Surface and interface characteristics of TiO2–muscovite nanocomposites

The morphology and chemical characteristics of the surface and the interface of TiO₂–muscovite nanocomposites were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Our results clearly showed that TiO₂ grains formed on the TiO₂ thin film surface, whereas the presence of TiO₂ grains on the interface between TiO₂ thin films and the muscovite substrates was not obvious. While euhedral rutile grains were found in samples doped with Zn ions, none were found in samples doped with Sn ions. The XPS results showed that cations present in the muscovite substrates diffused into the TiO₂ thin films. Etching measurements revealed that diffusion abilities of cation impurities varied: Si and Al diffused more easily than K. The observed differences in chemical composition and oxidation of the elements, especially on the surface and the subsurface, may influence the different crystallization behaviors of elements in TiO₂ thin films and the different active degree of elements diffusing from muscovite substrates.     

EFFECT OF THERMAL TREATMENTS ON THE SUPERCONDUCTIVITY OF UNDOPED AND WO3 DOPED Y-Ba-Cu-O SYSTEM

Undoped and WO₃-doped Y-Ba-Cu-O ceramics have been slowly cooled in flowing oxygen or quenched in air from 900℃ to room temperature, after sintering at 900℃ for 3Oh in flowing oxygen. The ac susceptibility measurements show that the T_c of the quenched WO₃-doped Y-Ba-Gu-O superconductor can reach 88K, while the undoped Y-Ba-Cu-O ceramic quenched in air is a non-superconductor. X-ray diffraction data show that WO₃ does not enter into the YBa₂Cu₃O_7-x lattice but forms all impurity phase. The WO₃-doped YBCO specimens quenched in air consist of orthorhombic YBa₂Cu₃O_7-x phase and an impurity phase which increases with increasing WO₃ content. Raman spectra chow that oxygen contents are different for undoped and WO₃-doped samples. It la suggested that suitable doping with WO₃ can change the oxygen content and reduce the effect of thermal treatments on the superconductivity of Y-Ba-Cu-O system.     

H_2气氛退火处理对Nb掺杂TiO_2薄膜光电性能的影响

采用电子束沉积方法,以钛酸锶(SrTiO3)为衬底制备铌(Nb)掺杂TiO2薄膜并研究后续H2气氛退火处理对其薄膜样品光电性能的影响.结果发现H2气氛热退火处理能有效改善Nb掺杂TiO2薄膜的导电率,最佳电阻率达到5.46×10-3Ω·cm,在可见光范围内的透光率为60%—80%.导电性能的改善与H2气氛退火处理后多晶薄膜的晶粒尺寸变大和大量的氧空位形成及H原子掺杂有关.     

旋涂法制备WO3薄膜电致变色性能

"智能窗"大规模推广顺应可持续发展潮流,三氧化钨(WO_3)是生产"智能窗"的一种重要电致变色材料,但调控WO_3薄膜电致变色性能机制仍待进一步研究。采用旋涂法制备WO_3薄膜,重点研究了溶液浓度和旋涂次数对调控WO_3薄膜电致变色性能的影响。通过表面轮廓仪测量薄膜厚度,X射线衍射(XRD)测量薄膜结晶情况,原子力显微镜(AFM)和扫描电子显微镜(SEM)分析薄膜表面形貌,光谱仪测量薄膜初始态、着色态和褪色态的透射率。实验结果表明,随着溶液浓度增加(0. 2～1. 0 mol/L),薄膜厚度从9. 7 nm增加到33. 3 nm,透射率调制能力从0%提升到37. 0%;多次旋涂薄膜厚度线性增长,线性拟合优度(R~2)达0. 98,5次旋涂后透射率调制能力达51. 3%。改变溶液浓度和旋涂次数都是调控薄膜透射率调制能力的有效手段,精准调控薄膜透射率调制能力对设计不同应用场景的电致变色器件具有重大意义。     

WO3/Pt复合薄膜的制备及其光电催化性能

导电玻璃作为基底水热法生长了WO₃纳米棒,通过电沉积法改变沉积Pt的时间(40 s,80 s,120 s),以WO₃纳米棒为基底沉积得到不同的WO₃/Pt复合薄膜样品。通过X射线衍射分析和扫描电子显微镜等测试手段将WO₃纳米棒薄膜和WO₃/Pt复合薄膜样品进行表征。结果表明成功制备了WO₃/Pt复合薄膜样品。漫反射结果显示WO₃/Pt复合薄膜与WO₃薄膜相比具有更强的光吸收。交流阻抗谱显示WO₃/Pt复合薄膜与WO₃纳米棒薄膜相比增强了电荷转移效率。利用光电流、光电催化对WO₃/Pt复合薄膜进行光电性能测试,结果表明WO₃/Pt复合薄膜相较于单一WO₃薄膜光电流活性更高和光电催化活性更强,并且沉积时间为80 s的WO₃/Pt复合薄膜显示最为优异的光电流和光电催化性能。同时,沉积时间为80 s的WO₃/Pt复合薄膜的光电催化性能优于其光催化和电催化性能。     

Cu掺杂SnO_2/TiO_2复合薄膜的制备及性能研究

制备Cu掺杂的纳米Sn O2/Ti O2溶胶,采用旋涂法在载玻片上镀膜,经干燥、煅烧制得Cu掺杂的Sn O2/Ti O2薄膜,通过对比实验探讨掺杂比例、条件、复合形式等对结构和性能的影响。采用XRD、SEM、EDS、UVVis等测试手段对样品进行表征,并以甲基橙为探针考察了其光催化降解性能。XRD测试结果显示薄膜的晶型为锐钛矿型,结晶度较高。SEM谱图显示薄膜表面无明显开裂,粒子分布均匀,粒径约为20 nm。EDS测试结果表明薄膜材料中含有Cu元素,谱形一致。UV-Vis吸收光谱表明Cu掺杂以及Sn O2/Ti O2的复合使得在近紫外区的光吸收比纯Ti O2明显增强。光催化实验表明Cu掺杂后使得Sn O2/Ti O2复合薄膜对甲基橙的光催化降解效率进一步提高,Sn O2/Ti O2复合薄膜的光催化活性在10%Cu掺杂时达到最高。     

钽掺杂二氧化钛薄膜的光电性能研究

采用脉冲激光沉积法 (PLD), 以石英玻璃为衬底制备了钽掺杂TiO₂薄膜并研究了薄膜样品的光电性质. 沉积氧气分气压从0.3 Pa变化到0.7 Pa时薄膜样品的帯隙变化范围是3.26 eV到3.49 eV. 通过测量电阻率随温度的变化关系确定了薄膜内部的主要导电机理. 在150 K到210 K温度范围内, 热激发导电机理是主要的导电机理; 而在10 K到150 K范围内; 电导率随温度的变化复合Mott的多级变程跳跃模型 (VRH); 在210 K到300 K范围内, 电阻率和exp(b/T)^1/2呈正比关系. 关键词： 2')" href="#">Ta掺杂TiO₂ 脉冲激光沉积法 薄膜 导电机理     

Formation of Ca-doped YBa2Cu4O8 phase in thin films

Ca-doped YBa₂Cu₄O₈ (124) thin films are prepared on (100) SrTiO₃ substrates by annealing the amorphous films deposited using a pulsed laser deposition technique. The X-ray diffraction measurements show that the Ca-doped YBa₂Cu₄O₈ phase is formed by annealing below 800°C at a oxygen pressure of 1 atm. The 124 films have c-axis orientation normal to the substrates. As the Ca content increases, the proportion of the 123 impurity phase in the samples increases. The onset temperature of superconductivity of the Y(Ca)Ba₂Cu₄O₈ films increases from 79 K to 88 K with an increase Ca-substitution for 5 to 10% of Y.     

The influence of different fabrication processes on characteristics of excess Bi2O3-doped 0.95 (Na0.5Bi0.5)TiO3–0.05 BaTiO3 ceramics

In this study, we will develop the influences of the excess x wt% (x=0, 1, 2, and 3) Bi₂O₃-doped and the different fabricating process on the sintering and dielectric characteristics of 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃ ferroelectric ceramics with the aid of SEM and X-ray diffraction patterns, and dielectric–temperature curves. The 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ ceramics are fabricated by two different processes. The first process is that (Na_0.5Bi_0.5)TiO₃ composition is calcined at 850 °C and BaTiO₃ composition is calcined at 1100 °C, then the calcined (Na_0.5Bi_0.5)TiO₃ and BaTiO₃ powders are mixed in according to 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ compositions. The second process is that the raw materials are mixed in accordance to the 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ compositions and then calcining at 900 °C. The sintering process is carried out in air for 2 h from 1120 to 1240 °C. After sintering, the effects of process parameters on the dielectric characteristics will be developed by the dielectric–temperature curves. Dielectric–temperature properties are also investigated at the temperatures of 30–350 °C and at the frequencies of 10 kHz–1 MHz.     

Growth mechanism and characterisation of chemically grown Sb doped Bi2Se3 thin films

The synthesis of combinatorial Bi_2−xSb_xSe₃ thin films by arrested precipitation technique (APT) using triethanolamine-bismuth, triethanolamine-antimony and sodium selenosulphite as sources of Bi³⁺, Sb³⁺ and Se²⁻, respectively is investigated on commercial glass substrates. The growth mechanism of film formation, composition and surface morphology of the as deposited films were studied as a function of preparative parameters and bath composition. The films were monophasic, polycrystalline and covered the surface of the substrate completely. Energy dispersive X-ray analysis gave coherent elemental composition indicating single phase BiSbSe₃ was made. The good results obtained for Bi_2−xSb_xSe₃ thin films revealed that arrested precipitation technique is best suited for the deposition of large area thin films on conducting/nonconducting substrates to produce materials for device applications.     

Cu掺杂纳米TiO2光催化还原CO2实验研究

利用溶胶凝胶法制备不同掺杂量的CuO-TiO₂纳米粉体,采用热重差热分析仪（TG-DTA）,X射线衍射仪（XRD）,场发射扫描电镜（FSEM-EDX）等手段对其进行表征;在波长为253.7nm的紫外灯照射下,进行CO₂光催化还原实验研究,探究CO₂光催化资源化利用可行性,。结果表明,溶胶凝胶法制备所得CuO掺杂TiO₂纳米粉体,粒径大小在20～30 nm之间;CO₂光催化还原主要产物为甲醇,掺杂量为5%（质量分数）CnO-TiO₂纳米粉体催化效果最好,反应10 h后得到甲醇产量为27mg·（g-cata）^-1;随着反应时间的增加,产物中甲醇含量也逐渐增加。     

Structural,Optical and Electrochromic Properties of WO_3 Thin Films Prepared by Chemical Spray Pyrolysis Versus Spin Coating Technique

In this study, Tungsten Oxide (WO₃) thin films were prepared by Chemical Spray Pyrolysis (CSP) and Spin Coating (SC) techniques and it was investigated effects of technique and parameter on the films. WO₃ thin films were deposited on ITO (Indium Tin Oxide) coated glasses. The structural, optical and electrochromic properties of the WO₃ thin films were characterized by XRD, SEM, UV, and CV measurements. The sharpest (200) peak was observed in the XRD spectra and optical band gaps were calculated around 2.6～3.1 eV via UV-Vis spectra for all of the samples. Micro fibrous reticulated surface (filamentous like) morphology for the films deposited by CSP technique and smooth surface morphology with high optical transmittance for the film deposited by SC Technique were obtained from SEM images. In addition to these results, it was revealed that all the samples exhibit good electrochromic performance.     

Influence of silver doping on the photocatalytic activity of titania films

By means of X-ray diffraction, BET nitrogen adsorption, UV-Vis-NIR transmission spectroscopy, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy and photodegradation of methylene blue, effects of Ag doping on the microstructure and photocatalytic activity of TiO₂ films prepared by sol–gel method were studied. It is found that with a suitable amount (2–4 mol%), the Ag dopant increases the photocatalytic activity of TiO₂ films. The mechanism can be attributed to that (1) anatase grain sizes decrease with Ag doping and the specific surface areas of doped TiO₂ films increase, the charge transfer in TiO₂ films is promoted; (2) by enhancing the electron–hole pairs separation and inhibiting their recombination, the Ag dopant enhances the charge pair separation efficiency for doped TiO₂ films.     

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO_2 thin films as efficient electron transport layer

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO_2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly(3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester(PCBM). 1% vanadium-doped TiO_2nanoparticles were synthesized via the solvothermal method. Crystalline structure, morphology, and optical properties of pure and vanadium-doped TiO_2 thin films were studied by different techniques such as x-ray diffraction, scanning electron microscopy, transmittance electron microscopy, and UV–visible transmission spectrum. The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO_2 thin films with thicknesses of 30 nm and 60 nm. The final results revealed that the best thickness of TiO_2 thin films for our fabricated cells was 30 nm. The cell with vanadium-doped TiO_2 thin film showed slightly higher power conversion efficiency and great J_(sc) of 10.7 mA/cm~2 compared with its pure counterpart. In the cells using 60 nm pure and vanadium-doped TiO_2 layers, the cell using the doped layer showed much higher efficiency. It is remarkable that the external quantum efficiency of vanadium-doped TiO_2 thin film was better in all wavelengths.     

Morphological and electrical properties of SrTiO_3/TiO_2/SrTiO_3 sandwich structures prepared by plasma sputtering

SrTiO_3(STO) and TiO_2 are insulating materials with large dielectric constants and opposite signs of the quadratic coefficient of voltage(α). Insertion of a TiO_2 thin film between STO layers increases the linearity of the capacitance in response to an applied voltage, to meet the increasing demand of large-capacitance-density dynamic random access memory capacitors. Both STO and TiO_2 suffer from the problem of high leakage current owing to their almost equivalent and low bandgap energies. To overcome this, the thickness of the thin TiO_2 film sandwiched between the STO films was varied. A magnetron sputtering system equipped with radio frequency and direct current power supply was employed for depositing the thin films. Ti N was deposited as the top and bottom metal electrodes to form a metal–insulator metal(MIM) structure,which exhibited a very large linear capacitance density of 21 fF/um~2 that decreased by increasing the thickness of the TiO_2 film. The leakage current decreased with an increase in the thickness of TiO_2, and for a 27-nm-thick film, the measured leakage current was 2.0 × 10~(-10) A. X-ray diffraction and Raman spectroscopy revealed that Ti N, STO, and TiO_2 films are crystalline and TiO_2 has a dominant anatese phase structure.     

Rare-earth-mediated magnetism and magneto-optical Kerr effects in nanocrystalline CoFeMn0.9RE0.1O4 thin films

A series of rare-earth (RE)-doped nanocrystalline CoFeMn_0.9RE_0.1O₄ thin films were prepared on monocrystalline silicon substrate by a sol–gel process, and the influences of the various RE³⁺ ions on the microstructure, magnetism and polar magneto-optical Kerr effects of the as-deposited films were examined. The results revealed that both of the magnetism and Kerr effect of CoFeMn_0.9RE_0.1O₄ films could be mediated by doping with various RE³⁺ ions. The trend of both M_S and H_C of CoFeMn_0.9RE_0.1O₄ films is similar to that of Bohr magneton across the series of rare-earth ions. The position of Kerr rotation peaks was red-shifted and their intensities increased, especially when doping with La³⁺, Tb³⁺, Y³⁺ or Yb³⁺ and so on. The enhanced MOKEs in CoFeMn_0.9RE_0.1O₄ nanocrystalline thin films might promise their applications for magneto-optical recording in the future.     

基于FTO/VO2/FTO结构的VO2薄膜电压诱导相变光调制特性

采用直流磁控溅射和后退火工艺在掺氟的SnO₂(FTO)导电玻璃衬底上制备VO₂薄膜, 研究了不同退火时间和不同比例的氮氧气氛对VO₂薄膜性能的影响, 对VO₂薄膜的结晶取向、表面形貌、表面元素的相对含量和透过率随波长变化进行了测试分析, 结果表明在最佳工艺条件下制备得到了组分相对单一的VO₂薄膜. 基于FTO/VO₂/FTO结构在VO₂薄膜两侧的透明导电膜上施加电压并达到阈值电压时, 观察到了明显的电流突变. 当接触面积为3 mm×3 mm时, 阈值电压为1.7 V, 阈值电压随接触面积的增大而增大. 与不加电压的情况相比, FTO/VO₂/FTO结构在电压作用下高低温的红外透过率差值可达28%, 经反复施加电压, 该结构仍保持性能稳定, 具有较强的电致调控能力.     

花状掺杂W-VO$lt;sub$gt;2$lt;/sub$gt;/ZnO热致变色纳米复合薄膜研究

为解决掺杂引起的二氧化钒薄膜的红外调制幅度下降以及二氧化钒复合薄膜相变温度需要进一步降低等问题, 采用纳米结构、掺杂改性和复合结构等多种机理协同作用的方案, 利用共溅射氧化法, 先在石英玻璃上制备高(002)取向的ZnO薄膜, 再在ZnO层上室温共溅射沉积钒钨金属薄膜, 最后经热氧化处理获得双层钨掺杂W-VO₂/ZnO纳米复合薄膜. 利用X射线衍射、X射线光电子能谱、扫描电镜和变温光谱分析等对薄膜的结构、组分、形貌和光学特性进行了分析. 结果显示, W-VO₂/ZnO 纳米复合薄膜呈花状结构, 取向性提高, 在保持掺杂薄膜相变温度(约39 ℃)和热滞回线宽度(约6 ℃)较低的情况下, 其相变前后的红外透过率差量增加近2倍, 热致变色性能得到协同增强. 关键词： 2')" href="#">VO₂ ZnO W掺杂 热致变色     

不同Sb含量p-SnO2薄膜的制备和特性

采用化学气相沉积方法, 利用Sb₂O₃/SnO作为源材料, 在蓝宝石衬底上制备出不同Sb掺杂量的SnO₂薄膜, 并在此基础上制作出p-SnO₂:Sb/n-SnO₂同质p-n 结器件. 研究表明, 随着Sb含量的增加, 样品表面变得平滑, 晶粒尺寸逐渐增大, 且晶体质量有所改善, 发现少量Sb的掺入可以起到表面活化剂的作用. Hall测量结果证实适量Sb的掺杂可以使SnO₂呈现p型导电特性, 当Sb₂O₃/SnO的质量比为1:5时, 其电学参数为最佳值. 此外, p-SnO₂:Sb/n-SnO₂同质p-n结器件展现出良好的整流特性, 其正向开启电压为3.4 V.     

X-ray photoelectron spectroscopy characterization of composite TiO2–poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide–poly(vinylidenefluoride) (TiO₂–PVDF) films developed for applications in the photocatalytic degradation of pollutants.

The composites were deposited on glass substrates by casting or spin coating from TiO₂–PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO₂–PVDF surface composition were used to optimize preparation conditions (composition of the TiO₂/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability.

The use of spin-coating deposition and the increase of TiO₂ amount in the DMF suspensions were found to improve the titanium surface content, although high TiO₂/PVDF ratios led to film instability. PVDF–TiO₂ films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO₂ and the role played by the PVDF film during the degradation process.