Henryk Drozdowski

The effect of Cu doping on the mechanical and optical properties of zinc oxide nanowires synthesized by hydrothermal route

Zinc oxide (ZnO) is a wide-bandgap semiconductor material with applications in a variety of fields such as electronics, optoelectronic and solar cells. However, much of these applications demand a reproducible, reliable and controllable synthesis method that takes special care of their functional properties. In this work ZnO and Cu-doped ZnO nanowires are obtained by an optimized hydrothermal method, following the promising results which ZnO nanostructures have shown in the past few years. The morphology of as-prepared and copper-doped ZnO nanostructures is investigated by means of scanning electron microscopy and high resolution transmission electron microscopy. X-ray diffraction is used to study the impact of doping on the crystalline structure of the wires. Furthermore, the mechanical properties (nanoindentation) and the functional properties (absorption and photoluminescence measurements) of ZnO nanostructures are examined in order to assess their applicability in photovoltaics, piezoelectric and hybrids nanodevices. This work shows a strong correlation between growing conditions, morphology, doping and mechanical as well as optical properties of ZnO nanowires.

X-ray diffraction studies of molecular correlations in liquid phenylcyclohexane

Abstract This paper reports results of the X-ray diffraction using CuK α radiation of liquid phenylcyclohexane at room temperature. An angular distribution of X-ray scattered intensity was measured. The electron-density radial-distribution function was numerically found using Fourier analysis. Structural parameters, the mean distances between the neighbouring molecules and the mean coordination numbers were found. A simple model of local arrangement of the molecules in liquid phenylcyclohexane was proposed.

Nanostructured zinc oxide systems with gold nanoparticle pattern for efficient light trapping

In this work we describe the design of a system consisting of a zinc oxide nanowire array and ITO glass nanostructured with gold NPs. Our goal was to create a more efficient system that could be used in various optical applications, such as photovoltaics or photodetectors. The impact of gold NPs of different shapes, single as well as arranged in a pattern, on the optical properties of the system was studied by using a finite integration technique. The absorptance and transmittance spectra of individual components of the system were calculated. Finally, the integrated spectral enhancement factors of the photons absorbed and transmitted by the electrode were estimated using the different geometrical parameters of the electrode. The results suggested that the most effective absorber of light should include zinc oxide nanowires (NWs), with smaller diameters and cylindrical shapes of single gold NPs, as well as in a pattern, while the highest transmittance is obtained for greater diameter of NWs and conical shapes of gold NPs in a pattern. Based on these results, the absorption current density (derived from the generation and collection of light-generated charge carriers) was calculated for the ZnO-CdTe core-shell NWs nanostructured with gold NPs arranged into a pattern. The results suggest that the most efficient electrode contains ZnO NWs with gold NPs in a conical shaped pattern. Our results confirm the importance of computational simulation in the design of the photonic and photovoltaic devices, making it possible to predict the most efficient systems. These results could be useful to further optimize photonic or photovoltaic devices based on plasmonic NPs and semiconductor nanostructures.

The Packing Coefficient of Liquid 2-Phenylnaphthalene Molecules at 396 K

A method of measuring the angular intensity distribution of monochromatic MoK f radiation, u = 0.71069 Å scattered by a thin layer of liquid 2-phenylnaphthalene C 10 H 7 -C 6 H 5 is proposed and results of such an experiment are presented. Fourier analysis of this distribution by the procedure of Warren-Krutter-Morningstar yielded electron-density radial-distribution function (EDRDF). The curve of radiation intensity was analysed by the pair functions method. The determined mean, mutual distances between molecules of liquid studied are: [rbar] 1 = 5.30 Å, [rbar] 2 = 7.43 Å, [rbar] 3 = 12.35 Å. X-ray structural analysis was applied to determine the packing coefficient of 2-phenylnaphthalene molecules at 396 K. From the known volume of the first coordination sphere as well as the specific volume of the molecule V 0 and taking into regard the structural model of intermolecular interactions, the most probable value of the packing coefficient of the molecules was found to be [kbar] = 0.64. This value falls in the range of [kbar] values permissible for liquid phase. The results concern a wide class of molecular liquids, in particular polar compounds being naphthalene derivatives.

X-ray Scattering in Liquid Pentane

Abstract X-ray diffraction investigation of liquid n-pentane CH3—(CH2)3—CH3 was performed at 293 K. An angular distribution of X-ray scattered intensity was measured by applying MoK α (γ = 0.71069 Å) radiation. The electron density radial distribution function was numerically found using Fourier analysis. The mean distances between the neighbouring atoms were found. A simple model of short-range arrangement of the molecules was proposed.

Molecular ordering in some liquid aromatic hydrocarbons

This study presents a comparison of the structures and molecular correlations for the linear aromatic hydrocarbons: benzene, naphthalene, and anthracene in the liquid phase, performed for the first time by the method of X-ray diffraction. Also for the first time the X-ray diffraction results obtained for anthracene at 513 K have been reported. Monochromatic radiation CuKα was used to determine the scattered radiation intensity between S min = 4π sin Θmin/λ = 0.417 Å−1 and S max = 4π sin Θmax/λ = 7.06 Å−1. The mean angular distributions of X-ray scattered intensity were measured and the differential radial distribution functions of electron density (DRDFs) were calculated. The mean distances between the neighbouring molecules and the mean coordination numbers were found. The most probable models of local ordering of these molecules were suggested. Correlations have been found between the number of benzene rings in the molecules studied and their physical properties.

Model of short-range order in liquid bicyclohexyl from x-ray diffraction studies

Abstract The structure of liquid bicyclohexyl, C 6 H 11 - C 6 H 11 at 293 K was investigated using the X-ray diffraction method. Monochromatic radiation CuK α enabled one to determine the scattered radiation intensity between S 0 = 4π sin ϑ 0 /λ = 0.417 A −1 and S max = 7.06 A −1 . The angular distribution of X-ray radiation scattered was measured, and electron-density radial-distribution function (EDRDF) was numerically found using Fourier analysis. A good agreement between the theoretical and experimental functions was obtained on assuming the statistically most probable model of this molecule. The structural data obtainable by X-ray analysis for liquid bicyclohexyl were discussed. The mean distances between the neighbouring molecules were found. The maxima in the EDRDF were at : r 1 = 4.68 , r 2 = 5.57 , r 3 = 6.62 , r 4 = 8.05 A . Computer techniques were used to minimize the effects of experimental errors, uncertainties in the scattering factors, and termination errors. X-ray structural analysis was applied to determine the packing coefficient of bicyclohexyl molecules. A simple model of short-range arrangement of the molecules in liquid bicyclohexyl was proposed.

X−ray analysis of intermolecular interactions in solution of ortho−nitroanisole C7H7NO3 in 1,4−dimethylbenzene

Structural analysis of a 10% solution of ortho−nitroanisole C 7 H 7 NO 3 in 1,4−dimethylbenzene by X-ray monochromatic radiation scattering method has been made at room temperature for the scattering angle range Θ varying from 3° to 60°. Diffraction patterns of the solution were obtained on an X-ray diffractometer with an X-ray lamp with a molybdenum anode. The first lower maximum corresponds to the intermolecular distance of R 1 = 7.51 Å, and the higher one to the intermolecular distance of R 2 = 5.69 Å. The angular distribution of the intensity of X-rays scattered by 10% solution of o−nitroanisole in 1,4−dimethylbenzene is compared to that for liquid o−nitroanisole. The mean least distance obtained for the solution studied is Å. This value is almost the same as the mean distances calculated for two molecules in pure o−nitroanisole in the antiparallel arrangement between the oxygen atoms and the nitrogen atoms of the functional groups (O–CH3)1 … (O–CH3)1 and (NO2)1 … (NO2)1, equal to 7.57 Å. The results have shown that in the liquid ortho−nitroanisole, similarly as in 1,4−dimethylbenzene, the molecules are arranged with their benzene rings in parallel. The results concern a wide class of molecular liquids, in particular, polar compounds being benzene nitroderivatives.

Vibrations in atoms in liquid 1,4-dimethylbenzene

The structure of 1,4-dimethylbenzene C6H4(CH3)2 at 293 K was investigated using the X-ray diffraction method. The observable range of scattering angles was 6 ≤ 2Θ ≤ 120°. Monochromatic radiation MoKα enabled determination of the scattered radiation intensity between S min = 0.430 Å−1 and S max = 14.311 Å−1. Mean amplitudes of vibrations as a function of CC internuclear distances in 1,4-dimethylbenzene molecule were calculated. Analysis of intramolecular interactions between pairs of atoms has been made, taking into account the values of the temperature factors . Experimental distribution of scattered X-radiation intensity i(S) was compared with theoretical results predicted for a proposed model of 1,4-dimethylbenzene molecule. The best fitting theoretical curve i m (S) for the function i(S) was obtained. Also for the first time, the method of reduction proposed by Mozzi–Warren with modifications introduced by the author has been applied to verify the assumed model of the molecule studied and to separate the intra- from inter-molecular interactions. The mean distances between the neighbouring molecules and the packing coefficient of liquid 1,4-dimethylbenzene were found.

The use of the cohen–turnbull model for calculation of the self-diffusion coefficients of liquid dichloroalkanes

The paper presents the self-diffusion coefficients calculated for liquid dichloroalkanes C6H12Cl2, C8H16Cl2, C10H22Cl2 and C12H24Cl2, with the use of the Cohen and Turnbull model. Determination of self-diffusion coefficients permits a separate analysis of intra- and intermolecular motions and provides information on geometrical and dynamical properties of molecules. The self-diffusion coefficients of selected dichloroalkanes have been determined by X-ray diffraction and compared with the corresponding NMR results. The suitability of the Cohen–Turnbull model of the translating motion for prediction of self-diffusion coefficients for molecules whose shape significantly differs from the spherical symmetry is analysed. Angular distributions of X-ray scattered intensity were measured, and differential radial distribution functions of electron density (DRDFs) were calculated. The mean coordination numbers were obtained from the area delimited by the minima of the DRDFs, and their dependence on the length of the methylene chain is also presented subsequently. On the basis of the DRDFs the average free volume of the molecules and total free volume of the liquids were calculated. The activation volume of the diffusion was found to make about 0.6 of the van der Waals volume of the molecule. As expected the diffusion coefficients decrease with increasing molecular weight. The equation relating the self-diffusion coefficient with the volume of the coordination spheres in the liquid has been derived.