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141.
The solubility of Al2(SO4)3 in H2SO4 at different concentrations was determined and showed a minimum at 95% w/v. Overall kinetic and potentiometric studies of Al anodising were performed in large ranges of concentrations of saturated H2SO4 solutions and current densities. During anodising quasi-steady-state supersaturation and unsaturation conditions for concentrations below and above 95% w/v dominate in the pore-filling solution affecting those in the oxide–electrolyte interface. Interface colloidal Al2(SO4)3 nanoparticles form occupying surface fractions increasing with salt concentration, supersaturation, field strength in the pore base surface and current density increase and temperature decrease. These control the mechanism and kinetics of growth and structural parameters of films and impose the growth of non-pitted uniform films up to current densities higher than in unsaturated baths, more effectively under supersaturation conditions. Well-defined peaks of structural parameters appear depending on thickness and current. Thus optimal regularly grown films of desired nanostructure and the introduction of new anodising technologies can be achieved. 相似文献
142.
S. Yu. Vassiliev A. I. Yusipovich Yu. E. Rogynskaya F. Kh. Chibirova A. M. Skundin T. L. Kulova 《Journal of Solid State Electrochemistry》2005,9(10):698-705
The difference in degradation behavior of titania-doped tin dioxide films is explained by a pronounced effect of the doping level on the film dispersity and fine distribution of titania. A two to three times decrease in nanoparticles sizes in the doped films compared with nanoparticles in SnO2 film (20–30 nm) is revealed by using scanning tunneling microscopy (STM). Such STM data (measured in ex situ configuration) combined with XRD and Mössbauer spectroscopy analysis confirm that the nanoparticles are composed of nanostructured heavily disordered SnO2 and TiO2 rutile solid solution or of amorphous phase containing both SnO2 and TiO2, the content of the crystalline and amorphous phases being approximately equal.
相似文献
S. Yu. VassilievEmail: |
143.
Youbao Ni Yanhua Tong Guixiang Qian Xianwen Wei 《Journal of solid state chemistry》2005,178(3):908-911
Hollow carbon nanospheres were obtained at 200 °C via a new reaction route, by using magnesium, hexachloroethane and aluminum trichloride as starting materials and benzene as solvent. The products were characterized with X-ray diffraction pattern, transmission electron microscope, high-resolution transmission electron microscope images and Raman spectrum. The reaction conditions are easy to be maintained and controlled. They may provide a new method to produce other carbonaceous materials. A possible mechanism of reaction was proposed. 相似文献
144.
Huaiyu Shao 《Journal of solid state chemistry》2005,178(7):2211-2217
We successfully synthesized Mg2Cu alloys from the metal nanoparticles, which are produced from hydrogen plasma-metal reaction method, in two ways. One is under 0.1 MPa argon at 673 K and the other is under 4.0 MPa hydrogen at 673 K. The structure, morphology and reaction mechanism were studied. The hydrogen absorption and the pressure-composition isotherm properties of the obtained Mg2Cu alloy under hydrogen were studied. The van’t Hoff equation and the formation enthalpy and entropy of the resulting hydride (MgH2+MgCu2) were obtained from the equilibrium plateau pressures of the desorption isotherms. Nanostructured Mg2Cu shows excellent hydrogen storage properties because nanostructured materials have more surface area and more defects, which means more nucleation sites with hydrogen, and smaller particles, which means shorter diffusion distance for hydrogen in the alloys particles. 相似文献
145.
Synthesis and characterization of flowerlike ZnO nanostructures via an ethylenediamine-meditated solution route 总被引:1,自引:0,他引:1
Flowerlike ZnO nanostructures were deposited on Si substrate by choosing hexamethylenetetramine as the nucleation control reagent and ethylenediamine as the chelating and capping reagent. Structural and optical measurements reveal that obtained ZnO exhibits well-defined flowerlike morphology, hexagonal wurtzite structure, uniform distribution on substrate, and strong photoluminescence in ultraviolet band. The well-arrayed pedals of each ZnO flower possess the typical tapering feature, and are built up by many well-aligned ZnO nanorods. Moreover, each single nanorod building up the pedal exhibits the single crystal nature and the growth direction along c-axis. Effects of the precursor composition on the morphology of ZnO were discussed. 相似文献
146.
We have studied the high-pressure structural behavior of zinc ferrite (ZnFe2O4) nanoparticles by powder X-ray diffraction measurements up to 47 GPa. We found that the cubic spinel structure of ZnFe2O4 remains up to 33 GPa and a phase transition is induced beyond this pressure. The high-pressure phase is indexed to an orthorhombic CaMn2O4-type structure. Upon decompression the low- and high-pressure phases coexist. The compressibility of both structures was also investigated. We have observed that the lattice parameters of the high-pressure phase behave anisotropically upon compression. Further, we predict possible phase transition around 55 GPa. For comparison, we also studied the compression behavior of magnetite (Fe3O4) nanoparticles by X-ray diffraction up to 23 GPa. Spinel-type ZnFe2O4 and Fe3O4 nanoparticles have a bulk modulus of 172 (20) GPa and 152 (9) GPa, respectively. This indicates that in both cases the nanoparticles do not undergo a Hall-Petch strengthening. 相似文献
147.
Dr. Yongzheng Xing Dr. Alexia Rottensteiner Dr. Jonah Ciccone Prof. Stefan Howorka 《Angewandte Chemie (International ed. in English)》2023,62(33):e202303103
Membrane-spanning nanopores are used in label-free single-molecule sensing and next-generation portable nucleic acid sequencing, and as powerful research tools in biology, biophysics, and synthetic biology. Naturally occurring protein and peptide pores, as well as synthetic inorganic nanopores, are used in these applications, with their limitations. The structural and functional repertoire of nanopores can be considerably expanded by functionalising existing pores with DNA strands and by creating an entirely new class of nanopores with DNA nanotechnology. This review outlines progress in this area of functional DNA nanopores and outlines developments to open up new applications. 相似文献
148.
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150.
L. Radonjić M. Todorović J. Miladinović 《Journal of Sol-Gel Science and Technology》2008,45(2):125-132
Ferroelectric nanostructured barium titanate (BT) thin films derived by a modified sol–gel process were formed by a deep coating
method on Si (100) substrate. In this work was investigated the influence of different types and amounts of water (free water
directly added in process and crystalline water from barium precursors) and of different barium precursors (hydroxide and
acetate) on the gel-structure evolution and the barium titanate thin film crystallization. The IR-spectroscopy and X-ray diffraction
analysis were used for sample characterization. Experimental results show that crystalline water from barium hydroxide octahydrate
stabilizes the cubic phase of barium titanate. Barium titanate crystallizes in the tetragonal form in thin films when sols
were prepared with free water and Ba-acetate or Ba-hydroxide monohydrate as precursors. The type of Ba-precursor used in preparation
of sols effects the rate of crystallization of the BT in thin films, making it slower in the case when as precursor was used
Ba-acetate than Ba-hydroxides. The prepared BT-thin films demonstrated good adhesion towards substrate and were smooth and
uniform. 相似文献