共查询到16条相似文献,搜索用时 15 毫秒
1.
Effect of La doping on microstructure of SnO2 nanopowders prepared by co-precipitation method 总被引:3,自引:0,他引:3
A series of La-doped SnO2 nanopowders with various dopant concentrations were prepared by chemical co-precipitation technique, and the nanopowders prepared were characterized by differential scanning calorimeter (DSC), thermo-gravimetric (TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that La doping can obviously prevent the growth of nanosized SnO2 crystallites. When the La concentration reaches and surpasses 5 at.%, SnO2 crystallite size reaches a minimum value and remains almost constant. With the increase of La concentration, La tends to dissolve in the bulk phase of SnO2 to form solid solution below 10 at.% addition and then starts to disperse onto the surface of the solid solution as a monolayer above 10 at.%. The effect of La doping on hindering crystallite growth can be attributed to the solute drag and lattice distortion resulting from La dissolving in the bulk phase of SnO2 to form solid solution, rather than the monolayer of La on the surfaces of the SnO2 powders. 相似文献
2.
Z. Essalhi B. Hartiti A. Lfakir M. Siadat P. Thevenin 《Molecular Crystals and Liquid Crystals》2016,627(1):148-152
ABSTRACTTiO2:SnO2 thin films were deposited on glass substrates, by using sol gel spin coating method with different ratio (3%, 5% and 7%) at 3200 rpm, to study their effect on different properties of TiO2: SnO2 thin films. The structural and optical properties of films have studied for different ratio. These deposited films have been characterized by various methods such as X-Ray Diffraction (XRD), Ultra Visible spectroscopy. The (XRD) can be used to identify crystal structure of as deposited films. The Transmission spectra have shown the transparent and opaque parts in the visible and UV wavelengths. 相似文献
3.
Tae Sung Eom Kyung Hwan Kim Chung Wung Bark 《Molecular Crystals and Liquid Crystals》2014,600(1):39-46
In this work, we report for the first time the improvement of the photovoltaic characteristics of dye-sensitized solar cells (DSSCs) by doping TiO2 with Fe2O3. DSSCs were fabricated using various percentages of Fe2O3-doped TiO2 composite nanoparticles. The Fe2O3-doped DSSCs exhibited a maximum conversion efficiency of 5.76% because of the effective electron transport. DSSCs based on Fe2O3-doped TiO2 films showed better photovoltaic performance than cells fabricated with only TiO2 nanoparticles. This result was attributed to the prevention of recombination between electrons in the TiO2 conduction band with the dye or electrolytes. A mechanism was suggested based on impedance results, which indicated improved electron transport at the interface of the TiO2/dye/electrolyte. 相似文献
4.
N. Baizura 《Journal of Non》2011,357(15):2810-2815
Tellurite 75TeO2-(10 − x)Nb2O5-15ZnO-(x)Er2O3; (x = 0.0-2.5 mol%) glass system with concurrent reduction of Nb2O5 and Er2O3 addition have been prepared by melt-quenching method. Elastic properties together with structural properties of the glasses were investigated by measuring both longitudinal and shear velocities using the pulse-echo-overlap technique at 5 MHz and Fourier Transform Infrared (FTIR) spectroscopy, respectively. Shear velocity, shear modulus, Young's modulus and Debye temperature were observed to initially decrease at x = 0.5 mol% but remained constant between x = 1.0 mol% to x = 2.0 mol%, before increasing back with Er2O3 addition at x = 2.5 mol%. The initial drop in shear velocity and related elastic moduli observed at x = 0.5 mol% were suggested to be due to weakening of glass network rigidity as a result of increase in non-bridging oxygen (NBO) ions as a consequence of Nb2O5 reduction. The near constant values of shear velocity, elastic moduli, Debye temperature, hardness and Poisson's ratio between x = 0.5 mol% to x = 2.0 mol% were suggested to be due to competition between bridging oxygen (BO) and NBO ions in the glass network as Er2O3 gradually compensated for Nb2O5. Further addition of Er2O3 (x > 2.0 mol%) seems to further reduce NBO leading to improved rigidity of the glass network causing a large increase of ultrasonic velocity (vL and vS) and related elastic moduli at x = 2.5 mol%. FTIR analysis on NbO6 octahedral, TeO4 trigonal bipyramid (tbp) and TeO3 trigonal pyramid (tp) absorption peaks confirmed the initial formation of NBO ions at x = 0.5 mol% followed by NBO/BO competition at x = 0.5-2.0 mol%. Appearance of ZnO4 tetrahedra and increase in intensity of TeO4 tbp absorption peaks at x = 2.0 mol% and x = 2.5 mol% indicate increase in formation of BO. 相似文献
5.
A sol-gel method was used to prepare CaO-B2O3-SiO2 (CBS) glass powder for making low-temperature cofired ceramics. This paper was focused on the mechanism of hydrolysis and polymerization and also on the structural evolution of xerogel at various temperatures. The xerogel was transformed into glass ceramics containing CaSiO3 and CaB2O4 crystalline phases through nucleation and crystallization processes. The results indicated that the xerogel exhibits [BO4] or [SiO4] based three-dimensional network structure whose interstices Ca ions fill in, which becomes more orderly and stable after heat treatments. The CBS glass ceramics through controlled crystallization have a potential as electronic packaging materials. 相似文献
6.
An important question in the manufacture of superconducting electronics is how to control the two-level systems found in amorphous insulators. The present article shows that hydrogen has a marked impact on the two-level systems in thin films of reactively sputtered Al2O3, a standard tunnel oxide for Josephson junctions. The magnitude of dielectric relaxation current in Al2O3 films, believed to be caused by two-level systems, is shown to increase monotonically with the flow rate of H2 into the chamber during deposition. This points toward a potential need for controlling hydrogen during the manufacture of superconducting electronics utilizing Al2O3. 相似文献
7.
H. Doweidar 《Journal of Non》2011,357(7):1665-1670
Data of density, refractive index and thermal expansion coefficient for B2O3-SiO2 and GeO2-SiO2 glasses have been analyzed. The volumes of the structural units are the same found for the vitreous B2O3, GeO2 and SiO2. The volume of any structural unit is constant over the entire composition region of the glass system. The same has been found for the differential refraction and unit refraction of the structural units in these glasses. Different features are observed for the differential expansion of the structural units. There is a considerable change with composition in the differential expansion of BO3, GeO4 and SiO4 units. The effect is attributed to a change in the asymmetry of vibrations with the number of Si-O-B or Si-O-Ge linkages in the matrix. The thermal expansion coefficient is mainly determined by the contribution of B2O3 or GeO2 in the concerned glasses. 相似文献
8.
Satoru Utsugi Yoshitaka Ehara Hidenori Tanaka Tomoaki Yamada Hiroshi Funakubo Hiroshi Uchida 《Journal of Crystal Growth》2010,312(21):3127-3130
Epitaxial (La0.07Sr0.93)SnO3 [LSSO] films were deposited on CaF2 substrates by pulse laser deposition. The (1 0 0)c orientation of LSSO films was observed only on (1 1 0)CaF2, whereas (1 1 0)c orientation was found on (1 1 1)CaF2 and (1 0 0)CaF2. (0 0 1) polar axis oriented tetragonal Pb(Zr0.35Ti0.65)O3 films were grown on the fabricated (1 0 0)cLSSO∥(1 1 0)CaF2 by pulsed metal organic chemical vapor deposition. The (0 0 1)Pb(Zr0.35Ti0.65)O3∥(1 0 0)cLSSO∥(1 1 0)CaF2 stack structure exhibited about 70% transparency with an adsorption edge of approximately 330 nm. 相似文献
9.
Hiroshi Negishi Saiko Negishi Minoru Sasaki Masasi Inoue Shigeo Ohara 《Molecular Crystals and Liquid Crystals》2013,570(2):63-68
Abstract EXAFS and XANES spectra of Ti K-edge have been measured for 3d transition metal intercalation compounds M x TiS2 (M = Mn, Fe, Co and Ni; x ≤ 0.33). We have found that the interatomic distance between Ti and the first nearest neighbor S atoms, R(Ti-S), increases with the guest concentration x. The variation in XANES spectra with x reveals the reduction of the valence state of Ti atoms upon intercalation of M. From these results as well as the M K-edge EXAFS data studied previously, we have proposed a simple model on the local structure of M x TiS2 to reproduce the observed values of R(Ti-S) by averaging local shift of S atoms caused by intercalation. 相似文献
10.
Abstract [Na(H2O)2(C18H15O6SO3)]2 was synthesized by sulfated 5-hydroxy-6,7,4′-trimethoxyisoflavone with concentrated sulfuric acid. Single-crystal X-ray diffraction
study indicates that it is a dimeric centrosymmetric species. The coordination polyhedron of each Na(I) atom exhibits a distorted
trigonal bipyramidal geometry. The dimeric units are linked by intermolecular hydrogen bonds C–H⋯π, C–H⋯O and O–H⋯O to result
in a three-dimensional framework.
Graphical Abstract [Na(H2O)2(C18H15O6SO3)]2 was synthesized by sulfated 5-hydroxy-6,7,4′-trimethoxyisoflavone with concentrated sulfuric acid. The coordination polyhedron
of each Na(I) atom exhibits a distorted trigonal bipyramidal geometry. The dimeric centrosymmetric units are linked by intermolecular
hydrogen bonds C–H⋯π, C–H⋯O and O–H⋯O to result in a three-dimensional framework.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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12.
The pseudo-binary NdBa2Cu3Ox–Ba3Cu10O13 phase diagrams and the crystallization of NdBa2Cu3Ox have been in situ observed using high-temperature optical microscope under three different oxygen atmospheres namely 1%, 0.1% and 0.0097% oxygen in argon. It has been observed that the liquidus line becomes narrower both in composition and temperature with decreasing oxygen pressure. This result suggested that under reduced oxygen atmosphere, the NdBa2Cu3Ox crystals could only be grown from a peritectic melt consisting of Nd4Ba2Cu2O10 and liquid. The crystallization temperature of NdBa2Cu3Ox was found to decrease logarithmically with decreasing oxygen content in the atmosphere. 相似文献
13.
Polydimethylsiloxane (PDMS)-based organic-inorganic hybrids have been studied because of their high dielectric strength, heat resistivity, and flexibility. In this study, we fabricated Al2O3 coatings on metal substrates with sufficient electrical insulation, heat conductivity, and thermal stability by electrophoretic deposition (EPD) using PDMS-based hybrid binders. The scratch hardness, thermal conductivity, and electrical breakdown strength of the Al2O3 coating before and after heat treatment at 300 °C for 500 h were 2.0 N, 3.1 W/mK, and 60 kV/mm, respectively. These results demonstrate the usefulness of EPD using PDMS-based hybrid binders for fabricating flexible heat dissipative substrates used in high-temperature environments. 相似文献
14.
Ti5Si3 thin films were coated on glass substrate by atmospheric pressure chemical vapor deposition method at different temperatures. Electrical and corrosion properties of the thin films were investigated. The results show that the electrical resistivity of the thin films decreases initially with the increase in deposition temperature. However, it increases with the further increase of the temperature. The lowest electrical resistivity of 107 μΩ⋅cm is obtained at 710 °C. The least corrosion rates of the thin films at 95 °C of 0.10 nm/min and 0.13 nm/min in 1 N and 10 N acid solution and of 0.33 nm/min and 6.55 nm/min in 1 N and 10 N alkali solution, respectively, are obtained by weight-loss measurement method. The corrosion mechanisms of the thin films were also discussed in detail. 相似文献
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