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1.
SnO2-TiO2 composite thin films were fabricated on soda-lime glass with sol-gel technology. By measuring the contact angle of the film surface and the degradation of methyl orange, we studied the influence of SnO2 doping concentration, heat-treatment temperature and film thickness on the super-hydrophilicity and photocatalytic activity of the composite films. The results indicate that the doping of SnO2 into TiO2 can improve their hydrophilicity and photocatalytic activity, and the composite film with 1-5 mol% SnO2 and heat-treated at 450°C is of super-hydrophilicity. The optimal SnO2 concentration for the photocatalytic activity is 10 mol% and larger film thickness is helpful to reduce the contact angle of the composite films. 相似文献
2.
Sébastien Saitzek Frédéric Guinneton Laurent Sauques Jean-Raymond Gavarri 《Thin solid films》2008,516(6):891-897
Thermochromic VO2 thin films presenting a phase change at Tc = 68 °C and having variable thickness were deposited on silicon substrates (Si-001) by radio-frequency sputtering. These thin films were obtained from optimized reduction of low cost V2O5 targets. Depending on deposition conditions, a non-thermochromic metastable VO2 phase might also be obtained. The thermochromic thin films were characterized by X-ray diffraction, atomic force microscopy, ellipsometry techniques, Fourier transform infrared spectrometry and optical emissivity analyses. In the wavelength range 0.3 to 25 μm, the optical transmittance of the thermochromic films exhibited a large variation between 25 and 100 °C due to the phase transition at Tc: the contrast in transmittance (difference between the transmittance values to 25 °C and 100 °C) first increased with film thickness, then reached a maximum value. A model taking into account the optical properties of both types of VO2 film fully justified such a maximum value. The n and k optical indexes were calculated from transmittance and reflectance spectra. A significant contrast in emissivity due to the phase transition was also observed between 25 and 100 °C. 相似文献
3.
Thin films of nanocrystalline SnS2 on glass substrates were prepared from solution by dip coating and then sulfurized in H2S (H2S:Ar = 1:10) atmosphere. The films had an average thickness of 60 nm and were characterized by X-ray diffraction studies, scanning electron microscopy, EDAX, transmission electron microscopy, UV-vis spectroscopy, and Raman spectroscopy. The influence of annealing temperature (150-300 °C) on the crystallinity and particle size was studied. The effect of CTAB as a capping agent has been tested. X-ray diffraction analysis revealed the polycrystalline nature of the films with a preferential orientation along the c-axis. Optical transmission spectra indicated a marked blue shift of the absorption edge due to quantum confinement and optical band gap was found to vary from 3.5 to 3.0 eV with annealing temperature. Raman studies indicated a prominent broad peak at ∼314 cm−1, which confirmed the presence of nanocrystalline SnS2 phase. 相似文献
4.
S.H. Hu J. Chen Z.G. Hu G.S. Wang X.J. Meng J.H. Chu N. Dai 《Materials Research Bulletin》2004,39(9):1223-1229
Bi3.25La0.75Ti3O12(BiLT) thin films with different thickness were successfully deposited onto fused quartz by chemical solution deposition. X-ray diffraction analysis shows that BiLT thin films are polycrystalline with (0 0 2)-preferred orientation. The dispersion of refractive indices of the BiLT thin films was investigated by the optical transmittance spectrum. The optical band gap energy was estimated from the graph of (hνα)2 versus hν. The results show that the refractive index and band-gap energy of the BiLT thin films decrease with the films thickness. 相似文献
5.
Alumina (Al2O3) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al2O3-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed. 相似文献
6.
Shao Wei Wang Wei LuNing Li Zhi Feng LiHong Wang Min WangXue Chu Shen 《Materials Research Bulletin》2002,37(10):1691-1697
Crack-free Bi2Ti2O7 thin films on silicon substrates were prepared using chemical solution decomposition technique, and then treated by rapid thermal annealing. The microstructure of the films was studied by scanning electron microscopy. The effects of different fabricating procedures and various annealing temperatures and times on the leakage current density were investigated. The results show that the leakage current density decreases with increasing annealing temperature, while increases with increasing annealing time. Annealing temperature has a much stronger effect on the insulating properties of Bi2Ti2O7 thin films than that of annealing time. 相似文献
7.
S.S. Fouad G.B. Sakr I.S. Yahia D.M. Abdel Basset 《Materials Research Bulletin》2011,46(11):2141-2146
Stoichiometric thin film samples of the ternary ZnGa2Te4 defect chalcopyrite compound were prepared and characterized by X-ray diffraction technique. The elemental chemical composition of the prepared bulk material as well as of the as-deposited film was determined by energy-dispersive X-ray spectrometry. ZnGa2Te4 thin films were deposited, by conventional thermal evaporation technique onto highly cleaned glass substrates. The X-ray and electron diffraction studies revealed that the as-deposited and the annealed ZnGa2Te4 films at annealing temperature ta ≤ 548 K are amorphous, while those annealed at ta ≥ 573 K (for 1 h), are polycrystalline. The optical properties of the as-deposited films have been investigated for the first time at normal incidence in the spectral range from 500 to 2500 nm. The refractive index dispersion in the transmission and low absorption region is adequately described by the Wemple–DiDomenico single oscillator model, whereby, the values of the oscillator parameters have been calculated. The analysis of the optical absorption coefficient revealed an in-direct optical transition with energy of 1.33 eV for the as-deposited sample. This work suggested that ZnGa2Te4 is a good candidate in solar cell devices as an absorbing layer. 相似文献
8.
Capacitor-like Au/BiFeO3/SrRuO3 thin film with (1 1 1) orientation was grown on the SrTiO3 (1 1 1) substrate by radio frequency magnetic sputtering. It shows a resistive switching behavior, where a stable hysteresis in current–voltage curve was well developed by applying an optimum voltage at room temperature, and it reached the saturation at a bias voltage of 8 V. The Child's law in Vmax → 0 direction and the interface-limited Fowler–Nordheim tunneling in 0 → Vmax direction, together with the polarization reversal in the BiFeO3 barrier, are shown to involve in the observed resistive hysteresis. 相似文献
9.
Compact and grape-like bismuth oxide (Bi2O3) coated titania (Ti) anode was prepared by oxalic acid (H2C2O4) etching, electrodeposition and calcination in order to explore its photoelectrocatalytic activities. The Bi2O3 coating was demonstrated to be full of pores, and a good combination between Bi2O3 layer and honeycomb-like Ti substrate was observed by scanning electron microscopy. The characteristic morphology of Bi2O3 coating indicated that the electrode is stable during degradation. The Bi2O3/Ti electrode was used in oxidative degradation of Acid Orange 7 by electrolysis, photocatalytic oxidation and photoelectrocatalytic oxidation processes. The pseudo-first order kinetics parameter (Kapp) of photoelectrocatalytic process was 1.15 times of the sum of electrolysis and photocatalytic oxidation under visible light irradiation at 420 nm. The results indicated that the synergy of electrolysis and photocatalysis lead to an excellent photoelectrocatalytic property of the Bi2O3/Ti electrode. 相似文献
10.
Xian Ming Wu Xin Hai LiMing Fei Xu Yun He ZhangZe Qiang He Zhuo Wang 《Materials Research Bulletin》2002,37(14):2345-2353
Cathode material LiMn2O4 thin films were prepared by aqueous solution deposition using lithium acetate and manganese acetate as starting materials. The structures, morphologies, and the first discharge specific capacity of the thin films were investigated as a function of annealing temperature and time. The cycling properties of the thin films were also examined. The results show that LiMn2O4 thin films prepared by this method are homogenous and crack-free. The thin film annealed at 750°C for 30 min has good rechargeability. The capacity loss per cycle is about 0.05% after being cycled 100 times. 相似文献
11.
Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thin films with thickness of 500 nm were successfully deposited on TiO2 buffered Pt(1 1 1)/Ti/SiO2/Si(1 0 0) and Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates via sol-gel process. Microstructure of Pb0.97La0.02(Zr0.95Ti0.05)O3 thin films was studied by X-ray diffraction analyses. The antiferroelectric nature of the Pb0.97La0.02(Zr0.95Ti0.05)O3 thin films was confirmed by the double hysteresis behaviors of polarization and double buffer fly response of dielectric constant versus applied voltage at room temperature. The capacitance-voltage behaviors of the Pb0.97La0.02(Zr0.95Ti0.05)O3 films with and without TiO2 buffer layer were studied, as a function of temperature. The temperature dependence of dielectric constant displayed a similar behavior and the Curie temperature (Tc) was 193 °C for films on both substrates. The current caused by the polarization and depolarization of polar in the Pb0.97La0.02(Zr0.95Ti0.05)O3 films was detected by current density-electric field measurement. 相似文献
12.
Flower-like Y2O3 nano-/microstructured phosphors without metal activators have successfully been fabricated by an ionic liquid (IL)-assisted method involving temperature (600 °C) annealing. In this paper, the effect of IL concentration on the morphology of the product has been investigated. The IL plays a crucial role in the formation of various morphologies of Y2O3. The structural and morphological features of the obtained samples have been characterized by means of X-ray powder diffraction (XRD) analysis, photoluminescence spectra (PL), Fourier-transform infrared (FT-IR) spectra and X-ray photoelectron spectra (XPS). The photoluminescence spectra of the products exhibit an intense bluish-white emission (ranging from 405 to 430 nm and centered at 418 nm). The luminescent mechanisms have been ascribed to the carbon impurities in the Y2O3 host. The effect of the ILs cation and the counter anions on the Y2O3 morphology of these nanostructures was studied experimentally. It was observed that Y2O3 morphology and PL of these nanostructures were strongly influenced by the type of cation and anion. As the length of the subsidiary chain of cation section of IL (imidaziole ione) reduces, the thickness of the nano-sheets increases. It is expected that the present method may easily be extended to similar nano-/microstructures of other oxide materials. Such investigations are currently underway. 相似文献
13.
Meinan Liu 《Materials Research Bulletin》2010,45(3):333-338
Hollow micro-sized H2(H2O)Nb2O6 spheres constructed by nanocrystallites have been successfully synthesized via a bubble-template assisted hydrothermal process. In the reaction process, H2O2 acts as a bubble generator and plays a key role in the formation of the hollow structure. An in situ bubble-template mechanism has been proposed for the possible formation of the hollow structure. The spherelike assemblies of these H2(H2O)Nb2O6 nanoparticles have been transformed into their corresponding pseudohexagonal phase Nb2O5 through a moderate annealing dehydration process without destroying the hierarchical structure. Optical properties of the as-prepared hollow spheres were investigated. It is exciting that the absorption edge of the hollow Nb2O5 microspheres shifts about 18 nm to the violet compared with bulk powders in the UV/vis spectra, indicating its superior optical properties. 相似文献
14.
T. Zhang X.X. Huang B. Zhong X.D. Zhang H.W. Bai H.M. Yu 《Materials Research Bulletin》2010,45(7):779-782
A pure nickel coating has been successfully plated on the surface of ultra fine Al2O3 particles via a facile electroless plating method. Coating morphology and crystallite size can be tailored by pH values. Dense coating with the maximum crystallite size of 24 nm was obtained at pH 11.0 and porous coating with the minimum crystallite size of 15 nm was obtained at pH value 12.5. The plated powders have been demonstrated to be an effective catalyst for growing boron nitride nanotubes. 相似文献
15.
Francesca Mangiarini Adolfo Speghini Fiorenzo Vetrone 《Materials Research Bulletin》2010,45(8):927-932
In this study, monoclinic luminescent Gd2O3 nanocrystals doped with different concentrations of Er3+ (0.1, 1, and 10 mol%) were produced by propellant synthesis and flame spray pyrolysis (FSP). A comparison of their optical and morphological properties is reported. Following 980 nm excitation, an increase of the emission intensity from the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions was observed with increasing Er3+ concentration in the Gd2O3 nanocrystalline samples prepared via both techniques. However, the overall upconversion emission intensity was greater for the samples obtained by FSP. Furthermore, as the Er3+ concentration was increased, the intensity of the red (4F9/2 → 4I15/2) emission was observed to increase more rapidly in comparison to the green (2H11/2, 4S3/2 → 4I15/2) emission resulting in an overall enhancement of the red component in the upconversion emission. Although both synthetic routes yield average crystallite sizes in the nanoscale, the TEM and SEM images confirm a more homogeneous morphology and lower particle aggregation for the nanocrystals produced by FSP. 相似文献
16.
Jigui ChengShaowu Zha Xiaohong FangXingqin Liu Guangyao Meng 《Materials Research Bulletin》2002,37(15):2437-2446
Gadolinia doped ceria (Ce0.9Gd0.1O1.95, GDC) electrolyte films were tape cast from oxalate coprecipitated GDC powders, gelcast GDC powders and their mixtures, respectively, to evaluate the effects of the original particle size and distribution on the properties of the green and sintered GDC cast tapes. The apparent density of different original powders, as well as the green density, sintered behavior, and electrical conductivity of tapes cast from the various starting powders were investigated. Mixing the coprecipitated and the gelcast GDC powders not only results in a higher packing efficiency of particles in the loose powders, but also results in higher green and sintered densities of cast tapes. Furthermore, tapes cast from the 50/50 powder mixtures can be sintered to 96.2% of theoretical density at relatively low sintering temperature of 1400°C, whereas those from the oxalate coprecipitated and from the gelcast powders were only 89.7 and 94.1% dense, respectively. The ac impedance measurement shows that GDC films cast from the 50/50 powder mixture exhibit good electrical conductivity (4.2 and 6.0 S m−1 at 700 and 800°C in air, respectively). The test results have revealed that high-density GDC films can be fabricated by tape casting technique at relatively low sintering temperature by optimizing the particle size distribution of the starting powders. 相似文献
17.
S. Mula 《Materials Research Bulletin》2009,44(5):1154-4356
An investigation on the structure of an ultrasonically cast nanocomposite of Al with 2 wt.% nano-sized Al2O3 (average size ∼10 nm) dispersoids showed that the nanocomposite was consisting of nearly continuous nano-alumina dispersed zones (NDZs) in the vicinity of the grain boundaries encapsulating Al2O3 depleted zones (ADZs). The mechanical properties were investigated by nanoindentation and tensile tests. The nano-sized dispersoids caused a marginal increase in the elastic modulus, and a significant increase in the hardness (∼92%), and tensile strength (∼48%). Subsequent cold rolling to achieve a reduction ratio of 2 resulted in an appreciable increase in the hardness due to change in morphology of the microstructure. Estimation of the strength on the basis of inter-particle spacing, which was measured by transmission electron microscopy, could not be accounted for on the basis of Orowan mechanism, and therefore, strengthening mechanisms like local climb and/or cross slip might have a role in this room temperature (0.32TM) deformation process. 相似文献
18.
Bin He Jiangtao Li Liang Wu Zengchao Yang Shibin Guo Yixiang Chen 《Materials Research Bulletin》2011,46(7):1035-1038
Y2O3-Al2O3-SiO2 glasses were prepared by combustion synthesis melt-casting under high gravity. The properties of the glasses strongly depended on the starting compositions and preparation conditions. With a higher SiO2 content in the starting compositions, the glass-forming ability of the melt was improved, but the density and hardness of the prepared glasses decreased. Crystallization occurred more frequently for larger samples and by using quartz crucibles instead of graphite ones. By increasing the high-gravity factors, both the density and hardness of the samples were improved. It is proposed that enhancing the high-gravity field facilitates the removal of bubbles from the melt. 相似文献
19.
A.Z. Simões C.S. Riccardi A.H.M. Gonzalez J.A. Varela 《Materials Research Bulletin》2008,43(1):158-167
The film thickness dependence on the ferroelectric properties of lanthanum modified bismuth titanate Bi3.25La0.75Ti3O12 was investigated. Films with thicknesses ranging from 230 to 404 nm were grown on platinum-coated silicon substrates by the polymeric precursor method. The internal strain is strongly influenced by the film thickness. The morphology of the film changes as the number of layers increases indicating a thickness dependent grain size. The leakage current, remanent polarization and drive voltage were also affected by the film thickness. 相似文献
20.
Ferroelectric Ba(Sn0.15Ti0.85)O3 (BTS) thin films were deposited on LaNiO3-coated silicon substrates via a sol-gel process. Films showed a strong (1 0 0) preferred orientation depending upon annealing temperature and concentration of the precursor solution. The dependence of dielectric and ferroelectric properties on film orientation has been studied. The leakage current density of thin films at 100 kV/cm was 7 × 10−7 A/cm2 and 5 × 10−5 A/cm2 and their capacitor tunability was 54 and 25% at an applied field of 200 kV/cm (measurement frequency of 1 MHz) for the thin films deposited with 0.1 and 0.4 M spin-on solution, respectively. This work clearly reveals the highly promising potential of BTS compared with BST films for application in tunable microwave devices. 相似文献