Genoveva Atanasova

Genoveva Atanasova
Bulgarian Academy of Sciences | BAS · Institute of General and Inorganic Chemistry

About

73
Publications
7,571
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934
Citations
Citations since 2016
43 Research Items
687 Citations
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120

Publications

Publications (73)
Article
Full-text available
The work presents the main characteristics of the process of ablating silicon nitride ceramics by nanosecond laser pulses. Two types of ceramics are considered—tape cast and gas pressure sintered. Laser processing was performed by a Q-switched Nd:YAG laser system at four wavelengths—266 nm, 355 nm, 532 nm, and 1064 nm. The ablation depth dependence...
Article
Full-text available
This study is focused on the design control of Cu–Zr–Ti oxide composites by the variation of the Zr/Ti ratio and the copper deposition procedure used. For the first time, these ternary composites were obtained by a combination of template-assisted hydrothermal techniques for the preparation of mesoporous ZrO2–TiO2 mixed oxides with diverse composit...
Article
We report on the preparation of highly porous metal-oxide nano-structures using pulsed laser deposition in air at atmospheric pressure. The depositions were carried out by ablating two types of targets, namely, pure ZnO and composite ZnO/noble metal targets. The attention was concentrated on the morphology and on the optical and sensing properties...
Article
This work presents results on nanosecond laser-induced surface structuring of AlN ceramic. The process under investigation is performed using the fundamental wavelength of Nd:YAG laser system. It is shown that the change of the ambient air pressure from atmospheric one to 10⁻⁴ Torr, leads to modification of the surface morphology – from ripples str...
Article
In this work, we show that nanosecond laser processing of aluminium nitride (AlN) ceramic by a Nd:YAG laser operated at the fundamental wavelength (1064 nm) leads to the formation of a conductive layer decorated by a ripples structure. The characteristic orientation of these structures is perpendicular to the incident laser polarization. The period...
Article
Full-text available
The common approach to modify the thermoelectric activity of oxides is based on the concept of selective metal substitution. Herein, we demonstrate an alternative approach based on the formation of multiphase composites, at which the individual components have distinctions in the electric and thermal conductivities. The proof-of-concept includes th...
Article
The authors have demonstrated that incorporation of poly(ethyleneimine) (PEI) coated polyaniline-silica (PANI-SiO2) particles into the zinc coating matrix improves the corrosion resistance of low carbon steel in a 5% NaCl solution compared to the bare zinc coating. The zinc and hybrid coatings were electrodeposited on a steel cathode surface at pH...
Article
The paper presents experimental results on fabricating composite nanostructures consisting of magnetic and non-magnetic metal oxide nanoparticles. The samples were produced by a single-step process of pulsed laser deposition carried out in air at atmospheric pressure in the presence of a magnetic field. Part of the depositions was performed by abla...
Article
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A series of mesoporous cerium-iron binary oxides was prepared by a hydrothermal technique using CTAB as a template. The influence of the Fe/Ce ratio and the variations in the preparation techniques such as the type of solvent and the precipitation agent, the approach of the template release, and the temperature of calcination on the phase compositi...
Article
In this work, we demonstrate a novel way of fabricating oriented composite nanowires consisting of arranged nanoparticles. The structures are produced by an advanced pulsed laser deposition technology involving the simultaneous ablation of two metal targets, Fe and Ag. The depositions are carried out in air at atmospheric pressure in the presence o...
Article
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Highly porous pure and noble metal (Ag, PdAg and Pd) doped ZnO nanostructures were fabricated by pulsed laser deposition (PLD) in air at atmospheric pressure (in open air). This technology leads to the formation of nanostructures composed of nanoparticles or nanoaggregates. The as-deposited nanostructures possess a large surface-to-volume ratio, wh...
Article
Hydrothermally obtained mesoporous ceria-titania mixed oxides with different composition are modified with copper using incipient wetness impregnation and “chemisorption-hydrolysis” techniques. Their catalytic properties in methanol decomposition as a source of hydrogen and total oxidation of ethyl acetate as representative volatile organic polluta...
Article
Full-text available
A nanocomposite CrAlSiN–AlSiN coating with periodically modulated composition was developed and investigated regarding the effect of the composition and structure on the mechanical properties. The modulation was performed by variation of the pressure, cathode current and bias voltage during deposition. The structure and composition of the coating w...
Article
A novel and effective approach is suggested for fabrication of composite Ag/ZnO nanostructures for surface-enhanced Raman scattering (SERS) by combining laser and ion implantation techniques. The study explores the relation between the nanoscopic features of the prepared Ag/ZnO nanocomposites and their effectiveness as SERS active substrates. The Z...
Article
In this work, we present fabrication and studies of pure and Pd-decorated ZnO nanostructures on Ag-coated substrates in view of gas-sensing application. The sensor elements consist of a dense structure of ZnO nanobelts. The chemical composition of the surface and gas-sensing properties of pure and Pd-doped nanostructures were studied and compared....
Article
Highly porous pure and silver-doped ZnO 3D nanostructures were formed by PLD in open air with a view of sensor applications. Under irradiation with UV light, the response of pure ZnO and of Ag-ZnO sensor elements was studied to NH3, CO, ethanol, and acetone. The presence of Ag nanoparticles in the ZnO nanostructure improved considerably the sensor...
Article
The process of laser radiation-induced formation and decomposition of Ag nanoparticles in glass is studied. Borosilicate glass samples are fabricated by melt quenching method. Silver nitrate is added in the fabrication stage in amount to form final glass samples with compositions of 1, 1.5, 5, and 10 wt% Ag. The fabricated samples are irradiated by...
Article
This work represents results on the response of noble metal-doped borosilicate glass to laser radiation with femto- and nanosecond pulse duration. The material under study is obtained by conventional melt quenching method as samples with noble metal concentration varied up to 10 wt% are fabricated. Optical and morphology changes of the glass sample...
Article
The present study focuses on the synthesis of noble metal (Au, Ag) nanoparticles and their incorporation and manipulation in thin film oxide matrix. The structural and functional properties of the nanoparticles embedded in a host matrix of fused SiO2 films are covered by this research. The effect of post-deposition laser or thermal annealing proced...
Article
The aim of the present investigation was to demonstrate a preparation method for obtaining an electrodeposited composite zinc coating with incorporated carbon nanotubes (CNT). The composite coatings were additionally treated in a newly developed conversion solution based on a Cr(III)-containing compound. The surface morphology of the Cr(III) and no...
Article
In this work, we report fabrication of highly porous metal-oxide nanostructures by pulsed laser deposition performed in air at atmospheric pressure. The attention was focused on the structure, morphology, and composition of ZnO, TiO2, SnO2 and MoO3 metal oxides. The technology applied leads to formation of nanostructures composed by nanoparticles....
Article
A laser-based technology is presented for fabrication of oriented nanowires composed by nanoparticles. The nanowires were produced by nanosecond pulsed laser deposition in air at atmospheric pressure in the presence of an external magnetic field. The technology described is relevant to the preparation of nanowires of magnetic materials. Applying an...
Article
Full-text available
The present article investigates the mechanical properties and microstructure of the CrTiAlN thin coatings obtained at a low deposition temperature (150°C) using Closed Field Unbalanced Magnetron Sputtering (CFUBMS) technique onto different substrates. In order to determine the effect of heat treatment on mechanical and structural properties, the a...
Article
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A multilayer CrN/TiN coating was developed and deposited onto high speed steel (HSS) specimens by unbalanced magnetron sputtering in a closed-field magnetron configuration at a temperature lower than 200 o C from Cr (99.99 %) and Ti (99.99%) targets. Multilayers were deposited at different nitrogen partial pressure, a target current ratio ranged fr...
Article
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Nanostructures of noble metal were produced by pulsed laser ablation in liquid. A solid Ag target was immersed in double distilled water and a CuBr laser in a master oscillator—power amplifier configuration oscillating at 511 nm and emitting pulses with duration of 30 ns at a repetition rate of up to 20 kHz was employed to produce different colloid...
Article
Full-text available
The paper presents a study on the fabrication of ZnO nanostructures by applying a pulsed laser deposition technique in air at atmospheric pressure (in open air). The laser ablation of a ZnO target was performed by a nanosecond Nd:YAG laser system operated at the wavelengths of 355, 532 and 1064 nm. In open air, the ablation process leads to a direc...
Article
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ZnO nanostructures were fabricated on noble-metal (Au-Ag alloy) coated substrates by pulsed laser deposition. We studied the influence of the laser wavelength used for ablation on the morphology, growth mechanism, and optical properties of the nanostructures. ZnO nanostructures produced by UV (355 nm) pulsed laser deposition possessed a mixed-struc...
Article
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This work demonstrates nanostructures deposition using nanosecond and femtosecond laser ablation in air. The laser parameters correspond the most common laser systems—Nd:YAG, operated at 1064 and 532 nm and Ti:Sapphire at 800 nm. In the case of nanosecond pulses, the deposited material forms a complex structure that is composed by microsized drople...
Article
High surface area mesoporous ceria-titania binary materials with high Lewis acidity and improved reduction properties were synthesized using template assisted hydrothermal technique. The obtained materials were characterized by low temperature nitrogen physisorption, XRD, SEM, TEM, Raman, UV-Vis, XPS, FTIR, FTIR of adsorbed pyridine and thermo-prog...
Article
Zirconia nanomaterials were prepared by hydrothermal synthesis with or without template and were modified by post synthesis method with sulfate groups. The materials were thoroughly characterized by X-ray powder diffraction, TEM, N2 physisorption, FTIR spectroscopy of adsorbed pyridine TG analysis and XPS spectroscopy. The catalytic performance of...
Article
Mesostructured silica-carbon composites were synthesized by soft template approach and were characterized by TG, XRD, low temperature N2- adsorption, TEM, XPS. The CO2 adsorption capacities were investigated and the heats of adsorption were determined. The CO2 capture from flue gas was tested. The carbon-containing materials exhibit better performa...
Article
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Recently ordered mesoporous silicas have been considered as suitable catalyst supports due to their high surface area, well developed porous volume and tuned size, shape and topology of mesopores. Among them SBA-15 and KIT-6 are most promising and studied materials as host matrix of metal/metal oxide nanoparticles. Both structures are characterized...
Article
Zirconia nanomaterials were prepared by impregnation of KIL-2 type silica with 4, 8, 15 and 25 wt.% of ZrO2, and were modified by sulfate groups in order to vary the type, strength and density of the active sites. The samples were characterized by X-ray powder diffraction (XRD), EDX analysis, N2 physisorption, SEM, TEM, UV-Vis spectroscopy, XPS, an...
Article
Full-text available
The development of lithium and sodium ion batteries without using lithium and sodium metal as anodes gives the impetus for elaboration of low-cost and environmentally friendly energy storage devices. In this contribution we demonstrate the design and construction of a new type of hybrid sodium-lithium ion cell by using unique electrode combination...
Article
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In the present work, thin zirconia films were prepared by pulsed laser deposition at different substrate temperatures and oxygen partial pressures. The substrate temperature was varied from 400 °C to 600 °C, and the oxygen pressure, from 0.01 to 0.05 mbar. The effect was investigated of the substrate temperature and oxygen pressure on the formation...
Article
Copper catalysts supported on two types of silica–carbon composites- with ordered and with disordered architecture were investigated in reactions of NOx elimination. Disordered silica-carbons were prepared by sol–gel method and ordered composites by tri-constituent co-assembly of resol, silica oligomers and triblock copolymer. Two Si/C ratios were...
Article
Zinc oxide particles with various morphologies were successfully prepared via three synthesis methods: precipitation; tribophysical treatment and sonochemistry. The as-synthesized samples were characterized by X-ray diffraction (XRD); infrared spectroscopy (IR); scanning electron microscope (SEM); BET specific surface area; electron-paramagnetic re...
Article
Full-text available
Silver- or nickel-loaded activated carbon (AC) catalysts were prepared by impregnation, and subsequent physicochemical pyrolysis and activation by continuous blowing of exhausted gas through the sample and addition of water vapor to the feed. The X-ray diffraction pattern of the catalyst samples included peaks characteristic of metallic Ago and Nio...
Article
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Cobalt-silica-carbon composites were prepared by sol-gel method and tested as catalysts for NO reduction by CO. Active carbons of different texture parameters were used for synthesis of these composites. A cobalt-silica composite was also prepared for comparison purposes. The catalysts were characterized by low-temperature nitrogen adsorption, X-ra...
Article
Full-text available
Different types of ZnO nanostructures were fabricated on metal (Au or Ag) coated silicon substrates by applying the pulsed laser deposition (PLD) method. The samples were prepared at substrate temperatures in the range of 300 - 650 °C, oxygen pressure of 5 Pa, and laser fluence ≤ 1 J.cm-2 - process parameters usually used for thin-film deposition....
Article
Full-text available
In this work, ZnO nanostructures were fabricated on metal (a metal alloy containing Fe, Cr, Mn and Ni) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at substrate temperatures in the range of 550 – 650 °C, oxygen pressure of 5 Pa, and laser fluence ≤ 1 J cm−2 i.e., process parameters usually used for thin-f...
Conference Paper
Full-text available
The composition and structure of TiAl-based metallizations have been investigated depending on the Ti and Mo barriers. It is found out that the contact resistivity depends mainly on the Ti/Al ratio. The lowest contact resistivity of 4×10-6 Q.cm2 for a Ti barrier and 7×10-6 Q.cm2 for a Mo barrier is obtained at a Ti/Al ratio of 0.43 after annealing...
Article
Copper and cerium bi-component modifications of KIT-6 were prepared by wetness impregnation technique from the corresponding nitrate precursors. Nitrogen physisorption, XRD, FTIR of adsorbed CO, UV-Vis, XPS and TPR were used for their characterization. The catalytic activity of the obtained materials was tested in ethyl acetate oxidation and compar...
Article
Full-text available
In this work we report the results of investigation of silver (Ag) nanoparticles prepared on a silica substrate by laser ablation. Our attention was focused on the mean diameter, size distribution and optical absorption properties of nanoparticles prepared in vacuum by using different laser wavelengths. The fundamental wavelength and the second, th...
Article
First time a combined wet impregnation (WI)-organometallics chemical vapor deposition (OMCVD) strat-egy was applied for loading of 3–7 wt.% copper in mesoporous silica KIT-6 matrix nanoparticles withtailored particle size. XRD, HRTEM, nitrogen physisorption, UV–vis, XPS and temperature programmedreduction with hydrogen were used for the samples cha...
Article
Full-text available
The composite nanostructures of double layer, multilayer and mosaic Ag/ZnO containing nano-sized particles have been produced by laser deposition and annealing procedures. The samples are investigated and the results indicated that laser annealing of Ag or Ag/ZnO layer is a feasible method to tune the optical properties of the nanostructures. Their...
Article
Copper and cerium oxide bi-component materials with different Cu/Ce ratio were prepared using ordered SBA-15 silica as a support and compared with their bulk analogs. The samples were characterized by nitrogen physisorption, XRD, UV-Vis, FTIR, XPS, Raman spectroscopy and TPR with hydrogen. Cyclohexanol conversion was used as a catalytic test to obt...
Article
Full-text available
A 90 wt.% MgH2 - 10 wt.% V2O5 composite was obtained by ball milling of a mixture of magnesium hydride and vanadia for 60 min under argon. Hydrogen sorption properties of the composite were determined volumetrically with a Sieverts-type device. Absorption was studied at temperatures of 473 and 573 K and pressure of 1 MPa, while desorption was inves...
Article
Full-text available
The subject of the present work is different types of nanostructured ZnO films produced by pulsed laser deposition. The influence was investigated of the surface morphology on the physicochemical and optical properties of the nanostructured films. X-ray photoelectron spectroscopy was used to study the composition and chemical state of the nanostruc...
Article
Full-text available
Thin ZnO nanostructured films were produced by pulsed laser deposition (PLD) for surface enhanced Raman spectroscopy (SERS) studies. The experimental conditions used for preparation of the samples were chosen to obtain different types of ZnO nanostructures. The Raman spectra of rhodamine 6G (R6G) were measured at an excitation wavelength of 785 nm...
Article
Full-text available
This work is focused on the study of corrosion-protection ability of the thin ceria film, formed electrochemically on OC404 stainless steel (SS) in non-aqueous electrolytes. The influence of changes in the surface concentration of Ce2O3-CeO2 on the corrosion behaviour of OC404 stainless steel in 3.5% NaCl was investigated prior to the thermal treat...
Article
Full-text available
In this study, we explored the possibility of the preparation of a catalytic system for reduction of nitrogen oxides based on alumina and zirconia thin films electrochemically deposited on stainless steel, silver being chosen as an active phase. The composition and structure of the Ag loaded Al2O3/SS and ZrO2/SS films were characterized by SEM, XPS...
Article
In this work, thin ZnO films were produced by pulsed laser deposition on a side-polished single-mode fiber in view of optical gas sensor applications. The experimental conditions used for preparation of the samples were chosen so as to obtain smooth, porous and nanostructured films. The influence of the film structure on the sensitivity to ammonia...
Article
Full-text available
In the present work, the surface properties of various Al oxide films were investigated. The oxide films were produced on a stainless steel by spray pyrolysis and cathodic deposition methods. The films obtained represent typical layers that can be used as a support in model systems to investigate alumina-based catalysts. Information about the chemi...
Article
Full-text available
SnO2 thin films for gas sensing applications were deposited by RF sputtering in a mixture of oxygen and argon. The morphology, structure and composition of the SnO2 films were analysed by XRD, SEM and XPS. SnO2 thin films showed a crystalline structure with a submicron particle size of 200 nm. The electronic structure of the film surface was elucid...
Article
Full-text available
A comparative investigation has been carried out on the corrosion behaviour of thermally treated stainless steel (SS) OC4004 covered with Al 2O3 or Ce2O3-CeO2 layers (systems Al2O3/SS(t.t.) and Ce 2O3-CeO2/SS(t.t.)) electrodeposited on in solutions of 0.1 N HNO3 and 0.1 N H2SO4. It has been established that in NO3 containing medium SS (t.t.) tends...
Article
Two platinum-containing zeolites were studied by XPS, TPR and IR spectroscopy of adsorbed CO. The sample Pt–NaY was prepared by ion-exchange and the Pt/NaY sample, by impregnation. XP spectra indicate a higher heterogeneity of platinum on the impregnated sample and enrichment of its outer surface in platinum, compared to the exchanged sample. Acces...
Article
Alumina is widely employed as support of noble-metal automotive exhaust catalysts. With a view to practical use in catalytic converters, an electrochemical method for deposition of Al2O3 coatings on thin foils of stainless steel was developed. The coatings were deposited from AlCl3 diluted in alcohol solutions. The deposition experiments were perfo...
Article
This work presents a new electrochemical method (i.e. new electrolyte composition and electrolysis regimes) for direct formation of Al2O3 on different metal substrates from non-aqueous electrolytes, data on the kinetics of the electrochemical processes and scanning electron microscopy (SEM) and XPS studies of the morphology, structure, dispersion a...
Article
A new electrochemical method using a non-aqueous electrolyte was utilized for deposition of cerium oxide layers on different substrates. X-Ray photoelectron spectroscopy was used to examine the nature of cathodically deposited cerium thin films on stainless steel (SS), ZrO2/SS and Al2O3/SS substrates as a function of the preparation conditions and...
Article
Full-text available
This paper reports the preparation and characterization of Co/ZrO2 thin film catalysts. ZrO2 thin films (SBET∼25 m2 g-1) have been prepared at low temperature by magnetron sputtering. This procedure is typically used to get compact thin films and has been modified to prepare porous catalyst layers. The obtained results prove that this can be an int...
Article
This work presents a new electrochemical method (i.e. new electrolyte composition and electrolysis regime) for direct formation of La2O3 on ZrO2 and other oxide and metal substrates from nonaqueous electrolytes, data on the kinetics of the electrochemical processes and scanning electron microscopy (SEM) and XPS studies of the morphology, structure,...
Article
Thin Co/ZrO2 and Co/S-ZrO2 catalytic films for hydrocarbon-selective catalytic reduction (HC-SCR) of NOx were prepared and characterized by means of XPS, SEM and scanning Auger microscopy (SAM). Zirconia was deposited on a fibrous inconel support (Bekaert) by the sol–gel method. Cobalt was deposited on pure and pre-sulphated zirconia films by impre...