Al2O3/TiO2复合膜的结构及光催化性能

利用电沉积方法在铝硫酸阳极氧化膜表面制备了具有光催化活性的T iO2薄膜。分析了A l2O3/T iO2复合膜的结构,观察了薄膜表面形貌及断面构造,并分析了薄膜表面的化学成分,通过紫外光照射下甲基橙溶液的光催化降解反应初步研究了该复合膜的光催化活性。结果表明,未经热处理的A l2O3/T iO2复合膜处于非晶态,550℃热处理3 h后,T iO2转变为锐钛矿结构;沉积在铝氧化膜表面的T iO2薄膜厚度约5μm,呈均匀不连续状态,表面存在大量裂纹,电沉积T iO2过程中基体氧化铝存在着部分溶解;薄膜表面主要由T i、O两种元素构成,同时存在较少量的A l、S、K等元素。该A l2O3/T iO2复合膜可光催化降解甲基橙溶液,具有光催化活性。     

冷冻处理凹凸棒黏土对PVA/APT纳米复合膜性能的影响

以聚乙烯醇(PVA)和经过不同时间冷冻处理的凹凸棒黏土(APT)为原料,采用溶液-流延成膜法,制备了PVA/APT纳米复合膜,通过红外光谱、XRD和SEM对纳米复合膜的结构和形貌进行了表征,并对复合膜的力学性能及耐水性能进行了测试.结果表明,与未冷冻处理APT相比,经冷冻处理后APT的棒晶可以更好的分散在PVA基体中,纳米复合膜的力学性能和耐水性有明显提高.其中,以冷冻处理16 h APT制备的纳米复合膜性能最优,其拉伸强度、断裂延伸率和耐水性分别提高了17.4％、25.4％和19.2％.     

Dielectric and Ion Transport Studies in [PVA: LiC2H3O2]: Li2Fe5O8 Polymer Nanocomposite Electrolyte System

The present work deals with the findings on optical and ion transport behavior in a ferrite-doped polymer nanocomposite electrolyte system, namely, [(100 ? x) PVA + xLiC₂H₃O₂]: yLiFe₅O₈. This polymer electrolyte system has been characterized by SEM, DSC, IR and C-V measurements. The addition of filler seems to disturb the crystalline nature of the host matrix while the doping of salt shows a similar structure, but with a separate entity in SEM images. DSC studies reflect the interaction of the salt/filler with polymer with a change in morphology of the composite system. These results are well-corroborated by IR data. The effect of salt or filler in the enhancement of the a.c. conductivity of nanocomposite polymer electrolyte (NCPE) as well as dielectric relaxation behavior has been investigated with the help of impedance spectroscopy data. The a.c. conductivity of nanocomposite polymer electrolytes is seen to be best described by the universal power law.     

戊二醛交联碱木质素/聚乙烯醇膜的制备及其光学性能

以碱木质素和聚乙烯醇(PVA)为原料,以戊二醛为交联剂利用流延法制备了碱木质素/PVA交联反应膜。通过单因素实验考查了碱木质素加入量、戊二醛加入量对木质素／PVA反应膜光学性能的影响。采用SEM和FT-IR方法分析反应膜的表面形貌和化学结构,紫外可见光谱法分析了交联膜的光学性能。结果表明:当碱木质素和聚乙烯醇质量比为1∶10,戊二醛加入量 1.67 %,薄膜的透光率和吸光度都较好。碱木质素/PVA薄膜结构中有醚键生成,碱木质素和PVA发生了交联反应;碱木质素/PVA反应薄膜表面较光滑;加入碱木质素后,薄膜在紫外光区的吸光度提高了近 90 %,在可见光区的透过率降低了近 40 %,碱木质素对薄膜的吸光度和透过率影响较大;戊二醛的加入量增多可见光区透过率有所增大,但戊二醛对薄膜在紫外区吸光度变化不大,薄膜的紫外线吸收主要是受碱木质素的影响。碱木质素/PVA反应膜可作为良好的紫外吸收材料。     

Structure and thermal properties of Al2O3-doped Gd3TaO7 as potential thermal barrier coating

In this paper, a series of solid solutions ceramics of (Al_xGd_1-x)₃TaO₇ (x = 0, 0.01, 0.03, 0.05) were synthesized via solid-state reaction. X-ray diffraction (XRD) and Raman spectroscopy analysis indicated that the crystal structure of (Al_xGd_1-x)₃TaO₇ ceramics is weberite in spite of the content of Al³⁺ is up to 5 mol.%. The thermal conductivities of (Al_xGd_1-x)₃TaO₇ ceramics range from 1.37 W?m^?1 K^?1 to 1.47 W?m^?1 K^?1 at 900 ℃, which is much lower than that of 7–8 YSZ (about 2.5 W?m^?1 K^?1). The thermal expansion coefficients (TECs) of (Al_xGd_1-x)₃TaO₇ ceramics vary in the range of 6–10 × 10^-6 K^-1 within the temperature range 100–1200 ℃, and the values are close to the TECs of 7–8 YSZ. Given the low thermal conductivity and high thermal expansion coefficients of (Al_xGd_1-x)₃TaO₇ ceramics, they have the potential to be the next generational thermal barrier coating materials.     

AP/SiO2/Fe2O3纳米复合材料的制备与表征

采用溶胶凝胶法制备了AP/SiO2/Fe2O3纳米复合材料.用扫描电镜、X射线衍射仪(XRD)对产物的结构进行了表征.用差示扫描量热仪(DSC)对原料和产物的热分解性能进行了表征.结果表明,AP/SiO2/Fe2O3纳米复合材料是以SiO2/Fe2O3为骨架,AP进入凝胶孔洞中形成的.Fe2O3均匀分布在纳米凝胶骨架中.经热处理后αFe2O3的晶粒度为9.7nm,有效防止了纳米Fe2O3的团聚;AP均匀地分散在凝胶孔洞中,晶粒度为80～250 nm.AP/SiO2 /Fe2O3纳米复合材料能有效促进AP的热分解,使其高温分解峰温降低84.77℃,分解热提高987.1J/g.     

退火温度对纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜结构和磁性的影响

采用溶胶-凝胶旋涂法制备纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜.用X射线衍射仪、原子力显微镜及振动样品磁强计分析复合薄膜的结构、表面形貌和磁性,研究退火温度对复合薄膜结构和磁性的影响.结果表明:经800℃退火处理的样品中已形成Co0.8Mg0.2Fe2O4晶相;随着退火温度的提高,Co0.8Mg0.2Fe...     

Preparation and Characterization of PAn-HPC/Fe3O4 and PAn-HPC/Fe2O3 Nanocomposite Using Hydroxypropylcellulose as a Steric Stabilizer

Nanocomposite of polyaniline containing Fe₃O₄ and Fe₂O₃ was synthesized by a chemical method using hydroxypropylcellulose as a steric stabilizer. The characteristics of product such as, morphology, conductivity, and particle size were studied. The results indicate that, these properties were dependent on the surfactant, amount and type of metallic oxide. When the concentration of Fe₂O₃ and Fe₃O₄ increased from 1 to 5 g/L, in PAn/Fe₂O₃ and PAn/Fe₃O₄ composites the conductivity decreased from 1.2 × 10^?6 to 1.1 × 10^?8 and 2.8 × 10^?6 to 1.1 × 10^?8S/cm, respectively, while the particle size of nanocomposite increased from 96 to 110, and 97 to 115 nm, respectively.     

Solvothermal synthesis of columnar Gd2O2S:Eu3+ and a comparative study with columnar Gd2O3:Eu3+

Columnar Gd₂O₂S:Eu³⁺ nanophosphors have been synthesized through solvothermal reaction and subsequent calcination process. The structure, morphology, and luminescence properties of samples were investigated via X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectra, UV-vis absorption spectra, field emission scanning electron microscope (FE-SEM), and photoluminescence (PL) spectra. The Judd-Ofelt (J-O) parameters of Gd₂O₂S:Eu³⁺ nanophosphors with different doping concentration were calculated by emission spectra to understand the symmetry, coordination environment, and luminescence behavior of Eu³⁺ ions in Gd₂O₂S matrix. In addition, the luminescence properties of columnar Gd₂O₂S:Eu³⁺ and Gd₂O₃:Eu³⁺ were compared in detail. The comparison results show that there are subtle differences in luminescence intensity, main peak position, luminescence color, and fluorescence lifetime between them, which are closely related to their different substrate's structure, including the band-gap energy, crystallinity, and symmetry, etc.     

Massive Transformation in Gd2O3-Bi2O3 Ceramics

Gd₂O₃-doped Bi₂O₃ polycrystalline ceramic samples containing between 10 and 26 mol% Gd₂O₃ were fabricated by pressureless sintering of powder compacts. As-sintered samples were cubic (CaF₂ structure). The cubic solid solutions underwent transformation to a rhombohedral phase when annealed at lower temperatures. Under certain conditions, the cubic phase fully transformed to the rhombohedral phase of the same composition, and the kinetics were thermally activated. This suggested that the cubic → rhombohedral transformation was a massive transformation. The transition temperatures for the occurrence of a massive transformation were experimentally determined by measuring the conductivity as a function of temperature, as well as by measuring growth rate of the rhombohedral precipitates as a function of temperature. The activation enthalpy for interface motion was measured to be ∼200 kJ/mol for the samples studied. The kinetics of cubic → rhombohedral transformation could be described by the Johnson-Mehl-Avrami equation.     

Structural and Optical Properties of Sol–Gel-Derived Au/BaTiO3 Nanocomposite Thin Films

Au/BaTiO₃ nanocomposite thin films with different Au concentrations were prepared by a sol–gel process. The films were characterized using X-ray diffraction, thermal analyses, X-ray absorption spectroscopy, UV-vis spectroscopy, and transmission electron microscopy. The effects of Au concentration and annealing temperature on the structural and optical properties of composite films were investigated. Gold doping lowered the crystallization temperature of as-synthesized amorphous BaTiO₃ and enhanced its crystallinity in post-deposition annealing. The Au–BaTiO₃ interface was also investigated and no alloying occurred between Au and BaTiO₃. The evolution of Au surface plasmon resonance spectra with increasing annealing temperature was observed in the 10 mol% Au/BaTiO₃ thin films. The variations of band-gap energy for Au/BaTiO₃ films were also discussed.     

Structural,Electrical and Optical Properties of PVC/ZnTe Nanocomposite Thin Films

Journal of Inorganic and Organometallic Polymers and Materials - ZnTe nanoparticles (NPs) were synthesized using hydrothermal method and then were dispersed in poly(vinyl-chloride) (PVC) to prepare...     

PVA醇解度对热致变导电PVA/AgNO3_薄膜结构和性能的影响

采用不同醇解度的聚乙烯醇(PVA)和硝酸银(AgNO_3)为原料,通过溶液成膜法制备了在固相具有热致变性能的导电PVA/AgNO_3复合薄膜。采用FTIR表征了各种醇解度的PVA与Ag+之间的络合作用。通过TG、SEM、X-射线衍射、X射线能谱(EDS)等方法研究了不同醇解度的PVA/AgNO_3复合薄膜的热性能和热处理后薄膜表面形貌和结构,结果表明:不同醇解度的PVA/AgNO_3复合薄膜在160~200℃均有一明显失重峰;随着醇解度增加,SEM显示热处理后纳米银粒子尺寸减小;实验发现在温度为170~200℃时,醇解度为80%、88%、92%的PVA/AgNO_3复合薄膜其表面电阻率能从300~500 kΩ突然降低到5~20Ω(降低4~5个数量级),而醇解度为97%的PVA/AgNO_3复合薄膜表面电阻率不能发生突变,反而升高。这种具有独特电阻率-温度特性的薄膜在热敏电阻或温度传感器等方面有潜在应用。     

热处理温度对Co_(0.8)Fe_(2.2)O_4/SiO_2纳米复合薄膜结构和磁性能的影响

采用溶胶-凝胶旋涂法在经表面氧化的Si(100)基片上制备了Co0.8Fe2.2O4/Si O2纳米复合薄膜。利用X射线衍射仪、扫描电子显微镜和振动样品磁强计对Co0.8Fe2.2O4/Si O2纳米复合薄膜的结构、形貌和磁性能进行分析,研究了热处理温度对复合薄膜结构和磁性能的影响。结果表明:热处理温度高于750℃时复合薄膜中Co0.8Fe2.2O4呈现尖晶石结构;当热处理温度从750℃升高到1 100℃,复合薄膜中Co0.8Fe2.2O4的晶粒尺寸从6 nm增大到34 nm,晶胞常数从0.836 9 nm增大到0.839 5 nm。样品的矫顽力随热处理温度的升高先增大后减小,经1 000℃热处理样品的矫顽力达到298.3 k A/m。     

PVA/Nano-SiO_2杂化膜的制备及性能研究

以聚乙烯醇(PVA)和正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶(Sol-Gel)技术,制备出不同nano-SiO2含量的PVA/nano-SiO2杂化膜,并采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)等仪器测试和分析了杂化膜的结构和性能。结果表明:随着nano-SiO2含量的增加,PVA杂化膜的耐水性能增强,结晶能力下降,而力学性能呈现先增大后减小的趋势。当nano-SiO2的加入量在10%左右时,断裂伸长率由纯PVA膜的34.74%提高到55.52%,拉伸强度从33.08 MPa增加到49.98 MPa;而当nano-SiO2含量增加到20%以上时,nanoSiO2粒子会发生团聚,使得杂化膜的力学性能变差。     

PVA/Fe2O3磁敏感性水凝胶的制备及性能

采用循环冷冻-解冻方法制备了聚乙烯醇(PVA)/Fe2O3磁敏感性水凝胶. 考察了水凝胶的力学性能、溶胀性能和磁敏感性,并用扫描电镜观察了其表面形貌. 结果表明,当Fe2O3含量为1%(w)时,水凝胶的力学性能最好;水凝胶的溶胀度和脱水率随时间增加有相似的变化趋势,都随磁性粒子含量升高而降低;溶胀性能降低其交联程度增加;PVA和Fe2O3相容性较好;水凝胶在3000 Oe的磁场强度下达到饱和,呈现出很强的顺磁性,磁滞损耗较多,表明具有较好的磁敏感性.     

Flexible Polymer/Clay Nanocomposite Films as Oxygen Supply Materials

PIB/MMT nanocomposite films containing UHP are fabricated and characterized for potential applications in wounded‐skin oxygen delivery and/or tooth cleaning. The UHP acts as a source of oxygen, whereas MMT creates a pathway for water molecules penetrating the film in order to generate a controlled release of H₂O₂ molecules. Most UHP particles are uniformly dispersed throughout the entire thickness of the films. DMA measurements indicate that the material retains most of its structural characteristics when exposed to water. SEM measurements show that no interface exists between individually spread multilayers. SAXS measurements indicate that the clay platelets are predominantly exfoliated and randomly oriented within the film. Controlled release of H₂O₂ is found over a period of ≈90–100 min.

     

Photoluminescent Epoxy/Gd2O3:Eu3+ UV‐cured Nanocomposites

UV‐cured photoluminescent coatings emitting in the visible spectral region are obtained by dispersing Gd₂O₃:4 mol% Eu³⁺ nanorods in three different commercially available photocurable epoxy resins. The effect of the concentration of the Gd₂O₃:4 mol% Eu³⁺ nanorods on the kinetics of the photocuring reaction is followed using real‐time FT‐IR. Thermal and the mechanical properties of the cured films are also investigated. Moreover, the effect of the matrix and nanorod concentration in the composites on the emission and excitation spectra and the ⁵D₀(C₂) decay time of Eu³⁺ is evaluated. The composite materials present original photoluminescence properties and demonstrate the potential of UV curing as a technique to develop smart photoactive coatings.