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以氯化醇钛盐表面反应法制备系列TiO2/SiO2,根据XRD,Raman和DRS表征分析,载体表面具有分子级分散的锐钛矿型TiO2微晶粒子和非晶TiOx物种.与本体TiO2相比,TiO2/SiO2的吸收带边显著蓝移,能隙增大为3.96 eV.当金属M(M:Pd,Cu和Ni)负载于TiO2/SiO2表面,可使其光吸收域扩展到可见光区,并引起吸收带边红移.相对Pd的负载,Cu,Ni的负载对TiO2/SiO2的LMCT带影响更大,其中Cu-TiO2/SiO2的能隙减小为3.68 eV.当金属氧化物MoO3负载于TiO2/SiO2上时,可以调变TiO2/SiO2的吸收带边并增强对可见光的吸收;随MoO3载量的增加,表面物种的相互作用增强,形成Mo-O-Ti复合结构,增强了LMCT带的吸收强度,并使能隙减小为3.81 eV. 相似文献
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利用磁控溅射在重掺硼硅(p+-Si)衬底上分别沉积TiO2薄膜和掺硼的TiO2(Ti O2∶B)薄膜,并经过氧气氛下600℃热处理,由此形成相应的TiO2/p+-Si和TiO2∶B/p+-Si异质结。与Ti O2/p+-Si异质结器件相比,TiO2∶B/p+-Si异质结器件的电致发光有明显的增强。分析认为:TiO2∶B薄膜经过热处理后,B原子进入TiO2晶格的间隙位,引入了额外的氧空位,而氧空位是TiO2/p+-Si异质结器件电致发光的发光中心,所以上述由B掺杂引起的氧空位浓度的增加是TiO2∶B/p+-Si异质结器件电致发光增强的原因。 相似文献
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TiO_2对α-Fe_2O_3纳米微粒拉曼散射效应的影响 总被引:2,自引:2,他引:0
选取α Fe2O3和TiO2研究一种氧化物对另一种氧化物的拉曼散射效应。采用Sol gel方法制备纳米α Fe2O3/TiO2复合微粒,α Fe2O3粒径及含量分别为20nm、150nm和3%、6%、12%。制备过程中调节水解时的pH值和热处理温度,得到掺杂α Fe2O3粒子的不同晶型的TiO2纳米颗粒。Raman测量结果显示,α Fe2O3粒径越小、含量越高,TiO2对其散射效应的影响越大。不同的TiO2晶型对α Fe2O3纳米粒子的拉曼增强效应也不同。锐钛矿型及金红石型TiO2对α Fe2O3有一定的拉曼增强作用,当水解pH值较小时,得到板钛矿型TiO2,由于部分板钛矿型TiO2振动声子模的峰位与α Fe2O3的重叠,所以尚难观察它对α Fe2O3的拉曼增强效应。 相似文献
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We present the linear and nonlinear optical studies on TiO2-SiO2 nanocomposites with varying compositions. Opti- cal band gap of the material is found to vary with the amount of SiO2 in the composite. The phenomenon of two-photon absorption (TPA) in TiO2/SiO2 nanocomposites has been studied using open aperture Z-scan technique. The nanocom- posites show better nonlinear optical properties than pure TiO2, which can be attributed to the surface states and weak dielectric confinement of TiO2 nanoparticles by SiO2 matrix. The nanocomposites are thermally treated and similar studies are performed. The anatase form of TiO2 in the nanocomposites shows superior properties relative to the amorphous and rutile counterpart. The involved mechanism is explained by rendering the dominant role played by the excitons in the TiO2 nanoparticles. 相似文献
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TiO2/SnO2复合氧化物的制备和光谱特性 总被引:6,自引:0,他引:6
为了研究TiO2/SnO2复合氧化物的光学特性,用胶体化学方法制备了以SnO2为内核的TiO2/SnO2复合氧化物,并且用紫外-可见光吸收光谱、X射线衍射和红外光谱对TiO2/SnO2复合氧化物的特性进行了分析.结果显示TiO2和TiO2/SnO2的能带宽度分别为4.13和3.86 eV,表现出量子尺寸效应;TiO2/SnO2在紫外区域具有宽的强吸收带.X射线衍射中TiO2的(110)衍射峰的位置移动了1.6°,强度也发生了变化;与TiO2红外光谱相比,TiO2/SnO2中Ti-O键的伸缩振动由500cm-1移到了656 cm-1,并有560 cm-1的肩峰,与吸附水相应的1650 cm-1附近的吸收峰和3420 cm-1的吸收峰均有所增加. 相似文献
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本文采用基于周期性密度泛函理论研究了Cu/N表面沉积共掺杂对锐钛矿相TiO2(001)面的修饰作用.计算了Cu在不同位置掺杂TiO2(101)面和(001)面的形成能,并在此基础上计算N不同位置掺杂TiO2(001)面及Cu/TiO2(001)面的形成能,通过形成能的比较获得了表面共掺杂的最优化结构.在此基础上计算了最稳定结构的能带结构及态密度,并与S单掺杂TiO2(001)面最稳定结构进行了对比.通过对结果的分析发现:Cu/N在(001)表面的沉积共掺杂有效降低了TiO2的禁带宽度,并在表面形成CuO2相,更利于提高其光催化活性. 相似文献
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溶胶-凝胶法制备TiO2-SiO2多层增透膜 总被引:3,自引:3,他引:0
在酸催化体系中以钛酸丁酯为前驱体制得TiO2溶胶,以正硅酸乙酯(TEOS)为前驱体制得SiO2溶胶,采用提拉法在普通载玻片上镀膜。辅助MASS膜系设计软件进行模拟计算,得到了透射率为99%的膜片。根据理论模拟结果,实验采用交叉镀膜,制备出了宽带增透TiO2-SiO2多层膜,其方法有别于以往的TiO2/SiO2复合膜法。用紫外-可见分光光度计测量了样品的透射光谱。实验发现,样品具有明显的宽带增透效果:在400-700nm波段,当光线垂直入射时,增透6%左右;45°角入射时,可增透10%。 相似文献
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Momtchil Dimitrov Ljubomira Ivanova Tanya Tsoncheva Ivan Mitov 《Applied Surface Science》2009,255(7):4322-4328
The state of the iron oxide nanoparticles, supported on ultradispersed diamond (UDD) powders is studied by X-ray diffraction, nitrogen physisorption, temperature-programmed reduction, FTIR and Mössbauer spectroscopy. Methanol decomposition to hydrogen and CO is used as a catalytic test. The peculiarities of the iron oxide species strongly depend on the detonation procedure used for the UDD powders preparation as well as on the iron modification procedure. 相似文献
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Attila Lengyel Gyula Tolnai Zoltán Klencsár Vijayendra Kumar Garg Aderbal Carlos de Oliveira L. Herojit Singh Zoltán Homonnay Roland Szalay Péter Németh Bálint Szabolcs Mira Ristic Svetozar Music Ernő Kuzmann 《Journal of nanoparticle research》2018,20(5):137
57Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites. 相似文献
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Ilker Dincer Onur Tozkoparan Sergey V. German Alexey V. Markin Oguz Yildirim Gennady B. Khomutov Dmitry A. Gorin Sergey B. Venig Yalcin Elerman 《Journal of magnetism and magnetic materials》2012
Aqueous colloidal suspension of iron oxide nanoparticles has been synthesized. Z-potential of iron oxide nanoparticles stabilized by citric acid was −35±3 mV. Iron oxide nanoparticles have been characterized by the light scattering method and transmission electron microscopy. The polyelectrolyte/iron oxide nanoparticle thin films with different numbers of iron oxide nanoparticle layers have been prepared on the surface of silicon substrates via the layer-by-layer assembly technique. The physical properties and chemical composition of nanocomposite thin films have been studied by atomic force microscopy, magnetic force microscopy, magnetization measurements, Raman spectroscopy. Using the analysis of experimental data it was established, that the magnetic properties of nanocomposite films depended on the number of iron oxide nanoparticle layers, the size of iron oxide nanoparticle aggregates, the distance between aggregates, and the chemical composition of iron oxide nanoparticles embedded into the nanocomposite films. The magnetic permeability of nanocomposite coatings has been calculated. The magnetic permeability values depend on the number of iron oxide nanoparticle layers in nanocomposite film. 相似文献
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土壤氧化铁的高光谱响应研究 总被引:3,自引:0,他引:3
通过分析野外采集的13个土种的不同氧化铁含量原始土样和人工配制不同氧化铁含量土样的高光谱特征,研究了氧化铁对土壤反射率、土壤线参数、土壤有机质高光谱特征、土壤反射率光谱曲线形态的影响。研究结果表明,随氧化铁含量的增加,350~570 nm波段反射率降低,570~2 500 nm波段的反射率增加,氧化铁去除量与反射率变化量之间的相关性不明显;氧化铁含量与土壤线斜率呈线性负相关,与截距呈线性正相关,且均达到极显著相关水平,表明利用土壤线参数反演氧化铁含量具有可行性;在622~851 nm波段,氧化铁对有机质的高光谱特征具有明显的抑制作用;通过去包络线和统计F值与光谱角值表明,氧化铁对土壤反射光谱曲线形态有影响。 相似文献
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The microplasma synthesis method of multicomponent oxide coatings including iron oxide on an aluminum alloy surface has been studied. The homogeneous electrolytes containing iron complexes with Edta4− under pH 9-10 have been used. The dynamics reducing the pH of the electrolyte during formation process have been studied. The content of iron in the coatings has been measured spectrophotometricaly. Morphlogy and phase composition of the coatings have been studied by the scanning electron microscopy and X-ray powder diffraction. 相似文献
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For fundamental studies of the atmospheric corrosion of steel, it is useful to identify the iron oxide phases present in rust
layers. The nine iron oxide phases, iron hydroxide (Fe(OH)2), iron trihydroxide (Fe(OH)3), goethite (α-FeOOH), akaganeite (β-FeOOH), lepidocrocite (γ-FeOOH), feroxyhite (δ-FeOOH), hematite (α-Fe2O3), maghemite (γ-Fe2O3) and magnetite (Fe3O4) are among those which have been reported to be present in the corrosion coatings on steel. Each iron oxide phase is uniquely
characterized by different hyperfine parameters from M?ssbauer analysis, at temperatures of 300K, 77K and 4K. Many of these
oxide phases can also be identified by use of Raman spectroscopy. The relative fraction of each iron oxide can be accurately
determined from the M?ssbauer subspectral area and recoil-free fraction of each phase. The different M?ssbauer geometries
also provide some depth dependent phase identification for corrosion layers present on the steel substrate. Micro-Raman spectroscopy
can be used to uniquely identify each iron oxide phase to a high spatial resolution of about 1 μm.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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A novel method for fabricating magnetic iron oxide nanoparticles was achieved by using transparent vermicelli template as a new stabilizing material. The morphology of the as-prepared magnetic iron oxide deposited on the surface of vermicelli was observed as nanoclusters. The magnetization of the magnetic iron oxide nanoparticles at room temperature was decreased after carbonization at 200 °C. Therefore the thermal decomposition of iron oxide nanoparticles stabilized by starch vermicelli template yielded iron oxide/carbon nanocomposites with the soft magnetic behavior which are useful for biomedical applications. 相似文献
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Zhanhu Guo Koo Shin Amar B. Karki David P. Young Richard B. Kaner H. Thomas Hahn 《Journal of nanoparticle research》2009,11(6):1441-1452
The effect of iron oxide nanoparticle addition on the physicochemical properties of the polypyrrole (PPy) was investigated.
In the presence of iron oxide nanoparticles, PPy was observed in the form of discrete nanoparticles, not the usual network
structure. PPy showed crystalline structure in the nanocomposites and pure PPy formed without iron oxide nanoparticles. PPy
exhibited amorphous structure and nanoparticles were completely etched away in the nanocomposites formed with mechanical stirring
over a 7-h reaction. The thermal stability of the PPy in the nanocomposites was enhanced under the thermo-gravimetric analysis
(TGA). The electrical conductivity of the nanocomposites increased greatly upon the initial addition (20 wt%) of iron oxide
nanoparticles. However, a higher nanoparticle loading (50 wt%) decreased the conductivity as a result of the dominance of
the insulating iron oxide nanoparticles. Standard four-probe measurements indicated a three-dimensional variable-range-hopping
conductivity mechanism. The magnetic properties of the fabricated nanocomposites were dependent on the particle loading. Ultrasonic
stirring was observed to have a favorable effect on the protection of iron oxide nanoparticles from dissolution in acid. A
tight polymer structure surrounds the magnetic nanoparticles, as compared to a complete loss of the magnetic iron oxide nanoparticles
during conventional mechanical stirring for the micron-sized iron oxide particles filled PPy composite fabrication. 相似文献
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X.Q. Zhao B.X. Liu Y. Liang Z.Q. Hu 《Applied Physics A: Materials Science & Processing》1997,64(5):483-486
5 . The γ-Fe particles, because of their paramagnetic nature, are very convenient for investigation on the attributes of iron
oxide layers formed on the particle surfaces. Structures, morphologies and magnetic properties of the oxide layers covering
the iron ultrafine particles have been studied using transmission electron microscopy observation, magnetic property measurement,
X-ray diffraction and annealing treatment. Convincing evidences established that the iron oxide layers are not continuous
and consist of very fine crystallites, and that these layers are non-ferromagnetic and have no contribution to the saturation
magnetization of the iron particles. The iron oxide layers formed at room temperature was determined to be Fe3O4. Additionally, a brief annealing of the iron particles in air were performed to examine magnetic properties of the formed
iron oxide layers and ultrafine oxide particles.
Received: 30 April 1996/Accepted: 5 November 1996 相似文献
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Satoshi Seino Takuya Kinoshita Takashi Nakagawa Takao Kojima Ryoichi Taniguci Shuichi Okuda Takao A. Yamamoto 《Journal of nanoparticle research》2008,10(6):1071-1076
Composite nanoparticles consisting of gold and iron oxide were synthesized in aqueous solution systems by using a high-energy
electron beam. The electron irradiation induces radiation-chemical reaction to form metallic gold nanoparticles. These gold
nanoparticles were firmly immobilized on the surface of the support iron oxide nanoparticles. Surface of the support iron
oxide nanoparticles are almost fully coated with fine gold nanoparticles. The size of these gold nanoparticles depended on
the concentrations of gold ions, polymers and iron oxide nanoparticles in the solutions before the irradiation. 相似文献