Crystallographic, dielectric and optical properties of SrBi2Ta2O9 thin films prepared by the polymeric precursor method

Strontium bismuth tantalate thin films were prepared on several substrates (platinized silicon (PvTi/SiO2/Si), n-type (100)-oriented and p-type (111)-oriented silicon wafers, and fused silica) by the solution deposition method. The resin was obtained by the polymeric precursor method, based on the Pechini process, using strontium carbonate, bismuth oxide, and tantalum ethoxide as starting reagents. Characterizations by XRD and SEM were performed for structural and microstructural evaluations. The electrical measurements, carried on the MFM configuration, showed P-r values of 6.24 muC/cm(2) and 31.5 kV/cm for the film annealed at 800 degreesC. The film deposited onto fused silica and treated at 700 degreesC presented around 80 % of transmittance.

Developments in hot-filament metal oxide deposition (HFMOD)

Hot-filament metal oxide deposition (HFMOD) is a variant of conventional hot-filament chemical vapor deposition (HFCVD) recently developed in our laboratory and successfully used to obtain high-quality, uniform films of MOx WOx and VOx. The method employs the controlled oxidation of a filament of a transition metal heated to 1000 degrees C or more in a rarefied oxygen atmosphere (typically, of about 1 Pa). Metal oxide vapor formed on the surface of the filament is transported a few centimetres to deposit on a suitable substrate. Key system parameters include the choice of filament material and diameter, the applied current and the partial pressures of oxygen in the chamber. Relatively high film deposition rates, such as 31 nm min(-1) for MoOx, are obtained. The film stoichiometry depends on the exact deposition conditions. MoOx films, for example, present a mixture of MoO2 and MoO3 phases, as revealed by XPS. As determined by Li+ intercalation using an electrochemical cell, these films also show a colouration efficiency of 19.5 cm(2) C-1 at a wavelength of 700 nm. MOx and WOx films are promising in applications involving electrochromism and characteristics of their colouring/bleaching cycles are presented. The chemical composition and structure of VOx films examined using IRRAS (infrared reflection-absorption spectroscopy), RBS (Rutherford backscattering spectrometry) and XPS (X-ray photoelectron spectrometry) are also presented. (c) 2007 Elsevier B.V. All rights reserved.

Superparamagnetic Ni:SiO2-C nanocomposites films synthesized by a polymeric precursor method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of in concentration in the starting solution on the structural and electrical properties of ZnO films prepared by the pyrosol process at 450°C

Undoped and indium-doped Zinc oxide (ZnO) solid films were deposited by the pyrosol process at 450°C on glass substrates from solutions where In/Zn ratio was 2, 5, and 10 at.%. Electrical measurements performed at room temperature show that the addition of indium changes the resistance of the films. The resistivities of doped films are less than non-doped ZnO films by one to two orders of magnitude depending on the dopant concentration in the solution. Preferential orientation of the films with the c-axis perpendicular to the substrate was detected by X-ray diffraction and polarized extended X-ray absorption fine structures measurements at the Zn K edge. This orientation depends on the indium concentration in the starting solution. The most textured films were obtained for solutions where In/Zn ratio was 2 and 5 at.%. When In/Zn = 10 at.%, the films had a nearly random orientation of crystallites. Evidence of the incorporation of indium in the ZnO lattice was obtained from extended X-ray absorption fine structures at the In and Zn K edges. The structural analysis of the least resistive film (Zn/In = 5 at.%) shows that In substitutes Zn in the wurtzite structure. © 2000 Elsevier Science B.V. All rights reserved.

Crystallographic, dielectric and optical properties of SrBi 2Ta2O9 thin films prepared by the polymeric precursor method

Strontium bismuth tantalate thin films were prepared on several substrates (platinized silicon (Pt/Ti/SiO 2 /Si), n -type (100)-oriented and p -type (111)-oriented silicon wafers, and fused silica) by the solution deposition method. The resin was obtained by the polymeric precursor method, based on the Pechini process, using strontium carbonate, bismuth oxide, and tantalum ethoxide as starting reagents. Characterizations by XRD and SEM were performed for structural and microstructural evaluations. The electrical measurements, carried on the MFM configuration, showed P r values of 6.24 μC/cm 2 and 31.5 kV/cm for the film annealed at 800 C. The film deposited onto fused silica and treated at 700 C presented around 80% of transmittance. © 2002 Taylor & Francis.

Corrosion protection of fluorzirconate glasses coated by a layer of surface modified tin oxide nanoparticles

The protection efficiency against water corrosion of fluorozirconate glass, ZBLAN, dip-coated by nanocrystalline tin oxide film containing the organic molecule Tiron® was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical bonding structure of the surface region and morphology were studied before and after two water exposure periods of 5 and 30 min. The results of the analysis for the as-grown sample revealed a SnO1.6 phase containing carbon and sulfur, related to Tiron®, and traces of elements related to ZBLAN (Zr, F, Ba). This fact and the clear evidence of the presence of tin oxifluoride specie (SnOxF y) indicates a diffusion of the glass components into the porous coating. After water exposure, the increase of the oxygen concentration accompanied by a strong increase of Zr, F, Ba and Na content is interpreted as filling of the nanopores of the film by glass compounds. The formation of a compact protective layer is supported by the morphological changes observed by AFM. © 2005 Elsevier B.V. All rights reserved.

Preparation of films from aluminum acetylacetonate by plasma sputtering

Aluminum acetylacetonate has been reported as a precursor for the deposition of alumina films using different approaches. In this work, alumina-containing films were prepared by plasma sputtering this compound, spread directly on the powered lowermost electrode of a reactor, while grounding the substrates mounted on the topmost electrode. Radiofrequency power (13.56 MHz) was used to excite the plasma from argon atmosphere at a working pressure of 11 Pa. The effect of the plasma excitation power on the properties of the resulting films was studied. Film thickness and hardness were measured by profilometry and nanoindentation, respectively. The molecular structure and chemical composition of the layers were analyzed by Fourier transform infrared spectroscopy and energy dispersive spectroscopy. Surface micrographs, obtained by scanning electron microscopy, allowed the determination of the sample morphology. Grazing incidence X-ray diffraction was employed to determine the structure of the films. Amorphous organic layers were deposited with thicknesses of up to 7 μm and hardness of around 1.0 GPa. The films were composed by aluminum, carbon, oxygen and hydrogen, their proportions being strongly dependent on the power used to excite the plasma. A uniform surface was obtained for low-power depositions, but particulates and cracks appeared in the high-power prepared materials. The presence of different proportions of aluminum oxide in the coatings is ascribed to the different activations promoted in the metalorganic molecule once in the plasma phase. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Structural transition of ZnO thin films produced by RF magnetron sputtering at low temperatures

Zinc oxide (ZnO) thin films were prepared using reactive radio-frequency magnetron sputtering of a pure metallic zinc target onto glass substrates. The evolution of the surface morphology and the optical properties of the films were studied as a function of the substrate temperature, which was varied from 50 to 250 C. The surface topography of the samples was examined using atomic force microscopy (AFM), and their optical properties were studied via transmittance measurements in the UV-Vis-NIR region. DRX and AFM analyses showed that the surface morphology undergoes a structural transition at substrate temperatures of around 150 C. Actually, at 50 C the formation of small grains was observed while at 250 C the grains observed were larger and had more irregular shapes. The optical gap remained constant at ∼3.3 eV for all films. In the visible region, the average optical transmittance was 80 %. From these results, one can conclude that the morphological properties of the ZnO thin films were more greatly affected by the substrate temperature, due to mis-orientation of polycrystalline grains, than were the optical properties. © 2013 Springer Science+Business Media New York.

Amperometric glucose biosensor based on layer-by-layer films of microperoxidase-11 and liposome-encapsulated glucose oxidase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of Fe-doping on the structural, microstructural, optical, and ferroeletric properties of Pb1/2Sr1/2Ti1-xFexO3 oxide prepared by spin coating technique

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and optical properties of Cu2O crystalline electrodeposited films

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparation of TiO2/SnO2 Thin Films by Sol-Gel Method and Periodic B3LYP Simulations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synergy between polyaniline and OMt clay mineral in Langmuir-Blodgett films for the simultaneous detection of traces of metal ions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Heterojunction between Al2O3 and SnO2 thin films for application in transparent FET

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Innovative low temperature plasma approach for deposition of alumina films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)