Interest in nanostructures is determined by their wide range of potential applications in various fields of electronics, optics, magnetism, electrochemistry, biology, and medicine. A commonly used method involves incorporating nanoscale objects into “parent” matrices with micro- or nanopores, which leads to the creation of composite materials. Nanostructured composite materials synthesized in this way often exhibit a number of fundamentally new properties compared to homogeneous bulk materials of the same chemical composition, which are the basis of porous matrices or filling materials for such matrices.
The technology we have developed involves:
1) the actual manufacture of nanoporous matrices from Al2O3 using an electrochemical synthesis method;
2) the process of preparing saturated aqueous solutions (KDP, ADP, KB5, Ba(NO3)2, HIO3, TGS, and others) for the growth of nano- or microcrystals in porous matrices of Al2O3, SiO2, and Si from recrystallized raw materials at appropriate growth temperatures;
3) filling porous matrices of Al2O3, SiO2, and Si (pore diameter 5÷90 nm and 1÷10 μm, respectively) with nano- or microcrystals from saturated aqueous solutions using elevated temperatures and ultrasonic technologies;
4) filling these same nanoporous matrices with nanocrystals from saturated aqueous solutions using the method of pressure drops between matrix surfaces;
5) formation of nanocrystalline structures in the form of nanorods/nanotubes using appropriate temperature and time regimes for filling nanoporous Al2O3 matrices;
6) formation of nanocrystalline structures based on the known high-temperature lithium niobate (LiNbO3) crystal, due to the presence of water-soluble compounds, which makes it possible to obtain a saturated aqueous solution of LiNbO3, which during subsequent synthesis at a temperature of 950°C forms a crystalline compound in the pores of Si and SiO2 matrices.
The proposed technology makes it possible to significantly increase the efficiency of introducing substances with active physical properties into porous matrices, significantly expand the functional capabilities of the introduced components, and significantly increase the practical significance of such structures. The interdisciplinary field of nanoengineering, combined with the relatively new field of nanotechnology, holds the key to many new and innovative developments in the future.
Currently, nanostructured composite materials based on porous oxides are the subject of intensive study, among which aluminum oxide (Al2O3) stands out for its relative ease of production in sulfuric, oxalic, and phosphoric acid electrolytes. The self-organized array of pores formed during the etching process has a uniform density of ~109-1010 cm-2 with an average pore size. Organized nanostructures can also be grown in porous silicon obtained by electrochemical etching of Si wafers. When deposited in the pores of a selected matrix, the corresponding material gives such a composite new physical properties. The deposition of quantum dots allows the formation of structures with unique optical and luminescent properties, suitable for the development of optical methods and the creation of new optoelectronic elements, etc.