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Papers by jesus anselmo tabares giraldo
IP 1106-05-061-96Incluye anexos.v.1. Estudio del comportamiento mecanico, magnetico y a lacorrosi... more IP 1106-05-061-96Incluye anexos.v.1. Estudio del comportamiento mecanico, magnetico y a lacorrosion de aleaciones Fe-Mn-Al fundidas, sitetizadas y mecanicamente aleadas / German Antonio PerezAlcazar -- v.2.Resumen de 11 tesis sustentadas durante el proyecto.ARTICULO(S) EN REVISTA: Proceeding of LACAME`98 : sixth LatinAmerican Conference on applications of the;Mossebauer effect / Jesus A. Tabares, Alberto Bohorquez G,LigiaE. Zamora, German A. Perez Alcazar. -- En:;Hyperfine Interactions. -- Vol. 4 (nov. 1999); 150 p. --Applications ofthe Mossbauer effect (LACAME'98):;proceedings of the 6th Latin American Conference on applicationsof Mossbauer effect / Jesus A. Tabares,;Alberto Bohorquez, Ligia E. Zamora, German A. Perez Alcazar. --En: Hyperfine Interactions : journal devoted;to research in the borders regions of solid state, atomicandnuclear physics. -- Vol. 122, no. 1,2 (nov.;1999); 222 p. -- CURSO: Pricipios basicos instrumentaciony aplicaciones :suelos, carbones, metalurgia,;magnetismo, estudio de superficies. / German A. Perez Alcazar,Alexander Osorio Caicedo, Monica Maria Rico;Castro. -- En: 2o curso sobre espectroscopia Mossbauer. --(1996, sep 27-23 : Cali). -- Cali : Universidad del;Valle, 1996. -- 28 cm. ; 66 p
Applied Physics A, 2020
In the present work, the structural, magnetic, and theoretical analysis of the Fe-Si alloy prepar... more In the present work, the structural, magnetic, and theoretical analysis of the Fe-Si alloy prepared by melting and heattreated was performed. The ordered FeSi simple cubic (sc) phase was obtained by melting and heat treatment processes as determined by X-ray diffraction. The presence of the superstructure peak in the (312) crystalline direction confirms the high structural order reached. Using Mössbauer spectrometry (MS), a paramagnetic behavior with quadrupole splitting of SQ = 0.53 ± 0.02 mm/s was obtained. Although MS indicates paramagnetic behavior, vibrating sample magnetometry (VSM) showed ferromagnetic behavior with a coercive field of 25 Oe, associated with a small amount of Fe3Si segregations detected by scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). Using density functional theory (DFT), the crystalline structures for the simple cubic (sc) Fe 50 Si 50 , face-centered cubic (fcc) Fe 3 Si, and body-centered cubic (bcc) Fe 3 Si crystalline structures were simulated. Electron total density values were calculated to perform energetic comparisons with magnetic behavior. The electronic structures and magnetic properties of the Fe-Si alloys in different stoichiometric configurations were calculated by CASTEP, which employed first principles DFT. The density of states (DOS) and band structures were calculated together with magnetic properties. The results showed that the high value of the polarization spin for the fcc and bcc structures is due to the contribution of the high amount of Fe atoms above the Si atoms, which is reflected in an increase in the magnetic moment and that their presence could explain the ferromagnetic behavior observed by VSM.
Hyperfine Interactions, 2017
We report on the synthesis of Bi 0.4 Sr 0.6 FeO 3 powder with cubic structure by solid state reac... more We report on the synthesis of Bi 0.4 Sr 0.6 FeO 3 powder with cubic structure by solid state reaction (mechanical milling and calcination) from Bi 2 O 3 , SrCO 3 and Fe 2 O 3 stoichiometric ratios. Milled powder mixtures were heat treated between 775 • C and 825 • C for 30 and 60 min in oxygen atmosphere and characterized by X-ray diffraction (XRD), impedance as well as Mössbauer spectroscopy. The cubic phase of Bi 0.4 Sr 0.6 FeO 3 was successfully obtained in samples milled for only 2 h and a subsequent calcination at 800 • C. Irrespective of milling time, heat treatments at lower temperatures (775 • C) still show spurious phases such as Sr 0.23 Bi 0.76 O 1.1 (30 min) and Sr 0.53 Bi 1.72 O 3 (60 min). Impedance spectroscopy This article is part of the Topical Collection on
The fundamentals of Mössbauer Spectroscopy in the backscattering mode are given. The techniques u... more The fundamentals of Mössbauer Spectroscopy in the backscattering mode are given. The techniques used for the different backscattered particles and energies, and the experimental difficulties and advantages of each technique are discussed.
Two methods are used that allow to linearly correlating the mass of soil with information origi- ... more Two methods are used that allow to linearly correlating the mass of soil with information origi- nated from the natural gamma radiation spectrum. The first method consists in adding the counts in a region of interest (ROI) of the original spectrum and correlating them with the mass of the sample. The second method uses the Continuous Wavelet Transformed and allows correlating co- efficients wavelet with the mass of the sample. Due that for industrial applications low times of measurement are required, then the change of the coefficient of linear correlation as a function of the time required for each spectrum is studied. For a shilding wide of 6 cm and a measured time of 5 minutes, the coefficient of linear correlation is stabilized to an acceptable value for both meth- ods.
Journal of Magnetism and Magnetic Materials, 2013
Se realizó la caracterización estructural, magnética y calorimétrica por medio de Difracción de R... more Se realizó la caracterización estructural, magnética y calorimétrica por medio de Difracción de Rayos-X (DRX), Microscopia Electrónica de Barrido (SEM), Calorimetría Diferencial de Barrido (DSC), Espectrometría Mössbauer (EM), y Magnetometría de Muestra Vibrante (VSM), de los sistemas Mn54.3Al44C1.7, Mn54.3Al44C1.7/Fe, y Mn(53.3-x)Al45C1.7Tix, con x = 0.0, 0.5, 1.0, 1.5 % atómico de Ti. Las muestras se prepararon mediante fundición en horno de arco 4 veces para garantizar la homogenización de las muestras y posteriormente se realizó melt-spinnnig a diferentes velocidades (10, 20, 30, 40 y 50 m/s) a una presión de 400/450 mbar. Los patrones de difracción de rayos X nos permiten identificar que tanto el contenido de carbono como el dopaje con Ti ayuda a estabilizar la fase (¿) después de hacer melt-spinning y la fase ¿ después de hacer tratamiento térmico entre 500-550oC. Adicionalmente, debido a que la fase ¿ es metaestable, para tratamientos entre 450-500oC, aparecen fases minoritarias como la fase ¿-Mn y la fase ¿2-Mn, las cuales son paramagnéticas. Además, se encontró que el parámetro de red a y c y el volumen de la celda unitaria no presentan alguna tendencia general a cambiar con la concentración de titanio
Journal of Superconductivity and Novel Magnetism
The natural-gamma nuclear technique is applied to determine the quantity of mineral matter com- i... more The natural-gamma nuclear technique is applied to determine the quantity of mineral matter com- ing from the soil that accompanies the cuts of cane of sugar in samples simulated in the laboratory. An assembly was made and used to measure in the laboratory. The calibration was made preparing samples with known cane content and soil, measuring the respective natural gamma
We report on the magnetic properties of Fex Mn0.3 Al0.7-x (0.275
Journal of Physics: Conference Series, 2015
In this work, we studied the catalytic activity, structural properties, and behavior of a Fe 3 O ... more In this work, we studied the catalytic activity, structural properties, and behavior of a Fe 3 O 4 magnetic system. The Fe 3 O 4 nanoparticles were prepared by the thermal decomposition method. X-ray diffraction confirmed the presence of a structural Fe 3 O 4 phase, where acicular shape of the grains is shown. Transmission Mössbauer spectroscopy showed a wide distribution of particle sizes at room temperature, some of these present superparamagnetic behavior and are responsible of paramagnetic sites. The hysteresis loops obtained by the use of a vibrating sample magnetometer showed that these nanoparticles exhibit superparamagnetic behavior. However, the cycles present a significant contribution from a ferrimagnetic component at 2 K, which agrees with Mössbauer results. Through scanning electron microscopy, a tendency to the agglomeration of nanoparticles was observed. Nanoparticle activity in the degradation of methylene blue (MB) was studied through fluorescence spectroscopy, finding dye adsorption properties.
Hyperfine Interactions, 2015
ABSTRACT The structural and magnetic properties of Fe-doped ZnO are reported in this study, as ob... more ABSTRACT The structural and magnetic properties of Fe-doped ZnO are reported in this study, as obtained by mechanical alloying from elemental powders of ZnO and Fe. The properties of Zn 0.90 Fe 0.10 O samples alloying while varying the milling time (6, 12, 24 and 36 h) are also reported. The Rietveld refinement of X-ray Diffraction (XRD) patterns revealed that the system presents two structures: the würtzite structure of ZnO and the bcc structure of α-Fe. The Mössbauer spectra show that the samples present three components: a ferromagnetic component, associated with the Fe phase and two paramagnetic components, associated with the Fe atoms, which penetrate inside the ZnO matrix behaving as Fe 3+ and Fe 2+. The milling time contributes to an increase in the paramagnetic sites, and a solubility limit of the Fe atoms in the ZnO lattice was detected. The VSM measurements at room temperature detected ferromagnetic behavior with a saturation magnetization of 11 emu/g and a coercive field of 330 Oe for the sample alloyed over 24 h. A similar behavior was shown by the other samples.
Materials Science Forum, 1999
Il Nuovo Cimento D, 1996
Summary The characterization of the corrosion products formed on an 57 Fe film onto a low alloy s... more Summary The characterization of the corrosion products formed on an 57 Fe film onto a low alloy steel disc after 4 h and 8 h exposure to an artificially SO 2-polluted atmosphere has been carried out by ICEMS/DCEMS. The corrosion products found are FeSO 3· 3H 2 O, ...
Materials Science Forum, 1999
ABSTRACT
Revista de la …, 2005
La materia mineral presente en el carbón es obtenida en la actualidad por el método denominado ce... more La materia mineral presente en el carbón es obtenida en la actualidad por el método denominado cenizado a alta temperatura (CAT), el cual consiste en la combustión controlada de una muestra representativa de carbón (1 gr. de masa) a 750ºC, eliminando su parte orgánica y condensando su parte mineral. Este método está caracterizado por ser un proceso de caracterización puntual. En busca de un método más eficaz para la caracterización del contenido de ceniza del carbón, se ha implementado la técnica nuclear neutrón-gama (n-γ), la cual consiste en la incidencia sobre el carbón natural de neutrones emitidos por una fuente radiactiva (252 Cf), los cuales al ser absorbidos por los elementos constituyentes del carbón, éstos reaccionan emitiendo una radiación característica de gamas inmediatos, suministrando información sobre la materia mineral presente en el carbón en su estado natural y sobre un volumen más representativo de aproximadamente 40 cm. de radio.
IP 1106-05-061-96Incluye anexos.v.1. Estudio del comportamiento mecanico, magnetico y a lacorrosi... more IP 1106-05-061-96Incluye anexos.v.1. Estudio del comportamiento mecanico, magnetico y a lacorrosion de aleaciones Fe-Mn-Al fundidas, sitetizadas y mecanicamente aleadas / German Antonio PerezAlcazar -- v.2.Resumen de 11 tesis sustentadas durante el proyecto.ARTICULO(S) EN REVISTA: Proceeding of LACAME`98 : sixth LatinAmerican Conference on applications of the;Mossebauer effect / Jesus A. Tabares, Alberto Bohorquez G,LigiaE. Zamora, German A. Perez Alcazar. -- En:;Hyperfine Interactions. -- Vol. 4 (nov. 1999); 150 p. --Applications ofthe Mossbauer effect (LACAME'98):;proceedings of the 6th Latin American Conference on applicationsof Mossbauer effect / Jesus A. Tabares,;Alberto Bohorquez, Ligia E. Zamora, German A. Perez Alcazar. --En: Hyperfine Interactions : journal devoted;to research in the borders regions of solid state, atomicandnuclear physics. -- Vol. 122, no. 1,2 (nov.;1999); 222 p. -- CURSO: Pricipios basicos instrumentaciony aplicaciones :suelos, carbones, metalurgia,;magnetismo, estudio de superficies. / German A. Perez Alcazar,Alexander Osorio Caicedo, Monica Maria Rico;Castro. -- En: 2o curso sobre espectroscopia Mossbauer. --(1996, sep 27-23 : Cali). -- Cali : Universidad del;Valle, 1996. -- 28 cm. ; 66 p
Applied Physics A, 2020
In the present work, the structural, magnetic, and theoretical analysis of the Fe-Si alloy prepar... more In the present work, the structural, magnetic, and theoretical analysis of the Fe-Si alloy prepared by melting and heattreated was performed. The ordered FeSi simple cubic (sc) phase was obtained by melting and heat treatment processes as determined by X-ray diffraction. The presence of the superstructure peak in the (312) crystalline direction confirms the high structural order reached. Using Mössbauer spectrometry (MS), a paramagnetic behavior with quadrupole splitting of SQ = 0.53 ± 0.02 mm/s was obtained. Although MS indicates paramagnetic behavior, vibrating sample magnetometry (VSM) showed ferromagnetic behavior with a coercive field of 25 Oe, associated with a small amount of Fe3Si segregations detected by scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). Using density functional theory (DFT), the crystalline structures for the simple cubic (sc) Fe 50 Si 50 , face-centered cubic (fcc) Fe 3 Si, and body-centered cubic (bcc) Fe 3 Si crystalline structures were simulated. Electron total density values were calculated to perform energetic comparisons with magnetic behavior. The electronic structures and magnetic properties of the Fe-Si alloys in different stoichiometric configurations were calculated by CASTEP, which employed first principles DFT. The density of states (DOS) and band structures were calculated together with magnetic properties. The results showed that the high value of the polarization spin for the fcc and bcc structures is due to the contribution of the high amount of Fe atoms above the Si atoms, which is reflected in an increase in the magnetic moment and that their presence could explain the ferromagnetic behavior observed by VSM.
Hyperfine Interactions, 2017
We report on the synthesis of Bi 0.4 Sr 0.6 FeO 3 powder with cubic structure by solid state reac... more We report on the synthesis of Bi 0.4 Sr 0.6 FeO 3 powder with cubic structure by solid state reaction (mechanical milling and calcination) from Bi 2 O 3 , SrCO 3 and Fe 2 O 3 stoichiometric ratios. Milled powder mixtures were heat treated between 775 • C and 825 • C for 30 and 60 min in oxygen atmosphere and characterized by X-ray diffraction (XRD), impedance as well as Mössbauer spectroscopy. The cubic phase of Bi 0.4 Sr 0.6 FeO 3 was successfully obtained in samples milled for only 2 h and a subsequent calcination at 800 • C. Irrespective of milling time, heat treatments at lower temperatures (775 • C) still show spurious phases such as Sr 0.23 Bi 0.76 O 1.1 (30 min) and Sr 0.53 Bi 1.72 O 3 (60 min). Impedance spectroscopy This article is part of the Topical Collection on
The fundamentals of Mössbauer Spectroscopy in the backscattering mode are given. The techniques u... more The fundamentals of Mössbauer Spectroscopy in the backscattering mode are given. The techniques used for the different backscattered particles and energies, and the experimental difficulties and advantages of each technique are discussed.
Two methods are used that allow to linearly correlating the mass of soil with information origi- ... more Two methods are used that allow to linearly correlating the mass of soil with information origi- nated from the natural gamma radiation spectrum. The first method consists in adding the counts in a region of interest (ROI) of the original spectrum and correlating them with the mass of the sample. The second method uses the Continuous Wavelet Transformed and allows correlating co- efficients wavelet with the mass of the sample. Due that for industrial applications low times of measurement are required, then the change of the coefficient of linear correlation as a function of the time required for each spectrum is studied. For a shilding wide of 6 cm and a measured time of 5 minutes, the coefficient of linear correlation is stabilized to an acceptable value for both meth- ods.
Journal of Magnetism and Magnetic Materials, 2013
Se realizó la caracterización estructural, magnética y calorimétrica por medio de Difracción de R... more Se realizó la caracterización estructural, magnética y calorimétrica por medio de Difracción de Rayos-X (DRX), Microscopia Electrónica de Barrido (SEM), Calorimetría Diferencial de Barrido (DSC), Espectrometría Mössbauer (EM), y Magnetometría de Muestra Vibrante (VSM), de los sistemas Mn54.3Al44C1.7, Mn54.3Al44C1.7/Fe, y Mn(53.3-x)Al45C1.7Tix, con x = 0.0, 0.5, 1.0, 1.5 % atómico de Ti. Las muestras se prepararon mediante fundición en horno de arco 4 veces para garantizar la homogenización de las muestras y posteriormente se realizó melt-spinnnig a diferentes velocidades (10, 20, 30, 40 y 50 m/s) a una presión de 400/450 mbar. Los patrones de difracción de rayos X nos permiten identificar que tanto el contenido de carbono como el dopaje con Ti ayuda a estabilizar la fase (¿) después de hacer melt-spinning y la fase ¿ después de hacer tratamiento térmico entre 500-550oC. Adicionalmente, debido a que la fase ¿ es metaestable, para tratamientos entre 450-500oC, aparecen fases minoritarias como la fase ¿-Mn y la fase ¿2-Mn, las cuales son paramagnéticas. Además, se encontró que el parámetro de red a y c y el volumen de la celda unitaria no presentan alguna tendencia general a cambiar con la concentración de titanio
Journal of Superconductivity and Novel Magnetism
The natural-gamma nuclear technique is applied to determine the quantity of mineral matter com- i... more The natural-gamma nuclear technique is applied to determine the quantity of mineral matter com- ing from the soil that accompanies the cuts of cane of sugar in samples simulated in the laboratory. An assembly was made and used to measure in the laboratory. The calibration was made preparing samples with known cane content and soil, measuring the respective natural gamma
We report on the magnetic properties of Fex Mn0.3 Al0.7-x (0.275
Journal of Physics: Conference Series, 2015
In this work, we studied the catalytic activity, structural properties, and behavior of a Fe 3 O ... more In this work, we studied the catalytic activity, structural properties, and behavior of a Fe 3 O 4 magnetic system. The Fe 3 O 4 nanoparticles were prepared by the thermal decomposition method. X-ray diffraction confirmed the presence of a structural Fe 3 O 4 phase, where acicular shape of the grains is shown. Transmission Mössbauer spectroscopy showed a wide distribution of particle sizes at room temperature, some of these present superparamagnetic behavior and are responsible of paramagnetic sites. The hysteresis loops obtained by the use of a vibrating sample magnetometer showed that these nanoparticles exhibit superparamagnetic behavior. However, the cycles present a significant contribution from a ferrimagnetic component at 2 K, which agrees with Mössbauer results. Through scanning electron microscopy, a tendency to the agglomeration of nanoparticles was observed. Nanoparticle activity in the degradation of methylene blue (MB) was studied through fluorescence spectroscopy, finding dye adsorption properties.
Hyperfine Interactions, 2015
ABSTRACT The structural and magnetic properties of Fe-doped ZnO are reported in this study, as ob... more ABSTRACT The structural and magnetic properties of Fe-doped ZnO are reported in this study, as obtained by mechanical alloying from elemental powders of ZnO and Fe. The properties of Zn 0.90 Fe 0.10 O samples alloying while varying the milling time (6, 12, 24 and 36 h) are also reported. The Rietveld refinement of X-ray Diffraction (XRD) patterns revealed that the system presents two structures: the würtzite structure of ZnO and the bcc structure of α-Fe. The Mössbauer spectra show that the samples present three components: a ferromagnetic component, associated with the Fe phase and two paramagnetic components, associated with the Fe atoms, which penetrate inside the ZnO matrix behaving as Fe 3+ and Fe 2+. The milling time contributes to an increase in the paramagnetic sites, and a solubility limit of the Fe atoms in the ZnO lattice was detected. The VSM measurements at room temperature detected ferromagnetic behavior with a saturation magnetization of 11 emu/g and a coercive field of 330 Oe for the sample alloyed over 24 h. A similar behavior was shown by the other samples.
Materials Science Forum, 1999
Il Nuovo Cimento D, 1996
Summary The characterization of the corrosion products formed on an 57 Fe film onto a low alloy s... more Summary The characterization of the corrosion products formed on an 57 Fe film onto a low alloy steel disc after 4 h and 8 h exposure to an artificially SO 2-polluted atmosphere has been carried out by ICEMS/DCEMS. The corrosion products found are FeSO 3· 3H 2 O, ...
Materials Science Forum, 1999
ABSTRACT
Revista de la …, 2005
La materia mineral presente en el carbón es obtenida en la actualidad por el método denominado ce... more La materia mineral presente en el carbón es obtenida en la actualidad por el método denominado cenizado a alta temperatura (CAT), el cual consiste en la combustión controlada de una muestra representativa de carbón (1 gr. de masa) a 750ºC, eliminando su parte orgánica y condensando su parte mineral. Este método está caracterizado por ser un proceso de caracterización puntual. En busca de un método más eficaz para la caracterización del contenido de ceniza del carbón, se ha implementado la técnica nuclear neutrón-gama (n-γ), la cual consiste en la incidencia sobre el carbón natural de neutrones emitidos por una fuente radiactiva (252 Cf), los cuales al ser absorbidos por los elementos constituyentes del carbón, éstos reaccionan emitiendo una radiación característica de gamas inmediatos, suministrando información sobre la materia mineral presente en el carbón en su estado natural y sobre un volumen más representativo de aproximadamente 40 cm. de radio.