Search results for " solution"
showing 10 items of 3084 documents
Polymorphism and the glasslike state of cyanide mixed crystals: A mesoscopic problem.
1990
The martensitic aspect of the structural phase transitions of the alkali cyanides and their solid solutions with the alkali halides is discussed. It is suggested that the polymorphism is intimately connected with the problem of mesoscopic transformation strains. At intermediate CN concentrations a competition between glasslike inhomogeneous strains, modulated strains, and ferroelastic strains is observed.
Quantum chemical modelling of perovskite solid solutions
2000
In line with our previous study (Eglitis R I et al 1998 J. Phys.: Condens. Matter 10 6271) for a single Nb impurity and Nb clusters in KTaO3 we present here the results of calculations for a series of perovskite KNbx Ta 1−x O3 (KTN) solid solutions (x = 0, 0.125, 0.25, 0.75, and 1). The quantum chemical method of the intermediate neglect of the differential overlap (INDO) combined with the large unit cell (LUC) periodic model is used. According to the INDO calculations, Nb impurity becomes off-centre in KTaO3 already at the lowest studied Nb concentration. Its off-centre displacement is in a good agreement with XAFS measurements. We compare our results with previous FP-LMTO calculations. Pe…
Phononic heat transport in the transient regime: An analytic solution
2016
We investigate the time-resolved quantum transport properties of phonons in arbitrary harmonic systems connected to phonon baths at different temperatures. We obtain a closed analytic expression of the time-dependent one-particle reduced density matrix by explicitly solving the equations of motion for the nonequilibrium Green's function. This is achieved through a well-controlled approximation of the frequency-dependent bath self-energy. Our result allows for exploring transient oscillations and relaxation times of local heat currents, and correctly reduces to an earlier known result in the steady-state limit. We apply the formalism to atomic chains, and benchmark the validity of the approx…
Validation of liposomal lipid composition by thin-layer chromatography.
2012
Liposomes of different sizes are frequently used model systems for cellular membranes. To mimic the cellular environment, these liposomes are often prepared from a mixture of different lipids in organic solution. The preparation involves, at some point, the transfer into aqueous solution. Thus, both the total amount of lipid and the relative amount of each lipid species might deviate from the original composition in the organic solvent. We used thin-layer chromatography combined with a lipid extraction step to check whether the liposomes in the final aqueous solution have the intended composition. This allows determination of the lipid composition not only for large unilamellar vesicles, bu…
A quantitative method of photoadsorption determination for irradiated catalyst in liquid–solid system
2009
WOS: 000266963000002
Control on the morphology and photoelectrocatalytic properties of ZnO nanostructures by simple anodization varying electrolyte composition
2021
Abstract Zinc oxide nanostructured electrodes were successfully synthesized by a simple method of anodization in different aqueous bicarbonate electrolytes. The influence of the anodization electrolyte composition (by adding ethanol or glycerol) on the morphology and the photoelectrocatalytic properties of the zinc oxide electrodes was studied, as well as the combined effect of anodizing under controlled hydrodynamic conditions. Field Emission Scanning Electron Microscope (FE-SEM) images of the ZnO electrodes showed that the addition of ethanol or glycerol to the anodization electrolyte resulted in changes in size and morphology of the nanostructures. Thus, ZnO nanowires, nanotubes, nanospo…
The influence of nitrogen incorporation on the optical properties of anodic Ta2O5
2012
Abstract Anodic oxides were grown on sputter-deposited Ta in different aqueous solutions. A photoelectrochemical investigation was performed in order to estimate the band gap of the films as a function of the anodizing bath composition and formation voltage, i.e. thickness. Photoelectrochemical results provided evidence of sub-band gap photocurrent for films formed in a bath containing ammonium ions at pH 9. Elemental depth profiles obtained by glow discharge optical emission spectroscopy revealed the presence of nitrogen species in the outer part of the anodic films, which is bonded to Ta according to XPS analysis. A mechanism of nitrogen incorporation is proposed in order to account for t…
Enhancement of visible light photoelectrocatalytic activity of ZnO(core)/TiO2(shell) composite by N-doping and decorating with Au0 nanoparticles
2017
Abstract The composites consisting of ITO-supported ZnO nanorods covered with TiO2 shell were doped with nitrogen and decorated with gold nanoparticles in order to improve their photocatalytic activity under visible light. N-doped TiO2 (TiO2(N)) was prepared under mild conditions through a simple sol-gel synthesis in the presence of NH4Cl. Such procedure results in formation of a highly porous shell of TiO2(N) on the ZnO nanorods. The gold nanoparticles (AuNPs) of the size 7–25 nm were grafted onto the surface of TiO2 as well as TiO2(N) by a photodeposition method from aqueous solution of [AuCl(4-x)(OH)x]− precursor at pH 6.7. The composition and microstructure of the prepared samples were …
Photoelectrochemical study of electrochemically formed semiconducting yttrium hydride (YH3−x)
1999
Abstract The first photoelectrochemical study of semiconducting YH 3− x films formed by etching bulk Y metal in 0.5 M H 2 SO 4 solution is reported. The formation of semiconducting hydride having an indirect optical band gap, E g opt , of about 2.35 eV is confirmed by in situ photocurrent spectroscopy. The photoelectrochemical behaviour of such a phase was investigated both in alkaline and in acidic solutions. The flat band potential was estimated to be U fb =−1.25 V/NHE, independent of pH.
Photoelectrochemical Evidence of Cu2O/TiO2 Nanotubes Hetero-Junctions formation and their Physicochemical Characterization
2014
Cu2O/TiO2 nanotubes heterojunctions were fabricated by electrochemical deposition of cuprous oxide on TiO2 nanotubes arrays grown by anodizing. X-ray diffraction and Raman Spectroscopy analysis allows for identification of Cu2O, whose morphological features were studied by Scanning Electron Microscopy as a function of the charge circulated during the electrodeposition step. Photoelectrochemical measurements in aqueous solutions evidenced a red shift of the light absorption threshold of TiO2 nanotubes due to the presence of cuprous oxide even for very low circulated charges, while electrochemical impedance measurements proved a significant reduction of the electrode impedance due the presenc…