rachid bensalem - Academia.edu (original) (raw)
Papers by rachid bensalem
Mechanical alloying was used to prepare the like amorphous (FeCo) 62 Nb 8 B 30 alloy from pure el... more Mechanical alloying was used to prepare the like amorphous (FeCo) 62 Nb 8 B 30 alloy from pure elemental Fe, Co, Nb and B powders. The structural and thermal properties were investigated by X-ray diffraction and differential scanning calorimetry. During the first stage of milling, it is observed the formation of metastable Fe-borides such as fcc-Fe 23 B 6 and tetragonal Fe 3 B-type phases. Calorimetric scans of the milled powder for 125 h shows one exothermic peak related to the primary nanocrystallization of the α-FeCo phase.
Nanocrystalline Fe10 %Zn and Fe30 %Zn alloys have been prepared from pure elemental powders by me... more Nanocrystalline Fe10 %Zn and Fe30 %Zn alloys have been prepared from pure elemental powders by mechanical alloying processing in a high energy planetary ball-mill. Microstructural, structural, and mag-netic characterizations of the powders were investigated by X-ray diffraction, and vibrating sample mag-nometer. The crystallite size reduction to the nanometer scale is accompanied by an increase in the atomic level strain. The reaction between Fe and Zn leads to the formation of a bcc Fe(Zn) solid solution with a lattice parameter close to (0.2912 nm for Fe30 %Zn and 0,2885 nm for Fe10 %Zn) after 5 h of milling. The complete dissolution of the elemental Zn powders in the -Fe lattice gives rise to the formation of a highly disordered Fe(Zn) solid solution, where -Fe(Zn) nanograins have a crystallite size of (229,29 Å for Fe10 %Zn (24 h) 30,09 Å for Fe30 %Zn (24 h), on prolonged milling time. The coercivity and magnetization values are 18,90 (Fe10 %Zn)Oe and 26,59 (Fe30 %Zn) emu/g, r...
International Journal of Nanoparticles, 2010
... Ratheesh Kumar, PM, Sudha Kartha, C., Vijayakumar, KP, Singh, F. and Avasthi, DK (2005) &... more ... Ratheesh Kumar, PM, Sudha Kartha, C., Vijayakumar, KP, Singh, F. and Avasthi, DK (2005) 'Effect of fluorine doping on structural, electrical and ... Rodriguez-Baez, J., Maldonado, A., Castaneda, L., Torres Delgado, G., de la Castanedo-Pérez, R. and Olvera, L. (2007) 'On the ...
Surface and Coatings Technology, 2010
Partially amorphous Fe75Si15B10 coatings were prepared from nanostructured feedstock powders by u... more Partially amorphous Fe75Si15B10 coatings were prepared from nanostructured feedstock powders by using high velocity oxy-fuel spraying. Scanning electron microscopy, X-ray diffraction, Vickers indenter and magnetic measurements were used to investigate microstructural, structural, microhardness and magnetic properties of the coatings. The Rietveld refinement of the X-ray diffraction patterns reveals the presence of an amorphous phase, nanocrystalline α-Fe(Si,B) structure having a lattice
International Journal of Nanoparticles, 2011
Fe 61 Co 21 Nb 3 B 15 powder mixture was prepared by mechanical alloying process in a high energy... more Fe 61 Co 21 Nb 3 B 15 powder mixture was prepared by mechanical alloying process in a high energy planetary ball mill. Structural and thermal changes of the milled powders were followed by X-ray diffraction (XRD), Mössbauer spectrometry and differential scanning calorimetry (DSC). Both XRD and Mössbauer spectrometry results reveal the formation, after 48 h of milling, of a highly disordered amorphous-like structure where nanometer-sized iron borides were embedded. A mechanical recrystallisation process gives rise to the formation of α-Fe and α-FeCo nanograins on further milling. The occurrence of structural disorder in the milled powders might be confirmed by broad exothermic reaction in the DSC scans which consists of several overlapping exothermic peaks. Such behaviour originates from recovery, strain relaxation, grain growth and crystallisation.
ABSTRACT X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investi... more ABSTRACT X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate the phase identification and the thermal behaviour of the mechanically alloyed Fe57Co21Nb7B15 powders. The diffusion of B into the Nb lattice leads, after 1 h of milling, to the formation of a bcc Nb(B) solid solution with a lattice parameter close to a = 0.3425 nm. The solid state reaction between Fe and B gives rise to the formation of Fe23B6 and Fe2B boride phases after 3 and 6 h of milling, respectively. On further milling (96 h), an amorphous matrix (~80%), where nanocrystalline bcc α-Fe, bcc Nb(B), Fe2B and Fe3B phases were embedded, is obtained. The broad exothermic reaction in the DSC scans consists of several exothermic peaks and spreads over the entire temperature range 100–700°C. The enthalpy release at temperatures below 300°C can be attributed to recovery and strain relaxation. Crystallisation and grain growth are the dominating processes at high temperatures.
Energy Procedia, 2013
Equation of state (EOS) and other thermodynamic properties of Fe 2 B are studied using first-prin... more Equation of state (EOS) and other thermodynamic properties of Fe 2 B are studied using first-principles calculations based on the plane wave full potential density functional theory method within the generalized gradient approximation (GGA) for exchange and correlation. It is demonstrated that the ratio c/a of about 1.271 is the most stable structure for the Fe 2 B, which is consistent with the experimental data. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of the relative volume V/V 0 on pressure P, cell volume V, and on temperature T, are successfully obtained. The variations of the Debye temperature (V), the thermal expansion , and the heat capacity C V as a function of pressure P and temperature T, are investigated systematically in the ranges of 0-50 GPa and 0-1000 K.
International Journal of Nanoparticles, 2010
Elemental Fe and red phosphorus powders with a composition close to Fe-xP (x = 10, 15 and 20 wt. ... more Elemental Fe and red phosphorus powders with a composition close to Fe-xP (x = 10, 15 and 20 wt. %) were mechanically alloyed in a planetary ball mill under an argon atmosphere. Structural changes were studied by X-ray diffraction. The complete dissolution of the elemental powders is achieved within 3 h of milling. Detailed analysis of the X-ray diffraction patterns reveal the formation of a Fe(P) solid solution with two structures (α-Fe1 and α-Fe2) having different lattice parameters, crystallite size and microstrains in addition to FeP, Fe 2 P and Fe 3 P phosphides. The structural parameters and phase percentages are P content dependent.
physica status solidi (a), 2008
1 Laboratoire de Magnétisme et de Spectroscopie des Solides, Département de Physique, Faculté des... more 1 Laboratoire de Magnétisme et de Spectroscopie des Solides, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, 23000 Annaba, Algeria 2 CNRS-Laboratoire de Chimie Métallurgique des Terres Rares-Groupe des Laboratoires de Thiais, 28 Rue ...
Materials Chemistry and Physics, 2010
Mössbauer spectrometry and Rietveld analysis of X-ray diffraction patterns were used to follow th... more Mössbauer spectrometry and Rietveld analysis of X-ray diffraction patterns were used to follow the solid state amorphization transformation during the milling process of the Fe27.9Nb2.2B69.9 powders. The reaction between elemental Fe, Nb and B powders leads to the formation of the Nb(B) and Fe(B) solid solutions after 1 and 10h of milling, respectively. A mixture of α-Fe, Nb(B) and highly
Materials Chemistry and Physics, 2012
Partially amorphous Fe 57 Co 21 Nb 7 B 15 powder mixture was prepared by mechanical alloying in a... more Partially amorphous Fe 57 Co 21 Nb 7 B 15 powder mixture was prepared by mechanical alloying in a high energy planetary ball-mill under argon atmosphere. Thermal stability, magnetic properties, structural and morphological changes during the milling process were followed by differential scanning calorimetry, vibrating sample magnetometry, X-ray diffraction and scanning electron microscopy. A duplex nanostructure of Fe(Co) and Fe-boride nanocrystals within an amorphous matrix is achieved on further milling time. Depending on the structural state of the milled powders, two or several overlapping exothermic peaks over the temperature range 100-700 • C were revealed in the DSC scans. The saturation magnetization and coercivity values are of about 111 emu g −1 and 59 Oe, respectively, after 96 h of milling.
Journal of Alloys and Compounds, 2010
Nanocrystalline Fe75Si15B10 powders were obtained by mechanical alloying in a high energy planeta... more Nanocrystalline Fe75Si15B10 powders were obtained by mechanical alloying in a high energy planetary ball mill. Morphological, microstructural, structural and magnetic property changes during the milling process were followed by scanning electron microscopy, X-ray diffraction and magnetic measurements. The crystallite size reduction to the nanometer scale (6–13nm) is accompanied by an increase in atomic level strain. The Fe2B boride phase is
Journal of Alloys and Compounds, 2012
ABSTRACT Mechanical alloying was used to prepare Fe57Co21Nb7B15 (7Nb) and Fe61Co21Nb3B15 (3Nb) po... more ABSTRACT Mechanical alloying was used to prepare Fe57Co21Nb7B15 (7Nb) and Fe61Co21Nb3B15 (3Nb) powder mixtures in a high-energy planetary ball mill under argon atmosphere. Thermal stability, structural and magnetic properties were followed by differential scanning calorimetry, X-ray diffraction, vibrating sample magnetometry and Mössbauer spectrometry. For the Fe57Co21Nb7B15 powders, an amorphous matrix (∼69%) where nanocrystalline bcc FeCo, bcc Nb(B), tetragonal Fe2B and orthorhombic Fe3B type phases were embedded is reached after 96 h of milling. However, for the Fe61Co21Nb3B15 mixture, the partially amorphous structure (∼75%) is achieved within 48 h of milling. Further milling time (up to 96 h) gives rise to the primary crystallization of α-Fe in addition to bcc FeCo, orthorhombic FeB, tetragonal Fe2B and tetragonal Fe3B type borides. Lower Nb content powders (3Nb) exhibit higher saturation magnetization, Ms, higher coercive field, Hc, and lower glass transition temperature values than those of the 7Nb powders.
Annales de chimie Science des Matériaux, 2009
ABSTRACT
Annales de chimie Science des Matériaux, 2010
This study show that of the alloy zinc electrolytes, the chloride electrolyte influence of variou... more This study show that of the alloy zinc electrolytes, the chloride electrolyte influence of various parameters (current densities, [ nature of additive s: saccharin Na(S) and glycerol (J) … discussed. EDS Analysis was applied in Fe content with the density of current. content remains constant independently of current densities. decreases in the deposits, which is in " J.S " inhibits the electroreduction of of the three phases of the alloy Zn
In this study, the kinetics of Zn–Fe codeposition was investigated in chloride acidic solution us... more In this study, the kinetics of Zn–Fe codeposition was investigated in chloride acidic solution using cyclic voltammetry. Anomalous codeposition is detected and this mechanism depends on the Zn(II)/Fe(II) concentration ratio in the electrolytic bath. The study of early stages of electrodeposition showed that Zn-Fe follows a theoretical response to instantaneous nucleation evolves into a progressive nucleation according to the model of Scharifker and Hills. The morphology and structure of the coatings is discussed using characterization techniques. Dense, uniform, and singlephased Zn–Fe coatings could be obtained with a Zn-Fe ratio of 1/3.
This study show that of the alloy zinc-iron electrodeposited on steel by electrodeposition from c... more This study show that of the alloy zinc-iron electrodeposited on steel by electrodeposition from chloride acid electrolytes, the chloride electrolyte more advantages than the electrolyte sulphate. Furthermore the influence of various parameters(current densities, [Zn(II)]/[(Fe(II)] concentration ratio in electrolyte and the nature of additives: saccharin Na(S) and glycerol (J) …) on the morphology and the structure of the deposits is discussed. EDS Analysis making it possible to determine the composition of alloysobtained gives an increase in Fe content with the density of current.For high [Zn(II)]/[(Fe(II)]~1/9 concentration ratio in solution, Fe content remains constant independently of current densities. In the presence of brightener "J.S", the deposit contains a weaker content iron, which is in agreement with measurements of the cyclic voltammetry showing that the " J.S " inhibits the electroreduction of iron. X-ray diffractograms realized for Zn-Fe alloys, le...
ACS Nano, 2011
O ne-dimensional (1-D) nanostructures, such as silicon nanowires (SiNWs) and carbon nanotubes, ha... more O ne-dimensional (1-D) nanostructures, such as silicon nanowires (SiNWs) and carbon nanotubes, have sustained intense interest because they exhibit unique, technologically significant properties that are often substantially different from their bulk counterparts as a result of various nanoscale phenomena such as quantum confinement and enormous interfacial surface areas. In particular, recent studies of SiNWs have explored numerous effects on observable properties including orientation, 1-6 passivation, 2,7,8 diameter, 1,3,9,10 cross section (shape and aspect ratio), 1,7,11 doping, 12,13 surface-to-volume ratio, 1,11 strain, 3,4,14 and surface morphologies. 12,15 The unrealized technological potential of SiNWs is vast, especially in devices already dominated by Si materials, and includes applications such as Si process-compatible optical interconnects and waveguides in complementary metal oxide semiconductor (CMOS) integrated circuits, 16 SiNW-based solar cell arrays with enhanced broad-band optical absorption, 17,18 and efficient three-dimensional anode architectures in Li-ion battery anodes. 19 Techniques to fabricate SiNWs include both bottom-up and top-down strategies. 20 The bottom-up approach is essentially 1-D crystal synthesis involving nucleation and subsequent epitaxial growth; the most common methods are vapor-liquid-solid (VLS) and oxide-assisted growth (OAG) mechanisms. 21 VLS-grown SiNWs typically suffer from residual metal catalyst contamination, like Au or Cu, 21,22 that degrades electronic properties. OAG SiNWs can be produced by either thermal evaporation 23-26 or laser ablation 10,25 of SiO x in a growth mechanism involving phase separation into a recrystallizing Si (c-Si) core and amorphous silicon oxide (a-SiO x , 0 e x e 2) sheath that is proposed 10,25 to inhibit lateral growth. The preferred orientations of OAG SiNWs are
Computer simulation and analysis of our data compared to published results on the activation of i... more Computer simulation and analysis of our data compared to published results on the activation of impurity dopants in GaAs, have lead to the establishment of a theoretical model for the electrical properties of GaAs doped by ion implantation and annealed using rapid thermal annealing. A comparison of the behavior of different dopant species have shown that all implants in GaAs have almost the same activation mechanism except for the amphoteric Si implants where electrical activity increased normally with annealing times and temperature up to 900°C, then decreased showing that a compensating mechanisms taking place at temperature higher than 850°C. Finally the Si implanted GaAs become P type for longer annealing times at high temperatures. The purpose of our work was to establish a theoretical model capable of explaining the behavior of Si dopants in GaAs, from relationship between the annealing conditions of Si in GaAs and the electrical properties of Si implanted in GaAs.
Mechanical alloying was used to prepare the like amorphous (FeCo) 62 Nb 8 B 30 alloy from pure el... more Mechanical alloying was used to prepare the like amorphous (FeCo) 62 Nb 8 B 30 alloy from pure elemental Fe, Co, Nb and B powders. The structural and thermal properties were investigated by X-ray diffraction and differential scanning calorimetry. During the first stage of milling, it is observed the formation of metastable Fe-borides such as fcc-Fe 23 B 6 and tetragonal Fe 3 B-type phases. Calorimetric scans of the milled powder for 125 h shows one exothermic peak related to the primary nanocrystallization of the α-FeCo phase.
Nanocrystalline Fe10 %Zn and Fe30 %Zn alloys have been prepared from pure elemental powders by me... more Nanocrystalline Fe10 %Zn and Fe30 %Zn alloys have been prepared from pure elemental powders by mechanical alloying processing in a high energy planetary ball-mill. Microstructural, structural, and mag-netic characterizations of the powders were investigated by X-ray diffraction, and vibrating sample mag-nometer. The crystallite size reduction to the nanometer scale is accompanied by an increase in the atomic level strain. The reaction between Fe and Zn leads to the formation of a bcc Fe(Zn) solid solution with a lattice parameter close to (0.2912 nm for Fe30 %Zn and 0,2885 nm for Fe10 %Zn) after 5 h of milling. The complete dissolution of the elemental Zn powders in the -Fe lattice gives rise to the formation of a highly disordered Fe(Zn) solid solution, where -Fe(Zn) nanograins have a crystallite size of (229,29 Å for Fe10 %Zn (24 h) 30,09 Å for Fe30 %Zn (24 h), on prolonged milling time. The coercivity and magnetization values are 18,90 (Fe10 %Zn)Oe and 26,59 (Fe30 %Zn) emu/g, r...
International Journal of Nanoparticles, 2010
... Ratheesh Kumar, PM, Sudha Kartha, C., Vijayakumar, KP, Singh, F. and Avasthi, DK (2005) &... more ... Ratheesh Kumar, PM, Sudha Kartha, C., Vijayakumar, KP, Singh, F. and Avasthi, DK (2005) 'Effect of fluorine doping on structural, electrical and ... Rodriguez-Baez, J., Maldonado, A., Castaneda, L., Torres Delgado, G., de la Castanedo-Pérez, R. and Olvera, L. (2007) 'On the ...
Surface and Coatings Technology, 2010
Partially amorphous Fe75Si15B10 coatings were prepared from nanostructured feedstock powders by u... more Partially amorphous Fe75Si15B10 coatings were prepared from nanostructured feedstock powders by using high velocity oxy-fuel spraying. Scanning electron microscopy, X-ray diffraction, Vickers indenter and magnetic measurements were used to investigate microstructural, structural, microhardness and magnetic properties of the coatings. The Rietveld refinement of the X-ray diffraction patterns reveals the presence of an amorphous phase, nanocrystalline α-Fe(Si,B) structure having a lattice
International Journal of Nanoparticles, 2011
Fe 61 Co 21 Nb 3 B 15 powder mixture was prepared by mechanical alloying process in a high energy... more Fe 61 Co 21 Nb 3 B 15 powder mixture was prepared by mechanical alloying process in a high energy planetary ball mill. Structural and thermal changes of the milled powders were followed by X-ray diffraction (XRD), Mössbauer spectrometry and differential scanning calorimetry (DSC). Both XRD and Mössbauer spectrometry results reveal the formation, after 48 h of milling, of a highly disordered amorphous-like structure where nanometer-sized iron borides were embedded. A mechanical recrystallisation process gives rise to the formation of α-Fe and α-FeCo nanograins on further milling. The occurrence of structural disorder in the milled powders might be confirmed by broad exothermic reaction in the DSC scans which consists of several overlapping exothermic peaks. Such behaviour originates from recovery, strain relaxation, grain growth and crystallisation.
ABSTRACT X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investi... more ABSTRACT X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate the phase identification and the thermal behaviour of the mechanically alloyed Fe57Co21Nb7B15 powders. The diffusion of B into the Nb lattice leads, after 1 h of milling, to the formation of a bcc Nb(B) solid solution with a lattice parameter close to a = 0.3425 nm. The solid state reaction between Fe and B gives rise to the formation of Fe23B6 and Fe2B boride phases after 3 and 6 h of milling, respectively. On further milling (96 h), an amorphous matrix (~80%), where nanocrystalline bcc α-Fe, bcc Nb(B), Fe2B and Fe3B phases were embedded, is obtained. The broad exothermic reaction in the DSC scans consists of several exothermic peaks and spreads over the entire temperature range 100–700°C. The enthalpy release at temperatures below 300°C can be attributed to recovery and strain relaxation. Crystallisation and grain growth are the dominating processes at high temperatures.
Energy Procedia, 2013
Equation of state (EOS) and other thermodynamic properties of Fe 2 B are studied using first-prin... more Equation of state (EOS) and other thermodynamic properties of Fe 2 B are studied using first-principles calculations based on the plane wave full potential density functional theory method within the generalized gradient approximation (GGA) for exchange and correlation. It is demonstrated that the ratio c/a of about 1.271 is the most stable structure for the Fe 2 B, which is consistent with the experimental data. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of the relative volume V/V 0 on pressure P, cell volume V, and on temperature T, are successfully obtained. The variations of the Debye temperature (V), the thermal expansion , and the heat capacity C V as a function of pressure P and temperature T, are investigated systematically in the ranges of 0-50 GPa and 0-1000 K.
International Journal of Nanoparticles, 2010
Elemental Fe and red phosphorus powders with a composition close to Fe-xP (x = 10, 15 and 20 wt. ... more Elemental Fe and red phosphorus powders with a composition close to Fe-xP (x = 10, 15 and 20 wt. %) were mechanically alloyed in a planetary ball mill under an argon atmosphere. Structural changes were studied by X-ray diffraction. The complete dissolution of the elemental powders is achieved within 3 h of milling. Detailed analysis of the X-ray diffraction patterns reveal the formation of a Fe(P) solid solution with two structures (α-Fe1 and α-Fe2) having different lattice parameters, crystallite size and microstrains in addition to FeP, Fe 2 P and Fe 3 P phosphides. The structural parameters and phase percentages are P content dependent.
physica status solidi (a), 2008
1 Laboratoire de Magnétisme et de Spectroscopie des Solides, Département de Physique, Faculté des... more 1 Laboratoire de Magnétisme et de Spectroscopie des Solides, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, 23000 Annaba, Algeria 2 CNRS-Laboratoire de Chimie Métallurgique des Terres Rares-Groupe des Laboratoires de Thiais, 28 Rue ...
Materials Chemistry and Physics, 2010
Mössbauer spectrometry and Rietveld analysis of X-ray diffraction patterns were used to follow th... more Mössbauer spectrometry and Rietveld analysis of X-ray diffraction patterns were used to follow the solid state amorphization transformation during the milling process of the Fe27.9Nb2.2B69.9 powders. The reaction between elemental Fe, Nb and B powders leads to the formation of the Nb(B) and Fe(B) solid solutions after 1 and 10h of milling, respectively. A mixture of α-Fe, Nb(B) and highly
Materials Chemistry and Physics, 2012
Partially amorphous Fe 57 Co 21 Nb 7 B 15 powder mixture was prepared by mechanical alloying in a... more Partially amorphous Fe 57 Co 21 Nb 7 B 15 powder mixture was prepared by mechanical alloying in a high energy planetary ball-mill under argon atmosphere. Thermal stability, magnetic properties, structural and morphological changes during the milling process were followed by differential scanning calorimetry, vibrating sample magnetometry, X-ray diffraction and scanning electron microscopy. A duplex nanostructure of Fe(Co) and Fe-boride nanocrystals within an amorphous matrix is achieved on further milling time. Depending on the structural state of the milled powders, two or several overlapping exothermic peaks over the temperature range 100-700 • C were revealed in the DSC scans. The saturation magnetization and coercivity values are of about 111 emu g −1 and 59 Oe, respectively, after 96 h of milling.
Journal of Alloys and Compounds, 2010
Nanocrystalline Fe75Si15B10 powders were obtained by mechanical alloying in a high energy planeta... more Nanocrystalline Fe75Si15B10 powders were obtained by mechanical alloying in a high energy planetary ball mill. Morphological, microstructural, structural and magnetic property changes during the milling process were followed by scanning electron microscopy, X-ray diffraction and magnetic measurements. The crystallite size reduction to the nanometer scale (6–13nm) is accompanied by an increase in atomic level strain. The Fe2B boride phase is
Journal of Alloys and Compounds, 2012
ABSTRACT Mechanical alloying was used to prepare Fe57Co21Nb7B15 (7Nb) and Fe61Co21Nb3B15 (3Nb) po... more ABSTRACT Mechanical alloying was used to prepare Fe57Co21Nb7B15 (7Nb) and Fe61Co21Nb3B15 (3Nb) powder mixtures in a high-energy planetary ball mill under argon atmosphere. Thermal stability, structural and magnetic properties were followed by differential scanning calorimetry, X-ray diffraction, vibrating sample magnetometry and Mössbauer spectrometry. For the Fe57Co21Nb7B15 powders, an amorphous matrix (∼69%) where nanocrystalline bcc FeCo, bcc Nb(B), tetragonal Fe2B and orthorhombic Fe3B type phases were embedded is reached after 96 h of milling. However, for the Fe61Co21Nb3B15 mixture, the partially amorphous structure (∼75%) is achieved within 48 h of milling. Further milling time (up to 96 h) gives rise to the primary crystallization of α-Fe in addition to bcc FeCo, orthorhombic FeB, tetragonal Fe2B and tetragonal Fe3B type borides. Lower Nb content powders (3Nb) exhibit higher saturation magnetization, Ms, higher coercive field, Hc, and lower glass transition temperature values than those of the 7Nb powders.
Annales de chimie Science des Matériaux, 2009
ABSTRACT
Annales de chimie Science des Matériaux, 2010
This study show that of the alloy zinc electrolytes, the chloride electrolyte influence of variou... more This study show that of the alloy zinc electrolytes, the chloride electrolyte influence of various parameters (current densities, [ nature of additive s: saccharin Na(S) and glycerol (J) … discussed. EDS Analysis was applied in Fe content with the density of current. content remains constant independently of current densities. decreases in the deposits, which is in " J.S " inhibits the electroreduction of of the three phases of the alloy Zn
In this study, the kinetics of Zn–Fe codeposition was investigated in chloride acidic solution us... more In this study, the kinetics of Zn–Fe codeposition was investigated in chloride acidic solution using cyclic voltammetry. Anomalous codeposition is detected and this mechanism depends on the Zn(II)/Fe(II) concentration ratio in the electrolytic bath. The study of early stages of electrodeposition showed that Zn-Fe follows a theoretical response to instantaneous nucleation evolves into a progressive nucleation according to the model of Scharifker and Hills. The morphology and structure of the coatings is discussed using characterization techniques. Dense, uniform, and singlephased Zn–Fe coatings could be obtained with a Zn-Fe ratio of 1/3.
This study show that of the alloy zinc-iron electrodeposited on steel by electrodeposition from c... more This study show that of the alloy zinc-iron electrodeposited on steel by electrodeposition from chloride acid electrolytes, the chloride electrolyte more advantages than the electrolyte sulphate. Furthermore the influence of various parameters(current densities, [Zn(II)]/[(Fe(II)] concentration ratio in electrolyte and the nature of additives: saccharin Na(S) and glycerol (J) …) on the morphology and the structure of the deposits is discussed. EDS Analysis making it possible to determine the composition of alloysobtained gives an increase in Fe content with the density of current.For high [Zn(II)]/[(Fe(II)]~1/9 concentration ratio in solution, Fe content remains constant independently of current densities. In the presence of brightener "J.S", the deposit contains a weaker content iron, which is in agreement with measurements of the cyclic voltammetry showing that the " J.S " inhibits the electroreduction of iron. X-ray diffractograms realized for Zn-Fe alloys, le...
ACS Nano, 2011
O ne-dimensional (1-D) nanostructures, such as silicon nanowires (SiNWs) and carbon nanotubes, ha... more O ne-dimensional (1-D) nanostructures, such as silicon nanowires (SiNWs) and carbon nanotubes, have sustained intense interest because they exhibit unique, technologically significant properties that are often substantially different from their bulk counterparts as a result of various nanoscale phenomena such as quantum confinement and enormous interfacial surface areas. In particular, recent studies of SiNWs have explored numerous effects on observable properties including orientation, 1-6 passivation, 2,7,8 diameter, 1,3,9,10 cross section (shape and aspect ratio), 1,7,11 doping, 12,13 surface-to-volume ratio, 1,11 strain, 3,4,14 and surface morphologies. 12,15 The unrealized technological potential of SiNWs is vast, especially in devices already dominated by Si materials, and includes applications such as Si process-compatible optical interconnects and waveguides in complementary metal oxide semiconductor (CMOS) integrated circuits, 16 SiNW-based solar cell arrays with enhanced broad-band optical absorption, 17,18 and efficient three-dimensional anode architectures in Li-ion battery anodes. 19 Techniques to fabricate SiNWs include both bottom-up and top-down strategies. 20 The bottom-up approach is essentially 1-D crystal synthesis involving nucleation and subsequent epitaxial growth; the most common methods are vapor-liquid-solid (VLS) and oxide-assisted growth (OAG) mechanisms. 21 VLS-grown SiNWs typically suffer from residual metal catalyst contamination, like Au or Cu, 21,22 that degrades electronic properties. OAG SiNWs can be produced by either thermal evaporation 23-26 or laser ablation 10,25 of SiO x in a growth mechanism involving phase separation into a recrystallizing Si (c-Si) core and amorphous silicon oxide (a-SiO x , 0 e x e 2) sheath that is proposed 10,25 to inhibit lateral growth. The preferred orientations of OAG SiNWs are
Computer simulation and analysis of our data compared to published results on the activation of i... more Computer simulation and analysis of our data compared to published results on the activation of impurity dopants in GaAs, have lead to the establishment of a theoretical model for the electrical properties of GaAs doped by ion implantation and annealed using rapid thermal annealing. A comparison of the behavior of different dopant species have shown that all implants in GaAs have almost the same activation mechanism except for the amphoteric Si implants where electrical activity increased normally with annealing times and temperature up to 900°C, then decreased showing that a compensating mechanisms taking place at temperature higher than 850°C. Finally the Si implanted GaAs become P type for longer annealing times at high temperatures. The purpose of our work was to establish a theoretical model capable of explaining the behavior of Si dopants in GaAs, from relationship between the annealing conditions of Si in GaAs and the electrical properties of Si implanted in GaAs.