Publications by authors named "Mikhail Pashchanka"

First of all, I would like to thank Silvio Heinschke and Jörg J. Schneider (hereinafter referred to as "the Readers") for preparing their Comment [..

View Article and Find Full Text PDF

This work provides a conceptually new way of thinking about the light-absorbing mechanism in additive-free black porous anodic alumina (black PAA, or b-PAA) layers obtained via "burning" anodizing regime. The new insight into the controllable photonic effects in PAA allows the implementation of the optical blackening method based on the deliberate randomization of the initially well-ordered nanopore arrangement. The proposed black coloration mechanism rests solely on the destructive interference of light after its multiple scattering.

View Article and Find Full Text PDF

Over the past few years, researchers have made numerous breakthroughs in the field of aluminum anodizing and faced the problem of the lack of adequate theoretical models for the interpretation of some new experimental findings. For instance, spontaneously formed anodic alumina nanofibers and petal-like patterns, flower-like structures observed under AC anodizing conditions, and hierarchical pores whose diameters range from several nanometers to sub-millimeters could be explained neither by the classical field-assisted dissolution theory nor by the plastic flow model. In addition, difficulties arose in explaining the basic indicators of porous film growth, such as the nonlinear current-voltage characteristics of electrochemical cells or the evolution of hexagonal pore patterns at the early stages of anodizing experiments.

View Article and Find Full Text PDF

Herein, the one-step spontaneous formation of multiscale hierarchical honeycomb-like textures on anodized aluminium is reported for the first time. A self-organized array of unprecedentedly large sub-millimetre hemispherical pores was observed on the upper hierarchy level, while superimposed well-ordered hexagonal cells on the lower hierarchy level maintained their classically known nanoscale self-ordering periodicity (50-60 nm). The larger macroscopic cells (0.

View Article and Find Full Text PDF

A comparative study of self-ordering behaviour of anodic alumina films fabricated in a series of diluted (down to 0.05 M) oxalic acid electrolytes allowed developing a relationship between the supporting electrolyte concentration and self-ordering voltages for the formation of porous oxide materials. Besides its practical importance, this work elucidates some fundamental principles of porous alumina formation, e.

View Article and Find Full Text PDF

Metallic Cr, Al, and Pt/Pd alloy have been deposited by magnetron sputtering or thermal evaporation (resistance heating or electron beam heating) onto nanoporous anodic alumina and have allowed to facilitate a cost-effective technique for manufacturing of pigment-free colored coatings on aluminum. Bright and saturated colors were achieved using the interference effect, and tuned by variation of the uniform oxide film thickness. Morphology and properties of these coatings were investigated by scanning electron microscopy (SEM) and reflectance measurements (UV/Vis/NIR spectrometry).

View Article and Find Full Text PDF

Polycrystalline CuInSe2 (CISe) nanorods are promising for the fabrication of highly efficient active layers in solar cells. In this work we report on a nanocasting approach, which uses track-etched polycarbonate films as hard templates for obtaining three-dimensionally (3D) arranged CISe nanorod arrays. Copper and indium ketoacidoximato complexes and selenourea were employed as molecular precursors.

View Article and Find Full Text PDF

The lack of a reliable method for theoretical prediction of nanoporous anodic alumina films obtained from non-familiar electrolytes prompted the search of a viable solution to this problem. The theory explaining the self-assembly mechanism was described in our preceding work. Here, the results of an extensive validation test are presented.

View Article and Find Full Text PDF

A novel molecular approach to the synthesis of polycrystalline Cu-doped ZnO rod-like nanostructures with variable concentrations of introduced copper ions in ZnO host matrix is presented. Spectroscopic (PLS, variable temperature XRD, XPS, ELNES, HERFD) and microscopic (HRTEM) analysis methods reveal the +II oxidation state of the lattice incorporated Cu ions. Photoluminescence spectra show a systematic narrowing (tuning) of the band gap depending on the amount of Cu(II) doping.

View Article and Find Full Text PDF