Florian Dumitrache - Academia.edu (original) (raw)
Papers by Florian Dumitrache
Molecules
The purpose of this study was to investigate the synthesis of iron oxide nanoparticles under two ... more The purpose of this study was to investigate the synthesis of iron oxide nanoparticles under two different conditions, namely high and low gas flow rates, using laser pyrolysis and to examine the influence of laser power. The attained nanoparticles have been characterised regarding their stability and hydrodynamic dimensions by dispersive light scattering analysis (DLS), structure–X-ray diffraction (XRD), elemental composition–energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and morpho-structural characterisation achieved by transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). For a better understanding of the laser power influence, the residence time was also calculated.
Journal of Materials Science and Chemical Engineering, 2019
The sacrificial polymeric template usually used in lithographic methods could be replaced by crys... more The sacrificial polymeric template usually used in lithographic methods could be replaced by crystalline materials such as ionic salts which, in some special conditions, can form arrays of single crystals. Atomic force microscopy investigations performed on such samples show their regularity and nanometric thickness. They can serve as a part of an ionic/molecular crystal grid or as mask in crystal lithography. Alternating the polarity degree of the employed solvents/dispersing media by matching materials qualities, we fabricated a sodium chromate and sulphur crystalline net, iron oxide nanoparticle grid and a sulphur single crystal array. The lack of any expensive/sophisticated technology in the production process of final devices makes this approach attractive.
Journal of Nanomaterials, 2010
Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and ... more Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and methyl methacrylate (MMA) mixtures. The morphology of nanopowder analyzed by TEM indicated that mainly core-shell structures were obtained. X-ray diffraction techniques evidence the cores as formed mainly by iron/iron oxide crystalline phases. A partially degraded (carbonized) polymeric matrix is suggested for the coverage of the metallic particles. The nanocomposite structure at the variation of the laser density and of the MMA flow was studied. The new materials prepared as thick films were tested for their potential for acting as gas sensors. The temporal variation of the electrical resistance in presence ofNO2, CO, andCO2, in dry and humid air was recorded. Preliminary results show that the samples obtained at higher laser power density exhibit rather high sensitivity towardsNO2detection andNO2selectivity relatively to CO andCO2. An optimum working temperature of200°Cwas found.
Carbon-made materials have been the field of major discoveries with the identification of new pha... more Carbon-made materials have been the field of major discoveries with the identification of new phases, which have stimulated a huge effort to understand their properties. Laser pyrolysis of hydrocarbons is based on a high temperature C/H/O/... system of well-established composition and allows obtaining carbon nanostructures from the almost amorphous carbon and particles with a turbostratic structure up to those characterized
SPIE Proceedings, 2004
The embedding of Fe-based nanoparticles in carbon layers allows novel physical and catalyzing pro... more The embedding of Fe-based nanoparticles in carbon layers allows novel physical and catalyzing properties due to inertness and resistance to external detrimental conditions. We have prepared almost spherical carbon encapsulated iron nanoparticles with narrow size distribution, via laser co-pyrolysis method in which the CW CO2 laser beam irradiates a gas mixture containing iron pentacarbonyl (vapors) and ethylene/acetylene hydrocarbons. Specific flow geometries were used in order to synthesize iron particle first followed by stimulate hydrocarbon decomposition at iron surfaces. High-resolution transmission electron microscopy images reveal the core-shell feature of synthesized nanostructures with around 2 nm thick carbon layers and 3-7 nm diameters iron-based core dimensions. The mean diameter could be experimentally controlled. It was found a decreasing trend of particle size with the decreasing of pressure and total reactant gas flow. EELS, EDAX and Raman spectroscopy analysis confirm the simultaneous presence of carbon and iron. The nanoparticles were seeded onto Si wafer and further used as substrates for laser induced CVD carbon nanotubes growth. Depending on laser power density, nanotubes or nanofibres are formed, in strong dependence with the location of iron based nanoparticles on Si substrates as revealed by SEM analysis.
We describe our low spectral resolution Raman system that allows us to directly appreciate the qu... more We describe our low spectral resolution Raman system that allows us to directly appreciate the quality of YBa2Cu3O7-delta (YBCO) films, obtained by pulsed laser deposition on LaAlO3 substrate. We identify the basic features of YBCO films' spectral fingerprints, validated by high spectral resolution analysis, described in previous reports. This fast and nondestructive valuable analytical tool functions at a convenient time
Laser pyrolysis of a hydrocarbon-based mixture is a continuous method for the synthesis of soot-c... more Laser pyrolysis of a hydrocarbon-based mixture is a continuous method for the synthesis of soot-containing fullerene. In this synthesis process, the mechanism of fullerene formation and soot is the radical mechanism of the PAH formation. In the flames producing both fullerenes and soot, exactly forming carbon cages require particular types of reaction sequences. The fullerene concentrations are strongly correlated with
SPIE Proceedings, 2008
The structural properties and morphology of ZnO nanoparticles obtained by hydrothermal method wer... more The structural properties and morphology of ZnO nanoparticles obtained by hydrothermal method were studied. ZnO samples were obtained by hydrothermal method, in soft synthesis conditions, temperature of solution about 70°C, in presence of a bidentate ligand or a tensioactive agent. The resulted oxides morphologies were compared with the morphologies of ZnO samples obtained in absence of ligands or tensioactive agents.
SPIE Proceedings, 2004
TiO2 nano powder was prepared by laser pyrolysis of gas phase reactants. TiCl4 (vapor) was used a... more TiO2 nano powder was prepared by laser pyrolysis of gas phase reactants. TiCl4 (vapor) was used as titanium precursor. The crystalline structures and morphologies of the powder have been analyzed by transmission electron microscopy (TEM), selected area electron diffraction (SAD) and Raman spectrometry. The different characterization techniques suggest that a nano-crystalline mixture of anatase and rutile is obtained.
Soots obtained by laser pyrolysis of different gaseous/vapor hydrocarbons were investigated. The ... more Soots obtained by laser pyrolysis of different gaseous/vapor hydrocarbons were investigated. The morphology variation of carbon soot versus process parameters and nature of reactants was analyzed and discussed. The role of oxygen is essential in obtaining soot particles having considerable curved-layer content.
2003 IEEE International Workshop on Workload Characterization (IEEE Cat. No.03EX775)
Abstract Different kind of nanometric powders: carbon, iron, titanium oxide or composites like: F... more Abstract Different kind of nanometric powders: carbon, iron, titanium oxide or composites like: Fe/Ti, C/Fe, were obtained by laser pyrolysis of some specific precursors. All of these powders have the ability to float on water. In a good analogy with Langmuir-Blodgett ...
Physica E: Low-dimensional Systems and Nanostructures, 2008
Iron-based nanocomposites were synthesized by the CO2 laser-induced co-pyrolysis of Fe(CO)5 and [... more Iron-based nanocomposites were synthesized by the CO2 laser-induced co-pyrolysis of Fe(CO)5 and [(CH3)3Si]2O (HMDSO) vapors. The obtained nanoparticles exhibited an iron-based core surrounded by an organosilicon polymer shell. Particles having different thicknesses of the polymer shell were deposited by either a spin-coating or by a drop-casting method on Si(100) substrates. Carbon nanotubes (CNTs) were grown by dc plasma-assisted and filaments-activated
Nanotechnology, 2004
Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively... more Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively, air and nitrous oxide were used as oxygen precursors. C2H4 was used as an energy transfer agent. The underlying phenomena for this photon-based molecular nanotechnology are discussed. For the present report, different titania nanosized powder batches were obtained by variation of the oxidizer nature and TiCl4 precursor flows.
Journal of Nanoscience and Nanotechnology, 2012
The synthesis of iron doped tin oxide by pulsed laser pyrolysis is reported. The as obtained nano... more The synthesis of iron doped tin oxide by pulsed laser pyrolysis is reported. The as obtained nanoparticles have a dominant Sn02 phase (as revealed by Wide Angle X-ray Scattering), with particles of the order of 10 nm. The doping with iron or iron oxide triggers magnetic properties as confirmed by SQUID experiments. EDX measurements supported the presence of Fe while Wide Angle X-ray Scattering failed to sense any iron or iron-oxide phase. It is concluded that Fe is well dispersed within the tin-oxide nanoparticles. The coercitive field has a complex dependence on the Fe/Sn content suggesting that the magnetization is not controlled solely by the amount of Fe dispersed within the nanoparticles.
Applied Surface Science, 2005
Iron-based core-shell nanostructures were synthesized by laser pyrolysis in a two-steps procedure... more Iron-based core-shell nanostructures were synthesized by laser pyrolysis in a two-steps procedure. In a first step, using a cross-flow configuration, the laser radiation was heating a gas phase mixture containing iron pentacarbonyl (vapors) entrained by an ethylene flow, which plays also the role of an energy transfer agent. Secondly, a carefully controlled in situ passivation of the freshly formed pyrophoric iron nanoparticles created a protective iron oxide shell. The produced nanoparticles (22 nm size diameters) with core-shell features were analyzed by TEM, XRD, SAED and Raman spectroscopy. Majoritary iron and gamma iron oxide/magnetite and minoritary carbon phases were identified. In laser pyrolysis experiments in which the reaction temperature was increased, the catalyzed homogeneous nucleation and growth of carbon nanotubes in the gas phase was observed and is presented here for the first time.
Applied Surface Science, 2007
Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process.... more Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe 2 O 3 (maghemite/magnetite) particles with sizes ::;5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO 2 /Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma-and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/mm.
Applied Surface Science, 2013
Present work was focused on producing improved iron oxide nanoparticles for targeted drug deliver... more Present work was focused on producing improved iron oxide nanoparticles for targeted drug delivery in breast cancer. Nanometric-sized iron oxide particles were synthesized by laser pyrolysis and were morphologically/structurally characterized. These new nanoparticles were compared with some commercial, chemically prepared iron oxide ones. Cytotoxicity and the anti-proliferation effects of nanoparticles were tested in vitro on the breast adenocarcinoma cell line MCF-7. Nanoparticles were further coated with the antracyclinic antibiotic Violamycine B1 and tested for the anti-tumor effect on MCF-7 cells. The nanoparticles produced by us seem more effective in vitro than the commercial ones, with respect to cellular uptake and VB1 delivery. Violamycine B1 bound on nanoparticles is as efficient as the free form, but is better delivered into tumor cells.
Applied Organometallic Chemistry, 2005
... nano-ironpolyoxocarbosilane composites Josef Pola1*, Miroslav Maryˇsko2, Vladimır Vorlıˇcek2... more ... nano-ironpolyoxocarbosilane composites Josef Pola1*, Miroslav Maryˇsko2, Vladimır Vorlıˇcek2, Zden ˇek Bastl3, Anna Galıkov ´a1, Karel Vacek1, Rodica Alexandrescu4**,Florian Dumitrache4, Ion Morjan4, Lavinia Albu4 and Gabriel Prodan5 ...
Advanced Powder Technology, 2012
Iron-carbon nanocomposites have gained interest due to their new engineering and biomedical appli... more Iron-carbon nanocomposites have gained interest due to their new engineering and biomedical applications. Carbon coated iron nanoparticles (Fe@C) were obtained continuously and in a single step using the laser pyrolysis method. The continuous wave CO 2 laser beam was used to continuously heat a sensitized (with ethylene) precursor gas mixture, in which iron pentacarbonyl (vapor) and acetylene were the iron and carbon donors, respectively. The effect of varying the residence time in the reaction zone through the variation of the internal nozzle diameter was explored in order to improve the particle size and the phase distributions. At increased nozzle diameter, (i) the particle mean diameter increases (from about 3.5 to 10.5 nm), (ii) higher ordering of the crystallographic network seems to occur, (iii) the dominance of the a-Fe and iron carbide phases is revealed. Onion-like graphenic layers often cover the buried iron cores. Magnetic measurements and temperature dependent Mössbauer spectroscopy were used in order to find correlations concerning the magnetic behavior and the Fe phase composition of samples. Preliminary experiments for obtaining stable water-based magnetic nanofluids are discussed.
Molecules
The purpose of this study was to investigate the synthesis of iron oxide nanoparticles under two ... more The purpose of this study was to investigate the synthesis of iron oxide nanoparticles under two different conditions, namely high and low gas flow rates, using laser pyrolysis and to examine the influence of laser power. The attained nanoparticles have been characterised regarding their stability and hydrodynamic dimensions by dispersive light scattering analysis (DLS), structure–X-ray diffraction (XRD), elemental composition–energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and morpho-structural characterisation achieved by transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). For a better understanding of the laser power influence, the residence time was also calculated.
Journal of Materials Science and Chemical Engineering, 2019
The sacrificial polymeric template usually used in lithographic methods could be replaced by crys... more The sacrificial polymeric template usually used in lithographic methods could be replaced by crystalline materials such as ionic salts which, in some special conditions, can form arrays of single crystals. Atomic force microscopy investigations performed on such samples show their regularity and nanometric thickness. They can serve as a part of an ionic/molecular crystal grid or as mask in crystal lithography. Alternating the polarity degree of the employed solvents/dispersing media by matching materials qualities, we fabricated a sodium chromate and sulphur crystalline net, iron oxide nanoparticle grid and a sulphur single crystal array. The lack of any expensive/sophisticated technology in the production process of final devices makes this approach attractive.
Journal of Nanomaterials, 2010
Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and ... more Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and methyl methacrylate (MMA) mixtures. The morphology of nanopowder analyzed by TEM indicated that mainly core-shell structures were obtained. X-ray diffraction techniques evidence the cores as formed mainly by iron/iron oxide crystalline phases. A partially degraded (carbonized) polymeric matrix is suggested for the coverage of the metallic particles. The nanocomposite structure at the variation of the laser density and of the MMA flow was studied. The new materials prepared as thick films were tested for their potential for acting as gas sensors. The temporal variation of the electrical resistance in presence ofNO2, CO, andCO2, in dry and humid air was recorded. Preliminary results show that the samples obtained at higher laser power density exhibit rather high sensitivity towardsNO2detection andNO2selectivity relatively to CO andCO2. An optimum working temperature of200°Cwas found.
Carbon-made materials have been the field of major discoveries with the identification of new pha... more Carbon-made materials have been the field of major discoveries with the identification of new phases, which have stimulated a huge effort to understand their properties. Laser pyrolysis of hydrocarbons is based on a high temperature C/H/O/... system of well-established composition and allows obtaining carbon nanostructures from the almost amorphous carbon and particles with a turbostratic structure up to those characterized
SPIE Proceedings, 2004
The embedding of Fe-based nanoparticles in carbon layers allows novel physical and catalyzing pro... more The embedding of Fe-based nanoparticles in carbon layers allows novel physical and catalyzing properties due to inertness and resistance to external detrimental conditions. We have prepared almost spherical carbon encapsulated iron nanoparticles with narrow size distribution, via laser co-pyrolysis method in which the CW CO2 laser beam irradiates a gas mixture containing iron pentacarbonyl (vapors) and ethylene/acetylene hydrocarbons. Specific flow geometries were used in order to synthesize iron particle first followed by stimulate hydrocarbon decomposition at iron surfaces. High-resolution transmission electron microscopy images reveal the core-shell feature of synthesized nanostructures with around 2 nm thick carbon layers and 3-7 nm diameters iron-based core dimensions. The mean diameter could be experimentally controlled. It was found a decreasing trend of particle size with the decreasing of pressure and total reactant gas flow. EELS, EDAX and Raman spectroscopy analysis confirm the simultaneous presence of carbon and iron. The nanoparticles were seeded onto Si wafer and further used as substrates for laser induced CVD carbon nanotubes growth. Depending on laser power density, nanotubes or nanofibres are formed, in strong dependence with the location of iron based nanoparticles on Si substrates as revealed by SEM analysis.
We describe our low spectral resolution Raman system that allows us to directly appreciate the qu... more We describe our low spectral resolution Raman system that allows us to directly appreciate the quality of YBa2Cu3O7-delta (YBCO) films, obtained by pulsed laser deposition on LaAlO3 substrate. We identify the basic features of YBCO films' spectral fingerprints, validated by high spectral resolution analysis, described in previous reports. This fast and nondestructive valuable analytical tool functions at a convenient time
Laser pyrolysis of a hydrocarbon-based mixture is a continuous method for the synthesis of soot-c... more Laser pyrolysis of a hydrocarbon-based mixture is a continuous method for the synthesis of soot-containing fullerene. In this synthesis process, the mechanism of fullerene formation and soot is the radical mechanism of the PAH formation. In the flames producing both fullerenes and soot, exactly forming carbon cages require particular types of reaction sequences. The fullerene concentrations are strongly correlated with
SPIE Proceedings, 2008
The structural properties and morphology of ZnO nanoparticles obtained by hydrothermal method wer... more The structural properties and morphology of ZnO nanoparticles obtained by hydrothermal method were studied. ZnO samples were obtained by hydrothermal method, in soft synthesis conditions, temperature of solution about 70°C, in presence of a bidentate ligand or a tensioactive agent. The resulted oxides morphologies were compared with the morphologies of ZnO samples obtained in absence of ligands or tensioactive agents.
SPIE Proceedings, 2004
TiO2 nano powder was prepared by laser pyrolysis of gas phase reactants. TiCl4 (vapor) was used a... more TiO2 nano powder was prepared by laser pyrolysis of gas phase reactants. TiCl4 (vapor) was used as titanium precursor. The crystalline structures and morphologies of the powder have been analyzed by transmission electron microscopy (TEM), selected area electron diffraction (SAD) and Raman spectrometry. The different characterization techniques suggest that a nano-crystalline mixture of anatase and rutile is obtained.
Soots obtained by laser pyrolysis of different gaseous/vapor hydrocarbons were investigated. The ... more Soots obtained by laser pyrolysis of different gaseous/vapor hydrocarbons were investigated. The morphology variation of carbon soot versus process parameters and nature of reactants was analyzed and discussed. The role of oxygen is essential in obtaining soot particles having considerable curved-layer content.
2003 IEEE International Workshop on Workload Characterization (IEEE Cat. No.03EX775)
Abstract Different kind of nanometric powders: carbon, iron, titanium oxide or composites like: F... more Abstract Different kind of nanometric powders: carbon, iron, titanium oxide or composites like: Fe/Ti, C/Fe, were obtained by laser pyrolysis of some specific precursors. All of these powders have the ability to float on water. In a good analogy with Langmuir-Blodgett ...
Physica E: Low-dimensional Systems and Nanostructures, 2008
Iron-based nanocomposites were synthesized by the CO2 laser-induced co-pyrolysis of Fe(CO)5 and [... more Iron-based nanocomposites were synthesized by the CO2 laser-induced co-pyrolysis of Fe(CO)5 and [(CH3)3Si]2O (HMDSO) vapors. The obtained nanoparticles exhibited an iron-based core surrounded by an organosilicon polymer shell. Particles having different thicknesses of the polymer shell were deposited by either a spin-coating or by a drop-casting method on Si(100) substrates. Carbon nanotubes (CNTs) were grown by dc plasma-assisted and filaments-activated
Nanotechnology, 2004
Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively... more Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively, air and nitrous oxide were used as oxygen precursors. C2H4 was used as an energy transfer agent. The underlying phenomena for this photon-based molecular nanotechnology are discussed. For the present report, different titania nanosized powder batches were obtained by variation of the oxidizer nature and TiCl4 precursor flows.
Journal of Nanoscience and Nanotechnology, 2012
The synthesis of iron doped tin oxide by pulsed laser pyrolysis is reported. The as obtained nano... more The synthesis of iron doped tin oxide by pulsed laser pyrolysis is reported. The as obtained nanoparticles have a dominant Sn02 phase (as revealed by Wide Angle X-ray Scattering), with particles of the order of 10 nm. The doping with iron or iron oxide triggers magnetic properties as confirmed by SQUID experiments. EDX measurements supported the presence of Fe while Wide Angle X-ray Scattering failed to sense any iron or iron-oxide phase. It is concluded that Fe is well dispersed within the tin-oxide nanoparticles. The coercitive field has a complex dependence on the Fe/Sn content suggesting that the magnetization is not controlled solely by the amount of Fe dispersed within the nanoparticles.
Applied Surface Science, 2005
Iron-based core-shell nanostructures were synthesized by laser pyrolysis in a two-steps procedure... more Iron-based core-shell nanostructures were synthesized by laser pyrolysis in a two-steps procedure. In a first step, using a cross-flow configuration, the laser radiation was heating a gas phase mixture containing iron pentacarbonyl (vapors) entrained by an ethylene flow, which plays also the role of an energy transfer agent. Secondly, a carefully controlled in situ passivation of the freshly formed pyrophoric iron nanoparticles created a protective iron oxide shell. The produced nanoparticles (22 nm size diameters) with core-shell features were analyzed by TEM, XRD, SAED and Raman spectroscopy. Majoritary iron and gamma iron oxide/magnetite and minoritary carbon phases were identified. In laser pyrolysis experiments in which the reaction temperature was increased, the catalyzed homogeneous nucleation and growth of carbon nanotubes in the gas phase was observed and is presented here for the first time.
Applied Surface Science, 2007
Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process.... more Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe 2 O 3 (maghemite/magnetite) particles with sizes ::;5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO 2 /Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma-and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/mm.
Applied Surface Science, 2013
Present work was focused on producing improved iron oxide nanoparticles for targeted drug deliver... more Present work was focused on producing improved iron oxide nanoparticles for targeted drug delivery in breast cancer. Nanometric-sized iron oxide particles were synthesized by laser pyrolysis and were morphologically/structurally characterized. These new nanoparticles were compared with some commercial, chemically prepared iron oxide ones. Cytotoxicity and the anti-proliferation effects of nanoparticles were tested in vitro on the breast adenocarcinoma cell line MCF-7. Nanoparticles were further coated with the antracyclinic antibiotic Violamycine B1 and tested for the anti-tumor effect on MCF-7 cells. The nanoparticles produced by us seem more effective in vitro than the commercial ones, with respect to cellular uptake and VB1 delivery. Violamycine B1 bound on nanoparticles is as efficient as the free form, but is better delivered into tumor cells.
Applied Organometallic Chemistry, 2005
... nano-ironpolyoxocarbosilane composites Josef Pola1*, Miroslav Maryˇsko2, Vladimır Vorlıˇcek2... more ... nano-ironpolyoxocarbosilane composites Josef Pola1*, Miroslav Maryˇsko2, Vladimır Vorlıˇcek2, Zden ˇek Bastl3, Anna Galıkov ´a1, Karel Vacek1, Rodica Alexandrescu4**,Florian Dumitrache4, Ion Morjan4, Lavinia Albu4 and Gabriel Prodan5 ...
Advanced Powder Technology, 2012
Iron-carbon nanocomposites have gained interest due to their new engineering and biomedical appli... more Iron-carbon nanocomposites have gained interest due to their new engineering and biomedical applications. Carbon coated iron nanoparticles (Fe@C) were obtained continuously and in a single step using the laser pyrolysis method. The continuous wave CO 2 laser beam was used to continuously heat a sensitized (with ethylene) precursor gas mixture, in which iron pentacarbonyl (vapor) and acetylene were the iron and carbon donors, respectively. The effect of varying the residence time in the reaction zone through the variation of the internal nozzle diameter was explored in order to improve the particle size and the phase distributions. At increased nozzle diameter, (i) the particle mean diameter increases (from about 3.5 to 10.5 nm), (ii) higher ordering of the crystallographic network seems to occur, (iii) the dominance of the a-Fe and iron carbide phases is revealed. Onion-like graphenic layers often cover the buried iron cores. Magnetic measurements and temperature dependent Mössbauer spectroscopy were used in order to find correlations concerning the magnetic behavior and the Fe phase composition of samples. Preliminary experiments for obtaining stable water-based magnetic nanofluids are discussed.