Oleg M. Samatov

Laser Target Evaporation Fe 2 O 3 Nanoparticles for Water-Based Ferrofluids for Biomedical Applications

Maghemite spherical magnetic nanoparticles (MNPs) were prepared by laser target evaporation. X-ray diffraction, transmission electron microscopy, specific surface area, and dynamic light scattering studies were performed. For water-based suspensions prepared on the basis of obtained MNPs, the zeta potential was measured. Magnetic and microwave measurements were performed both for MNPs and ferrofluids. To estimate the inductive magnetic heating of electrostatically self-stabilized or electrostatically stabilized by adsorbed citrate ions ferrofluids, magneto-inductive heating experiments were performed that showed heating efficiency. For the study of cytotoxicity and maghemite MNPs accumulation process, two non-pathogenic Exophiala nigrum (black) and its mutant strain (red) yeasts were studied. In both cases, no significant alterations of cell morphology were observed.

Production of Nanopowders with the Help of Fiber Laser

Development of an efficient technology to produce nanopowders for nanostructured materials with improved mechanical, novel electromagnetic and optical properties is still of current importance. Nanoparticles can be made by means of laser-assisted material evaporation and subsequent vapor condensation. The method provides high-purity weakly agglomerated nanopowders with narrow grain size distribution, and can be applied to various materials. However, up to these days this technique has not found wide recognition because of a low output rate and high energy consumption. This report deals with the production technology and characteristics of nanopowders produced with the help of Yb-doped fiber laser. Data for the nanopowders characteristics, as well as output rate and energy consumption are discussed in this paper. The evaporation of materials with the help of the fiber laser was proved to be an efficient method for commercial production of the fine nanopowders.

Synthesis of Strontium Hexaferrite Nanopowder by the Laser Evaporation Method

Nanopowder of a magnetically hard material—strontium hexaferrite—has been synthesized using laser evaporation followed by annealing. The phase composition, magnetic properties, and dispersion characteristics of the nanopowder have been investigated. As was shown by electron microscopy studies, upon laser evaporation the powder particles have a regular spherical shape and the size of the main fraction is in the range of 5–50 nm. From the data of X-ray phase analysis, the synthesized powder contains a large amount of the amorphous phase, whereas magnetite (iron oxide) is the main crystalline component. From the data of magnetic measurements, the nanopowder has low saturation magnetization and there are no magnetically hard properties. The effect of thermal treatment on the nanopowder phase composition, dispersion, and magnetic properties has been studied. It has been demonstrated that heating up to 820°C results in the crystallization of the amorphous component of the nanopowder, which increases the ferrite phase content up to 90 wt %, and the material manifests magnetically hard. In this case the degree of dispersion decreases, but the powder remains nanosized.

Biocompatible Ferrofluids With Iron Oxide Nanoparticles Fabricated by Laser Target Evaporation

Iron oxide magnetic nanoparticles were obtained by a highly productive laser target evaporation technique while varying type and pressure of the working gas and laser pulse duration and average output power. Water-based suspensions stabilized with sodium citrate were prepared. Synthesis in air, 100 μs laser pulse duration, and 200 W average power resulted in disaggregated superparamagnetic nanoparticles with an average diameter of 9.9 nm.

Characteristics of ZrO2 nanopowders produced by electrical explosion of wires

A device and an experiment for obtaining zirconium dioxide nanopowders using the electrical explosion of a wire (EEW) with aerodynamical separation are described. The physicochemical and technological properties of powders depending on the conditions under which they are obtained are studied. It is shown that, like for other metals with high oxidation heat, there is an additional dispersion of powders due to combustion. The results are discussed from the point of view of current concepts of electrical explosion and the combustion of metal powders. The optimum technological conditions according to the criterion of the maximum nanofraction yield were found. It is shown that this method allows us to obtain weakly aggregated ZrO2 nanopowders with a spherical particle shape (the specific surface reaching 70 m2/g (average particle size <20 nm)) and a nanofraction yield of up to 28% of the theoretical weight of oxide.

Photocatalytic activity of titanium dioxide nanoparticles produced by methods of high-energy physical dispersion

Photocatalytic activity of titanium dioxide nanoparticle samples under study is almost uncorrelated with their phase composition and, in particular, with the content of the anatase phase. The photocatalytic activity depends on the annealing temperature of the nanoparticles. The photocatalytic activity is positively affected by an ultrasonic radiation of the nanoparticles. The highest photocatalytic activity, comparable with that of the AEROXIDE P25 reference nanopowders, is observed for nanoparticles produced by a method of electrical explosion of wires.