D. V. Nazarov

Formation of Micro- and Nanostructures on the Nanotitanium Surface by Chemical Etching and Deposition of Titania Films by Atomic Layer Deposition (ALD)

In this study, an integrated approach was used for the preparation of a nanotitanium-based bioactive material. The integrated approach included three methods: severe plastic deformation (SPD), chemical etching and atomic layer deposition (ALD). For the first time, it was experimentally shown that the nature of the etching medium (acidic or basic Piranha solutions) and the etching time have a significant qualitative impact on the nanotitanium surface structure both at the nano- and microscale. The etched samples were coated with crystalline biocompatible TiO2 films with a thickness of 20 nm by Atomic Layer Deposition (ALD). Comparative study of the adhesive and spreading properties of human osteoblasts MG-63 has demonstrated that presence of nano- and microscale structures and crystalline titanium oxide on the surface of nanotitanium improve bioactive properties of the material.

Atomic layer deposition of tin oxide using tetraethyltin to produce high-capacity Li-ion batteries

The authors deposited thin films of tin oxide on substrates of silicon and stainless steel by using atomic layer deposition (ALD) with tetraethyltin precursors. In this process, the authors used various coreactants such as water, oxygen, remote oxygen plasma, hydrogen peroxide, and ozone. The growth rates of films were studied as functions of the deposition temperature, the pulse times of the precursor and coreactant, and the number of ALD cycles, and the optimal growth conditions were determined. The film growth rates were found to be 0.025, 0.045, and 0.07 nm per cycle within the optimal growth conditions and ALD temperature windows for H2O2, O3, and O2 plasma, respectively. Using H2O or O2 did not prompt film growth. The films deposited using O3 and H2O2 had good continuity and low roughness, while the morphology of a coating prepared using oxygen plasma depended greatly on the deposition temperature. The films produced at temperatures below 300 °C were amorphous, irrespective of the coreactant used. X...

Cyclic stability of the anode material based on tin(IV) oxide for thin-film current sources

The cyclic stability of thin films (~40 nm) of an anode material based on tin dioxide at charging voltages of 2.5, 1.5, and 0.8 V was studied. The electrodes were prepared on a Picosun R-150 installation using tetraethyltin and remote inductively coupled oxygen plasma.

Modification of the Surface Topography and Composition of Ultrafine and Coarse Grained Titanium by Chemical Etching

In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed.

Low-temperature deposition of tin(IV) oxide films for thin-film power sources

Thin films of tin(IV) oxide were deposited in a Picosun R-150 installation from tetraethyltin using remote inductively coupled plasma at temperatures lower than 200°C with the aim of developing a material for thin-film current sources. The thickness and morphology of the films were studied by spectral ellipsometry and scanning electron microscopy. Both the thickness and roughness of the films considerably decrease with an increase in the synthesis temperature in the interval 100–180°C. The films are X-ray amorphous. As shown by X-ray photoelectron spectroscopy, tin in the films is in oxidation state +4.

Peculiarities of phase transitions in nanosized vanadium dioxide: Magnetic characteristics

Samples of pure and chromium- or iron-doped nanosized vanadium dioxide of different morphologies were fabricated by the method of atomic layer deposition (ALD) on the surface of substrates of different structures: amorphous silica and single-crystal silicon. The samples were characterized using photometry and magnetochemical analysis. The occurrence of the semiconductor-metal phase transition (SMPT) was demonstrated on the basis of temperature dependencies, and it was shown that the transition characteristics depended on the substrate type and the nature and amount of the doping element. The SMPT temperature decreases from 340 K (the value characterizing the bulk material) to 100–180 K, depending on the sample composition and structure.

Specific features of etching of ultrafine- and coarse-grained titanium in base and acid solutions of hydrogen peroxide

The character and kinetics of chemical etching of nanostructured titanium in base (NH4OH/H2O2) and acid (H2SO4/H2O2) solutions of hydrogen peroxide (Piranha) were studied. A study of the etching kinetics showed that the etching rate of the nanostructured titanium is not constant and tends to decrease, but in the case of the sulfuric acid solution the decrease is smoother owing to the growth of the oxide layer. The etching rate for ultrafine-grained titanium is higher than for the coarse-grained sample. The applied significance of the study is associated with the fact that Piranha solutions show promising for cleaning, hydrophilizing, and making rough the titanium surface for use in medical implants.

Atomic layer deposition of tin oxide nanofilms using tetraethyltin

Due to variety of applications of tin oxide thin films such as solid state gas sensors, solar cells, transparent conductive oxide coatings, catalysts, and anodes for Li-ion batteries, it is desirable to develop convenient and high effective technique of atomic layer deposition for this material. In this paper we consider in details the prospects of using tetraethyltin to produce thin films of tin dioxide by atomic layer deposition. Water, hydrogen peroxide, oxygen, ozone and oxygen plasma were used as co-reactants for SnOx deposition. It was found that the type of co-reactant has a huge impact on the growth rate, composition and morphology of the films. Features of synthesis and prospects for use the films in lithium-ion batteries are considered.

Synthesis and electrophysical characteristics of VO2-based nanostructures with a complicated architecture on a silicon surface

Nanofilms of complicated architecture based on VO2 and containing chromium were synthesized by the molecular layering method. The study of electrophysical characteristics of vanadium dioxide nanocrystallites and of VO2-containing chromium has shown that semiconductor-metal phase transitions appear in the ranges of 130–160 and 100–110 K, respectively. The introduction of a transition-element ion in the nanostructures based on VO2 affects the phase transition characteristics.