Vorobyova Svetlana

Research Institute for Physical Chemical Problems · Chemistry

The local atomic order, magnetic properties, hyperthermia efficiency, drug loading capacity and in-vitro cyto-toxicity are investigated for the core-shell (Fe 25 Co 75) x (SiO 2) 100-x (70 ≤ x ≤ 100, wt.%) nanoparticles (NPs) sintered by the metals co-precipitation followed with SiO 2 TEOS deposition. Electron microscopy reveal the formation of nea...

Bimetallic nanocomposite particles of FeCo and FeCo@SiO2 were prepared by chemical reduction of Co(II) and Fe(II) salts in solutions. The particle size, morphology and composition of the nanocomposites were studied by transmission and scanning electron microscopy, powder XRD, X-ray fluorescence and complex thermal analysis. It was established that...

FeO ⋅ Fe2O3 ⋅ nH2O, Fe2.95Gd0.05O4 and Fe2.9Gd0.1O4 powders were obtained by chemical precipitation from aqueous solutions. The phase composition and local environment of iron ions in gadolinium-doped iron oxide nanoparticles were studied by X-ray diffraction analysis and nuclear gamma resonance (NGR) spectroscopy. Interpretation of radiographs and...

The novel iron-oxide nanoparticles (NPs) stabilized with triethanolammonium oleate were produced. The specimens were divided into two groups: the top NPs (extracted from the supernatant) and the bottom NPs (nanoparticles sedimented at the bottom of the flask during centrifugation), respectively. The XRD and Mössbauer studies revealed a presence of...

The paper reports on the charge transport in the sandwich-like graphene / Co nanoparticles / graphene structure (G/CoNPs/G). It is fabricated by combining the electrochemical deposition of Co nanoparticles onto a single layer CVD graphene and their capping with another graphene layer. The isolated semi-spherical, surface oxidized Co NPs of 250 nm i...

In this work, we investigate structure and magnetic properties of nanoparticles (NPs) containing Fe_{x}Co_{1-x} (25<x<75, wt.%) core inside mesoporous SiO_{2} shell sintered with different molar ratios of FeCo and SiO_{2} by two-stage procedure including FeCo coprecipitation and SiO_{2} TEOS hydrolysis.

Graphene applications in electronics require experimental study of the formation of high-quality Ohmic contacts and deeper understanding of electron transport mechanisms at metal/grapheme contacts. We have studied carrier transport in twisted CVD graphene decorated with electrodeposited Co particles forming Ohmic contacts with graphene layers. We h...

Application of magnetic metal/graphene hybrid structures in magnetosensorics requires the formation of high-quality low-ohmic (barrier-free) contacts and understanding of mechanisms of electric charge transfer near and through the metal/graphene contact area. In present paper we fabricate samples of twisted graphene electrochemically decorated with...

Electrochemical deposition of cobalt nanoparticles was used to modify carrier transport properties of single-layered CVD graphene at the SiO2-on-Si substrate. The structure of graphene with cobalt nanoparticles was analyzed by Raman spectroscopy and scanning electron microscopy. The effect of the deposited cobalt nanoparticles on the sheet resistan...

Synthesis of nanoparticles of metals and their compounds with given morphology and dispersity for use in medicine, pharmacology, microelectronics, as well as subsequent research of their properties, is one of the current problems in the field of preparative inorganic chemistry. Interphase synthesis and redox-transmetalation reduction are as promisi...

Composite nanoparticles (NPs) of FeCo-Ag and FeCo-Au fabricated by the redox-transmetalation technique are characterized by transmission electron microscopy (TEM), X-ray diffractometry (XRD), Mössbauer spectroscopy and magnetometry. TEM images prove the formation of agglomerated quasi-spherical NPs with mean value of diameter about 28 nm. As indica...

The paper reports on the first successful fabrication of Co-graphene composites by electrochemical deposition of Co nanoparticles (NPs) on the sheets of twisted graphene. Characterization of the surface morphology and element mapping of twisted graphene decorated with Co NPs by transmission and scanning electron microscopy in combination with the e...

A facile and reliable synthesis route to Cu-graphene nanoplatelets (GNP) hybrid films has been developed. Cu nanoparticles of 13.7 ± 3.4 nm mean size were attached to few-layer graphene sheets. The obtained composite has good film forming properties and resistance of 380 Ω as compared to pure GNP, forming unstable and weakly conductive films. Intro...

The latest our results on triple polymer composites based on graphene nanoplatelets (GNP) covered by copper nanoparticles, iron oxide nanoparticles, and CdSe two-dimensional and spherical nanoparticles are presented and analyzed. It was found that GNP covered by copper nanoparticles results in higher conductivity and film stability increase in PEDO...

The absorption spectra in the visible region and current-voltage characteristics in a wide range of electric fields have been investigated at the macroscopic level (planar structures) and at the microscopic level (using a conductive atomic force microscope) in films based on the electroactive polymer PEDOT: PSS and gold/silver nanoparticles (PEDOT:...

A synthesis method to prepare Fe-Pd composite nanoparticles is presented. Structure and phase composition, morphology and magnetic properties of the obtained powders were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), ferromagnetic resonance (FMR) and Mössbauer spectroscopies.

A simple technique for preparation of stable gold colloidal solutions by interaction of tetrachloroauric acid and sodium borohydride in the presence of sodium folate was developed. The morphology of gold nanoparticles and their optical properties were characterized by TEM and UV-visible spectroscopy.

A simple room temperature technique of Fe3O4/Au nanocrystals preparation in two-phase system was reported. The organic phase contains the mixture of the octane-based magnetic fluid and chloroauric acid complex with quaternary ammonium compound. AuCl4− was transferred from aqueous solution to octane using N-(2-(didecylamino) ethyl)-N,N-tridecyldecan...

CdS and Fe3O4/CdS core–shell nanoparticles were synthesized by a simple interphase method. The obtained nanoparticles were characterized by TEM, XRD and spectroscopy techniques (fluorescence and UV–vis absorption). The effects of reagent concentration on the properties of obtained nanoparticles were investigated. It was shown that the UV–vis spectr...

Two types of composite films on the basis of n-conjugated polymers, poly-(N-epoxypropyl)carbazole (PEPC) and poly-(N-vinyl)carbazole (PVC), and metal nanoparticles have been fabricated. The sizes of nanoparticles depend on type of the polymer matrix. Complex testing of the obtained materials has shown that conductivity and optical effects are more...

ColloIDal dispersions and thin films containing poly-N-(epoxypropyl)carbazole (PEPK) and Ag—Au nanoparticles (2–3 nm in diameter) were prepared and investigated by TEM, optical and IR spectro-scopy, and electrophysical tools. The introduction of nanoparticles results in cooperative phenomena between the polymer and the Ag—Au particles; as a consequ...

The facilities of one-step preparation method of nickel nanoparticles by the interphase reduction of nickel oleate using sodium borohydride at room temperature without soluble polymer as a protective agent were studied. Nickel obtained by such technique was concentrated in aqueous phase as a black dispersion. The composition and morphology of the c...

Cadmium sulfide stable colloidal dispersions in hexane, toluene and toluene solution of polystyrene or polyepoxypropylcarbazole have been obtained by the interphase interaction of cadmium oleate and sodium or hydrogen sulfide dissolved in organic solvent and water, respectively. The effect of the precipitant nature and starting molar ratio Cd2+/S2−...

The facilities of one-stage synthesis of magnetic cobalt nanoparticles by the interphase reduction of cobalt oleate (hexane or toluene solution) and sodium borohydride (aqueous or ethanol solution) at room temperature without a soluble polymer as a protective agent have been studied. The resultant cobalt nanoparticles have been concentrated either...

A study has been made on the regularities determining the electrophysical properties of magnetic fluids based on decane, turbine oil and kerosene as functions of the electric field frequency, concentration of the dispersed phase and the temperature. The optimum frequencies of the electric field, concentration of the dispersed phase and temperatures...

A short review on achievements of conducting and luminescent nanocomposites as well as spectroscopic and electrophysical properties of thin polymer films containing metal and semiconductor nanoparticles and the data of studies of thin films and ITO/nanocomposite/Al or metal/nanocomposite/metal structures mainly based on poly‐N‐epoxypropylcarbazole...

The colloidal dispersions and thin films containing poly-N-(epoxypropyl)-carbazole (PEPC) and Ag-Au nanoparticles were prepared and investigated by TEM and UV-vis spectroscopy. The interaction between poly-N-(epoxypropyl)-carbazole and Ag-Au nanoparticles were studied by IR-spectroscopy. It was shown that interaction of nanoparticles and polymer fu...

ZnS toluene colloidal dispersions have been synthesized by an interphase interaction of toluene zinc oleate solution and aqueous solution of hydrogen sulfide. XRD analysis shows the crystal cubic structure of ZnS particles. According to TEM their size varies between 2 and 10 nm. The UV-vis absorption spectra indicate the prepared nanoparticles to h...

Highly luminescent nanocomposite thin film consisting of polyfluorene with imbedded CdS nanoparticles are developed. Strong cathodoluminescence has been observed under irradiation by a pulsed high energy electron beam giving a new conception to create a printable screen for field emission display. The spectrum of cathodoluminescence contains emissi...

Absorption and luminescence spectra as well as the temperature dependences of electrical conductivity of polyepoxypropylcarbazole (PEPC) with Ag nanoparticles are studied. Polyepoxypropylcarbazole results in an additional stabilization of Ag nanoparticles. They cause essential PEPC photoluminescence quenching. An additional maximum in the luminesce...

The comparative preparation of magnetite magnetic liquids by conventional and novel techniques is described and some characteristics of the obtained liquids are discussed. By contrast to conventional technique, according to novel technique the oleic acid was prepared by the interaction of sodium oleate and hydrochloric acid coincidentally with the...

Metal nanoparticles in an active part of an electroluminescent cell possess to increase the average electric field inside the cell and, as a consequence, electroluminescence brightness and efficiency, and to decrease the threshold of electroluminescence, due to improving conditions of electron tunneling as a result of potential barriers shape chang...

The preparation of zinc oxide by interphase synthesis is described. The dispersity and phase composition of the obtained sediments are analysed by the methods of scanning electron microscopy and X-ray diffraction. It is concluded that the particles shape and phase of their localization depend on the reaction conditions (temperature, reagent ratio a...

The electrophysical properties of magnetic fluids based on decane and kerosene depending on the concentration of the dispersed phase and temperature under different electric field frequencies have been studied. Different structural states of magnetic fluids under relatively low and high concentrations of the dispersed phase have been revealed. The...

The interphase preparation of gold dispersions in hexane using N,N-tridecyl(3-aza-3decyltridecan)ammonium iodide as the phase transfer agent is described. Dispersity and phase composition of the disperse phase of colloidal dispersions were analysed by chemical analysis, transmission electron microscopy (TEM), X-ray diffractometry (XRD), X-ray photo...

The fire retardant action of red phosphorus in nylon 6 was improved by co-addition of ferric/ferrous oxides. It was found that the activity of Fe oxides depends on the product grade. Polymer formulations non-ignitable in air were obtained by co-addition of Fe3O4/Fe2O3 = 3:2 with red phosphorus. Scanning electron microscopy showed that ferric oxide...

The interphase synthesis of silver dispersions in decane without using of surfactants were described. Dispersity and phase composition of the disperse phase of the colloidal dispersions were analysed by the methods of the chemical analysis, electron microscopy, X-ray and UV-vis spectroscopy. It was shown that the disperse phase of the colloidal dis...

The colloidal copper oxide (II) solution in octane was synthesized by interphase interaction between copper (II) oleate and sodium hydroxide. The resulting two-phase was stirred for 2 hours at 95 °C without disturbing octane-water interface. The brown colloidal solution of CuO in octane was obtained. The particle size distribution and the compositi...

A colloidal silver solution in the organic phase was synthesized by chemical reduction in a two-phase system (decane-water) without special stabilizers. Dispersity and phase composition of the disperse phase of the colloidal solution were analysed with the methods of chemical and X-ray analyses, electron microscopy, UV;and visible spectroscopy It i...

The dispersity of ferrophase particles and the interaction with a surfactant in magnetic liquids based on magnetite stabilized by oleic acid are investigated. It is shown that oleic acid at the surface of the ferrophase is free and/or chemically bound. When preparing and aging the magnetic liquid, oleic acid undergoes an oxidative destruction; the...