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1.
This paper presents a new sol-gel process to prepare molybdenum oxide thin films. A molybdenum acetylacetonate sol was prepared by employing the system CH3COCH2COCH3/MoO3/C6H5CH3/HOCH2CH2OCH3. A molybdenum acetylacetonate gel was prepared by addition of aqueous NH3. Thermal gravimetry (TG) and differential thermal analyses (DTA) of the gel suggested that crystallization of MoO3 occurs in a 140 K temperature range around 508°C. MoO3 films were prepared on fused silica, Si (111) and Al2O3 (012) substrates by annealing spin coating films of the sol in oxygen environment at 508°C. X-ray diffraction (XRD) showed that all films crystallize in -MoO3 structure, and crystallites on fused silica substrate are arbitrarily oriented while those on Si (111) and Al2O3(012) substrates oriented in the (010) direction. SEM investigations showed that MoO3 grains of all films are randomly distributed, with a longitudinal dimension of about 1–5 m and the film thickness is about 1 m.  相似文献   

2.
In this work we have analyzed the topography by atomic force microscopy (AFM) of dipalmitoyl-phosphatidyl-choline (DPPC) monolayers previously spread at the air–water interface and penetrated by β-casein. AFM images of β-casein–DPPC monolayers were taken from Langmuir–Blodgett films deposited onto hydrophilic mica substrates at different initial surface pressures (πi) and after the compression of the mixed films. The monolayer topography depends on the initial structure of the phospholipid:liquid expanded (LE) at 3 mN/m, coexistence between LE and liquid condensed (LC) structures at 7 mN/m, at the end of the LE–LC transition at 10 mN/m, and with a LC structure at 15 mN/m. The area occupied by DPPC domains in the mixed film increases with the πi value, especially for DPPC with a LC structure at 15 mN/m. At this surface pressure the thickness of the film is at a maximum. After the film compression at 25 mN/m, which is above the equilibrium spreading pressure of β-casein (), this protein is displaced from the interface by DPPC and the topography of the mixed monolayer depends on the initial structure of the DPPC monolayer. A notable feature of the topography of these mixed monolayers is the presence of multilayers of β-casein and DPPC of high thickness (50–70 nm) at the lower πi values. Although the film is dominated by DPPC at the highest surface pressures (at 25 mN/m), β-casein is not displaced totally from the interface and coexists as β-casein collapsed domains within the network of the DPPC structure.  相似文献   

3.
Chemical solution deposition method (CSD) method was used to prepare PbTiO3 (PT), Pb1– x Ca x TiO3 (PCT), PbTiO3-Al2O3 (PT-AL) and Pb1 – x Ca x TiO3-Al2O3 (PCT-AL) thin films on amorphous (soda-lime glass, SiO2 glass) substrates. The films were examined by XRD methods to describe the phase composition, cell parameters, type and degree of texture. In dependence on the molar ratio of Ti:Al, the different extent of crystallographic ordering was observed ranging from randomly oriented to strongly textured crystallites of PT. (100)uvw preferred orientation growth of PT grains was identified.  相似文献   

4.
Bismuth titanate films were fabricated onto highly oriented LaNiO3 electrode grown on SrTiO3(100) and LaAlO3(012) substrates using spin-coating technique with metal naphthenates as starting materials. (00l)/(h00)-oriented bismuth titanate films on LaNiO3/SrTiO3 and LaNiO3/LaAlO3 were obtained by pyrolysis at 500°C, followed by annealing at 750°C. In-plane alignment and surface morphology of the films analyzed by pole-figure analysis ( scanning) and field emission scanning electron microscope showed an imperfect epitaxy with polycrystalline structure.An erratum to this article can be found at  相似文献   

5.
BaTiO3 and PZT films were prepared from alkoxide-acetate solutions containing polyvinylpyrrolidone (PVP) by non-repetitive dip-coating. It was demonstrated that PVP incorporated in gel films suppresses crack formation during heating and increases the critical thickness, the maximum thickness achievable without crack formation via single-step deposition. Using PVP crack-free BaTiO3 and PZT films 1.2 and 0.5 m in thickness could be prepared, respectively, via single-step dip-coating. The films were fairly transparent and dense in microstructure. The tensile stress in heat-treated BaTiO3 films was also demonstrated to decrease significantly by incorporating PVP in gel films.  相似文献   

6.
TiO2 thin film photocatalysts coated onto soda lime glass were prepared by a dip coating process using a highly viscous solvent. The source of the TiO2 was tetraisopropyl orthotitanate, and -terpineol was used as the solvent. Two types of thin film preparation procedures based on dip coating (a sol-gel system and thermal decomposition system) were used to prepare the samples. TiO2 thin films were obtained after calcination at 450°C for 1 hour. The film thickness obtained with a single dipping was proportional to the viscosity of the dip coating solutions. The obtained thin films were transparent with a thickness of 1 m. The crystal form of the obtained photocatalyst films was anatase alone. The thin films were formed with aggregated nano-sized TiO2 single crystals (7–15 nm). The photocatalytic activity of the TiO2 thin films, as evaluated by the photooxidation of NO (1 ppm) in dry air, was as high as our previous TiO2 thin films prepared by the sol-gel method.  相似文献   

7.
The thermodynamic phase behavior and the morphology in thin films of poly(3-hexylthiophene) (P3HT) has been studied using calorimetry, X-ray scattering, and scanning force microscopy (AFM). Around 225 °C a phase transition from the crystalline state to a layered, liquid crystalline structure occurs in regioregular P3HT, while the regiorandom counterpart material is disordered at all temperatures and displays a glass transition temperature Tg–3 °C. Regioregular P3HT is semicrystalline and forms needle or plate like crystallites which in solution cast thin films are oriented with respect to the substrate. Films produced by spin coating display a non-equilibrium structure with reduced order and orientation. Annealing of these films in the liquid crystalline state leads to the formation of a morphology similar to the one observed in solution cast films.
T. Thurn-AlbrechtEmail:
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8.
Layers of Ni(DMG)2 and Ni(HAO)2 0.5-1 m thick were obtained by vacuum deposition. It was established by X-ray diffraction analysis (DRON-3M, DRON-SEIFERT-RM4, R = 192 mm, CuK radiation) that the layers are oriented polycrystalline films irrespective of the type of support used. Structural organization of the films and molecular orientations relative to the support surface were analyzed based on crystal data.  相似文献   

9.
In this study, we prepared Sr x Ba1 – x Nb2O6 (x = 0.3, 0.5 and 0.7) thin film on 0.75 wt% La doped SrTiO3 (100) and (110) single crystal substrates. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)5 as raw materials, and acetic acid and diethlene glycol monomethyl ether as solvents. The substrates were coated with the solution by spin coating method. As-coated thin films were heated from 973 to 1273 K in air. The grains of the thin film on La doped SrTiO3 (100) were pillar shaped and arranged in right angle to each other. On the other hand, the grains of these thin films on La doped SrTiO3 were pillar shape and arranged in one direction. The crystallographic relationship of the thin film between Sr x Ba1 – x Nb2O6 and substrate that the 130 and 310 direction of the thin film on the substrate were oriented with c-axis in parallel to the substrate surface. On the other hand, (hk0) phase diffractions of Sr x Ba1 – x Nb2O6 thin film on the substrate (110) were investigated in the XRD theta-2theta measurement. It is expected that the Sr x Ba1 – x Nb2O6 (x = 0.3, 0.5 and 0.7) were highly oriented or epitaxial growing on La doped SrTiO3 (110) single crystal substrate.  相似文献   

10.
TiO2 coating films of 0.3–0.4 m in thickness that contain fine Pd particles have been prepared by sol-gel method using Ti(OC3H 7 i )4 and PdCl2 as starting materials in an attempt to obtain optical materials that show surface plasma resonance in the visible range. A temperature higher than 900°C was required for formation of Pd metal particles when the heat-treatment was conducted in air. Heat-treatment of pre-heated amorphous films in air at 800°C resulted in precipitation of PdO particles, the size of which could be varied by changing the time of heat-treatment, and subsequent heat-treatment in H2/Ar gas converted the PdO particles into Pd metal particles. Heat-treatment of pre-heated amorphous films in H2/Ar gas also resulted in precipitation of Pd metal particles. The size of the Pd metal particles precipitated in the films was 6 to 90 nm, depending on the conditions of heat-treatment. The resultant TiO2 films containing Pd metal particles were brownish grey in color and showed optical absorption in the visible range over 400 nm, which is attributed to surface plasma resonance of Pd metal particles.  相似文献   

11.
Preparation of PZT Thick Films by an Interfacial Polymerization Method   总被引:3,自引:0,他引:3  
Pb(Zr0.53Ti0.47)O3 (PZT) films of 10 to 50 m in thickness were prepared by a new sol-gel process using an interfacial polymerization technique. The interfacial polymerization process is that an alkoxide precursor solution is poured on the surface of water in a container to form a gel film at the interface between the two immiscible liquids. The precursor solution was prepared by adding PZT alkoxide solution, PZT powders coated with Pb5Ge3O11 (PG), and a surfactant into hexane solvent. After the polymerization at the interface, the gel films were gently placed on a silicon substrate by draining the water in the container. The gel films containing PZT powders were sintered at 950°C for 10 min to obtain crystallized PZT films. The remanent polarization of a PZT thick film was 33.1 C/cm2. The piezoelectric d 33 constant measured with a Mach-Zehnder interferometer was 225 pm/V and was independent of frequency from 0.2 to 3 kHz.  相似文献   

12.
Homogeneous crack-free lead zirconate titanate (Pb(Zr0.45Ti0.55)O3: PZT 45/55) films were prepared by a chemically modified sol-gel process using lead acetate trihydrate, zirconium n-propoxide, and titanium isopropoxide precursors. The coating solutions were modified by the addition of diethanolamine. Single and multilayer films were deposited with a 2000 rpm spin rate on fused silica and MgO(100) substrates. Multiple spin coating with an intermediate heat treatment in air at 400°C for 3 min between coatings was performed to obtain films up to 2 m in thickness. The formation of the tetragonal perovskite structure was found to depend on the intermediate firing temperature, final annealing temperature, and annealing time. A 650°C rapid thermal annealing treatment in oxygen was required to crystallize the PZT film into the perovskite structure. The films were characterized using optical spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermo-gravimetry and differential scanning calorimetry (TG-DSC). The optical constants of the PZT films were evaluated from spectral transmittance and reflectance measurements. Optical constants are presented over the visible and near infrared region.  相似文献   

13.
The influence of the solvent on the thickness, morphology and structure of silica-polytetrahydrofuran hybrid films, prepared by spin coating, has been analysed. The inorganic precursor, tetraethylorthosilicate, was hydrolysed under acid catalysis, the hydrolysis molar ratio being 4. Polymers of average molecular weight (M n) 650 and 2900 were incorporated in the initial colloidal solutions, in a low concentration (organic/inorganic molar ratio 0.01). Two solvents were compared: ethanol, protic, and tetrahydrofuran, aprotic and a little less polar. The thickness and surface texture parameters of the films were determined by profilometry, their morphology characterized by SEM and their structure studied by FTIR. It is shown that the solvent has no effect on the molecular structure of the films, but strongly influences the surface texture and the morphology of both pure silica and hybrid films. The solutions prepared in tetrahydrofuran present shorter gelation times (t G) and allow the deposition of good quality films almost up to the gelation point (to a reduced time, t/t G, of 0.9). The films are thinner than those prepared from corresponding ethanolic solutions at the same reduced ageing times. For pure silica films, tetrahydrofuran is the best choice, since it reduces the fractured region on the edge of the substrate. For hybrid films, this effect is achieved by the polymer and tetrahydrofuran is responsible for a higher arithmetical mean roughness. Therefore, ethanol becomes the preferable solvent.  相似文献   

14.
Thin films of Zn-Ni-P on a copper substrate were synthesized by electrodeposition from chloride baths. It was found that the diffraction reflections of the crystal structure of Zn-Ni-P thin layers occur at thicknesses d ≥ 5 µm. The X-ray diffraction studies results confirm the formation in the Zn-Ni-P films of ZnNi10P3 compound. The morphology of the obtained films was analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The films are continuous and have a typical topography with many homogeneous globular features. EDS confirmed the formation of Zn-Ni-P coating only in 2 samples with Zn:Ni:P atomic ratios of 1:8:4 and 4:8:3, respectively. X-ray Photoelectron Spectroscopy (XPS) revealed the chemistry and the thickness of the studied thin films. At room temperature and thickness d ≥ 5 µm the investigated thin layers exhibit high values of the specific magnetizations in the range (25–37) A m2 kg?1, leading to the potential use in devices, appliances and electronics. The Curie temperature values of the synthesized Zn-Ni-P films were determined. It was found that by heating Zn-Ni-P thin layers of thicknesses d ≥ 5 µm up to a temperature T=900 K an interaction was detected with the copper substrate leading to a lower specific magnetization.   相似文献   

15.
A new method has recently been introduced for making detailed measurements of hydrodynamic effects in very thin liquid films between two surfaces. The method is used to obtain viscosity profiles, i. e. the viscosity as a function of the separation, between surfaces with adsorbed polymer layers. Results are presented for pure cyclohexane between two mica surfaces and for polystyrene (M w=9×105) adsorbed onto mica from cyclohexane at 26°C (i. e. below the-temperature of 34.5°C). The range of distances over which the concept of an effective hydrodynamic layer is applicable is established, and a simple correspondence is found between the effective hydrodynamic thickness, the radius of gyration of the polymer and the range of the steric force between the two polymer-covered surfaces. Further experimental evidence is presented which suggests that, depending on the solvent conditions, similar correlations apply more generally to other polymer systems.  相似文献   

16.
The discharge of thin films of Li x V2O5 is described by a mathematical diffusion model. The chemical diffusion coefficient for lithium ions, estimated with the model, is equal to (1.01–2.5) × 10–11 cm2/s. As the film thickness increases, the discharge capacity at a current of 20 A/cm2 tends to the calculated limiting of 3.12 C/cm2. The optimum thickness of the film electrode calculated for a discharge current of 20 A/cm2 is 33.4 m and agrees satisfactorily with the experimental value.  相似文献   

17.
In the present study n-type and p-type transparent conductive TiO2 films were prepared by using sol-gel method. The n-type TiO2 films were obtained by using Ti(OC3H 7 i )4 solutions co-doped with Ru and Ta. The films were uniform and transparent in all the conditions, and their crystalline phases were anatase when HCl or HNO3 was used as a catalyst. The resistivity decreased with increasing Ta content and increased with increasing Ru content. Most of the films showed resistivity minima at a heat-treatment temperature of 700°C. The lowest resistivity of 101 102 cm was attained. The p-type TiO2 films were obtained by using Ti(OC3H 7 i )4 solutions co-doped with Co and Nb (Sb). The films were also uniform and transparent when AcAc was used, while samples heat-treated at 800°C became opaque when HCl was added. Rutile single phase appeared when the films were heat-treated at 700°C. Logarithmic resistivity of films co-doped with Co and Nb was directly proportional to the reciprocal absolute temperature. On the other hand, the slopes for films co-doped with Co and Sb were different below and above 200°–220°C. The activation energy at the low-temperature region is as low as 0.17 eV, and the resistivity at room temperature is 104 105 cm.  相似文献   

18.
The depth dependence of Raman spectra of a-GeS2-type films having a different optical thickness (/4 and /2) and their refractive index profile have been investigated. The model of a layered-inhomogeneous structure of films has been proposed. There have been distinguished three regions: near-surface region (up to 50 Å), central part and transition film-substrate region (up to 300 Å).  相似文献   

19.
The bis(-diimino-tetracyano-pyrrolizinido)-Cu(II) complex (CuL2) has been incorporated in polystyrene (0.28% w/w), by evaporating tetrahydrofuran solutions either at room temperature (a) or at 100°C (b). From IR and UV-vis measurements and optical microscopy on the resulting films (a orb, thickness 50 m) it is concluded that CuL2 is present as a concentrated (C10–1 M) THF solution ina and as small solid particles (diameter <1 m) inb. The difference in colour of the films (dark bluea, light blueb), due to the different physical state of CuL2 in the matrix, is expected, and has been preliminarily shown using similar films based on NiL2, to be useful for sensing organic vapours in the atmosphere.  相似文献   

20.
Niobium-modified lead zirconate titanate thin films (PNZT) with nominal compositions, Pb(1–0.5x) (Zr0.53 Ti0.47)1–x Nb x O3:x = 0.02–0.07, have been prepared using a diol based sol-gel route. Single-layer (0.5 m) films were fabricated on platinised silicon substrates by spin-coating. The effect of niobium additions with regard to phase development, microstructure, and ferroelectric and dielectric properties were investigated for different annealing temperatures. For comparison, unmodified PZT films were also prepared. Niobium substitution increased the crystallisation temperatures for perovskite PNZT phase formation. The values of remanent polarisation P r and dielectric constant r were found to decrease with the introduction of Nb. For example, in films heated at 700°C for 15 min, the P r value of an unmodified PZT film was 31 C cm–2, compared to 17 C cm–2 for an x = 0.05 PNZT film, whilst respective relative permittivity values fell from 1190 to 600. The highest Nb concentration film, x = 0.07, did not display any switchable polarisation characteristics, which is consistent with high levels of intermediate pyrochlore phase.  相似文献   

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