Peculiar Porous Aluminum Oxide Films Produced viaElectrochemical Anodizing in Malonic Acid Solution withArsenazo-I Additive

The influence of arsenazo-I additive on electrochemical anodizing of pure aluminum foil in malonic acid was studied. Aluminum dissolution increased with increasing arsenazo-I concentration. The addition of arsenazo-I also led to an increase in the volume expansion factor up to 2.3 due to the incorporation of organic compounds and an increased number of hydroxyl groups in the porous aluminum oxide film. At a current density of 15 mA·cm–2 and an arsenazo-I concentration 3.5 g·L–1, the carbon content in the anodic alumina of 49 at. % was achieved. An increase in the current density and concentration of arsenazo-I caused the formation of an arsenic-containing compound with the formula Na1,5Al2(OH)4,5(AsO4)3·7H2O in the porous aluminum oxide film phase. These film modifications cause a higher number of defects and, thus, increase the ionic conductivity, leading to a reduced electric field in galvanostatic anodizing tests. A self-adjusting growth mechanism, which leads to a higher degree of self-ordering in the arsenazo-free electrolyte, is not operative under the same conditions when arsenazo-I is added. Instead, a dielectric breakdown mechanism was observed, which caused the disordered porous aluminum oxide film structure.

FEATURES OF STIMULATED EMISSION OF A MEROCYANINE DYE IN THE PORES OF ANODIZED ALUMINUM

The results of the study of the spectral-luminescent properties and the generation of stimulated emission of merocyanine dye molecules in a porous aluminum oxide films are presented. The addition of silver nanoparticles to the porous aluminum oxide films leads to an increase in the absorption cross section and an increase in the quantum yield of dye fluorescence in the alumina films. However, in the alumina films with silver nanoparticles, the generation of stimulated emission of dye molecules was not detected. We also studied the effect of polymethyl methacrylate polymer deposited on the surface of the alumina films with a dye on the spectral-luminescent properties and generation of stimulated emission of this dye. An increase in the optical density in the absorption band of the dye and an increase in the fluorescence intensity in samples with a deposited polymethyl methacrylate film are observed. The generation threshold of polymethine dye is reduced by a factor of 40 in the porous aluminum oxide sample with polymethyl methacrylate.

Electrical and Optical Properties of Nanocomposites Fabricated by the Introduction of Iodine in Porous Dielectric Matrices

The electrical and optical properties of nanocomposite materials fabricated by the dispersion of iodine in porous dielectric matrices of zeolites, zeolite-like aluminum phosphates, opals, asbestos, and porous aluminum oxide are studied. It is demonstrated that the physical properties of the produced nanocomposites depend significantly on the structure of a matrix.

EVOLUTION OF THE DIELECTRIC PROPERTIES OF SODIUM NITRITE INTRODUCED INTO ALUMINUM OXIDE NANOPORES

This work presents the results of studying the evolution of the dielectric properties of nanocomposite NaNO2/Al2O3 samples with pore sizes of 100 and 70 nm. The samples were examined by dielectric spectroscopy. It is shown that in nanosized sodium nitrite embedded in porous aluminum oxide, the effect of «aging» associated with the time factor is observed. A decrease in the values of the dielectric constant is observed during long-term storage of the sample under normal conditions.