoS₂/FeS复合薄膜,并借助扫描电子显微镜、X射线光电子能谱仪和纳米压痕仪对复合薄膜进行了表征。结果表明,复合薄膜呈微球结构,颗粒尺寸均匀,约为500 nm。复合薄膜主要由MoS₂、FeS及少量的氧化物组成。基体与复合薄膜的硬度分别为6.57和7.89 GPa,弹性模量分别为223.8和246.2 GPa。相对基体复合薄膜的硬度及弹性模量分别提高约20%和10%,弹性特征值H/E亦相应提高了约10%,表明其较基体具有更高的磨损抗力。