Papers Vol. 7 núm. 14 julio-diciembre 2011 by J.E. Alfonso
"En este trabajo se prepararon películas delgadas de trióxido de molibdeno (MoO3) por la técnica ... more "En este trabajo se prepararon películas delgadas de trióxido de molibdeno (MoO3) por la técnica de atomización pirolítica. Las películas fueron depositadas sobre sustratos de vidrio y obtenidas a partir de una solución precursora de Heptamolibdato de Amonio Tetrahidratado ((NH3) 6Mo7O24.4H2O) 0.1 M. La temperatura del sustrato se mantuvo constante en 400 oC y se varió el volumen de la solución precursora. Las muestras se caracterizaron por difracción de Rayos X (XRD), espectroscopía infrarroja, Microscopía Electrónica de Barrido (SEM) y eléctricamente a través de medidas de resistividad eléctrica en función de la temperatura. Las muestras crecen con estructura cristalina correspondiente a la fase alfa del MoO3 con dirección preferencial de crecimiento a lo largo de los planos (0k0). Al aumentar el volumen de la solución precursora la superficie de las muestras se vuelve porosa. La resistividad en estas muestras cambia en un orden de magnitud cuando son expuestas a la atmosfera de CO"
Papers by J.E. Alfonso
Surface and Coatings Technology, 2014
In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating techniq... more In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating technique, by depoited four layers of mixtuer solution contians Cadmium acetate dehydrate, Triethylamine, glycerol and ethanol.The spin coated solution were dried at 100°C and annealied at (300,350 and 400 o C temperatures ). The x-ray diffraction techniques and UV-VIS spectrophotometer have confirmed the structural and the optical properties the prepared thin films. CdO thin films were found to have polycrystalline nature with cubic rock salt phase. The crystallinity being improved, the FWHM decreases and the grain size of the CdO thin films increased with increasing the annealing temperatures. The average grain size is observed in the range (23.97 -30.47) nm which indicate that the prepared film have a nanocrystalline structure. From optical analysis, it can be seen that there are an increases in the absorbance and decreases in the trancemittance of the prepared films with the increasing of the annealing temperatures.The optical band gap decreases from 2.556, to 2.081 eV with increasing of annealing temperature fromm 300 to 400° C, this suggested that the optical band gap for CdO nanocrystalline thin films is strongly dependent on the annealing temperature.
In this work we report on the results obtained on NbN x thin films grown on both common glass and... more In this work we report on the results obtained on NbN x thin films grown on both common glass and silicon wafer substrates by RF magnetron sputtering at different substrate temperatures and different target power supplies. The crystalinity, morphology and surface composition of the deposited films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively.
ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their ele... more ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation BixTiyOz thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti6Al4V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi3+ and Ti4+.
This paper reports the influence of substrate temperature on the structure, morphology and corros... more This paper reports the influence of substrate temperature on the structure, morphology and corrosion resistance of ZrO x N y /ZrO 2 thin films deposited on 304 stainless steel using radio frequency sputtering (RF sputtering). Structural analysis was carried out by X-ray diffraction (XRD); morphological analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and surface chemical analysis was determined using X-ray photoelectron spectroscopy (XPS). XRD data showed that the films deposited at 300 • C (573 K) and 350 • C (623 K) result in the growth of a monoclinic zirconium oxynitride phase with preferential orientation along the (−1 1 1) plane, while at 14 • C (287 K) the predominant phase is of polycrystalline ZrO 2 . The corrosion results indicate that the coatings provide good resistance to corrosion in chloride-containing media, being better in the film deposited at 350 • C (623 K). SEM analysis demonstrated the homogeneity of the films deposited at the three temperatures; AFM studies established the average roughness of the films to be 4.25 nm. The binding energies of the Zr 3d, N 1s, and O 1s core levels determined by XPS were all compatible with the formation of a zirconium oxynitride and zirconium oxide in the surface of the film. ZrO x N y /ZrO 2 thin films are promising candidates for increasing the corrosion resistance of the steels in chloride-rich environments.
Ceramics International, 2014
Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering techn... more Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering technique on (100) silicon substrates. In the process, annealing was performed in both oxygen and dry air atmospheres at 600 1C for 30 and 120 min. The structure of the thin films was characterized through X-ray diffraction (XRD), and the ferroelectric response was determined with measurements of piezoelectric force microscopy (PFM). Bi 4 Ti 3 O 12 with a predominant orthorhombic phase was obtained in the annealed thin films. All the annealed films exhibited the characteristic hysteresis and butterfly loops of ferroelectric materials. Thermal annealing of Bi x Ti y O z films in an atmosphere of air for 30 min resulted in the highest d 33 value of 78 7 14 pm/V, which decreased to 64 7 26 pm/V for 120 min. On the other hand, annealing in an oxygen atmosphere produced Bi x Ti y O z films with more uniform d 33 values, 54 7 3 pm/V and 427 6 pm/V for 30 and 120 min, respectively. Ferroelectric coefficient values decreased with the increase of annealing time in an oxidant atmosphere, which can be explained by the vacancies present. These results are consistent with the experimental measurements carried out in other investigations.
Surface and Coatings Technology, 2014
In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating techniq... more In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating technique, by depoited four layers of mixtuer solution contians Cadmium acetate dehydrate, Triethylamine, glycerol and ethanol.The spin coated solution were dried at 100°C and annealied at (300,350 and 400 o C temperatures ). The x-ray diffraction techniques and UV-VIS spectrophotometer have confirmed the structural and the optical properties the prepared thin films. CdO thin films were found to have polycrystalline nature with cubic rock salt phase. The crystallinity being improved, the FWHM decreases and the grain size of the CdO thin films increased with increasing the annealing temperatures. The average grain size is observed in the range (23.97 -30.47) nm which indicate that the prepared film have a nanocrystalline structure. From optical analysis, it can be seen that there are an increases in the absorbance and decreases in the trancemittance of the prepared films with the increasing of the annealing temperatures.The optical band gap decreases from 2.556, to 2.081 eV with increasing of annealing temperature fromm 300 to 400° C, this suggested that the optical band gap for CdO nanocrystalline thin films is strongly dependent on the annealing temperature.
In this work we report on the results obtained on NbN x thin films grown on both common glass and... more In this work we report on the results obtained on NbN x thin films grown on both common glass and silicon wafer substrates by RF magnetron sputtering at different substrate temperatures and different target power supplies. The crystalinity, morphology and surface composition of the deposited films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively.
ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their ele... more ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation BixTiyOz thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti6Al4V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi3+ and Ti4+.
This paper reports the influence of substrate temperature on the structure, morphology and corros... more This paper reports the influence of substrate temperature on the structure, morphology and corrosion resistance of ZrO x N y /ZrO 2 thin films deposited on 304 stainless steel using radio frequency sputtering (RF sputtering). Structural analysis was carried out by X-ray diffraction (XRD); morphological analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and surface chemical analysis was determined using X-ray photoelectron spectroscopy (XPS). XRD data showed that the films deposited at 300 • C (573 K) and 350 • C (623 K) result in the growth of a monoclinic zirconium oxynitride phase with preferential orientation along the (−1 1 1) plane, while at 14 • C (287 K) the predominant phase is of polycrystalline ZrO 2 . The corrosion results indicate that the coatings provide good resistance to corrosion in chloride-containing media, being better in the film deposited at 350 • C (623 K). SEM analysis demonstrated the homogeneity of the films deposited at the three temperatures; AFM studies established the average roughness of the films to be 4.25 nm. The binding energies of the Zr 3d, N 1s, and O 1s core levels determined by XPS were all compatible with the formation of a zirconium oxynitride and zirconium oxide in the surface of the film. ZrO x N y /ZrO 2 thin films are promising candidates for increasing the corrosion resistance of the steels in chloride-rich environments.
Ceramics International, 2014
Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering techn... more Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering technique on (100) silicon substrates. In the process, annealing was performed in both oxygen and dry air atmospheres at 600 1C for 30 and 120 min. The structure of the thin films was characterized through X-ray diffraction (XRD), and the ferroelectric response was determined with measurements of piezoelectric force microscopy (PFM). Bi 4 Ti 3 O 12 with a predominant orthorhombic phase was obtained in the annealed thin films. All the annealed films exhibited the characteristic hysteresis and butterfly loops of ferroelectric materials. Thermal annealing of Bi x Ti y O z films in an atmosphere of air for 30 min resulted in the highest d 33 value of 78 7 14 pm/V, which decreased to 64 7 26 pm/V for 120 min. On the other hand, annealing in an oxygen atmosphere produced Bi x Ti y O z films with more uniform d 33 values, 54 7 3 pm/V and 427 6 pm/V for 30 and 120 min, respectively. Ferroelectric coefficient values decreased with the increase of annealing time in an oxidant atmosphere, which can be explained by the vacancies present. These results are consistent with the experimental measurements carried out in other investigations.
Surface and Coatings Technology, 2014
In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating techniq... more In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating technique, by depoited four layers of mixtuer solution contians Cadmium acetate dehydrate, Triethylamine, glycerol and ethanol.The spin coated solution were dried at 100°C and annealied at (300,350 and 400 o C temperatures ). The x-ray diffraction techniques and UV-VIS spectrophotometer have confirmed the structural and the optical properties the prepared thin films. CdO thin films were found to have polycrystalline nature with cubic rock salt phase. The crystallinity being improved, the FWHM decreases and the grain size of the CdO thin films increased with increasing the annealing temperatures. The average grain size is observed in the range (23.97 -30.47) nm which indicate that the prepared film have a nanocrystalline structure. From optical analysis, it can be seen that there are an increases in the absorbance and decreases in the trancemittance of the prepared films with the increasing of the annealing temperatures.The optical band gap decreases from 2.556, to 2.081 eV with increasing of annealing temperature fromm 300 to 400° C, this suggested that the optical band gap for CdO nanocrystalline thin films is strongly dependent on the annealing temperature.
In this work we report on the results obtained on NbN x thin films grown on both common glass and... more In this work we report on the results obtained on NbN x thin films grown on both common glass and silicon wafer substrates by RF magnetron sputtering at different substrate temperatures and different target power supplies. The crystalinity, morphology and surface composition of the deposited films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively.
ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their ele... more ABSTRACT The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation BixTiyOz thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti6Al4V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi3+ and Ti4+.
This paper reports the influence of substrate temperature on the structure, morphology and corros... more This paper reports the influence of substrate temperature on the structure, morphology and corrosion resistance of ZrO x N y /ZrO 2 thin films deposited on 304 stainless steel using radio frequency sputtering (RF sputtering). Structural analysis was carried out by X-ray diffraction (XRD); morphological analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and surface chemical analysis was determined using X-ray photoelectron spectroscopy (XPS). XRD data showed that the films deposited at 300 • C (573 K) and 350 • C (623 K) result in the growth of a monoclinic zirconium oxynitride phase with preferential orientation along the (−1 1 1) plane, while at 14 • C (287 K) the predominant phase is of polycrystalline ZrO 2 . The corrosion results indicate that the coatings provide good resistance to corrosion in chloride-containing media, being better in the film deposited at 350 • C (623 K). SEM analysis demonstrated the homogeneity of the films deposited at the three temperatures; AFM studies established the average roughness of the films to be 4.25 nm. The binding energies of the Zr 3d, N 1s, and O 1s core levels determined by XPS were all compatible with the formation of a zirconium oxynitride and zirconium oxide in the surface of the film. ZrO x N y /ZrO 2 thin films are promising candidates for increasing the corrosion resistance of the steels in chloride-rich environments.
Ceramics International, 2014
Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering techn... more Bismuth titanate (Bi x Ti y O z ) thin films were grown using the r.f. magnetron sputtering technique on (100) silicon substrates. In the process, annealing was performed in both oxygen and dry air atmospheres at 600 1C for 30 and 120 min. The structure of the thin films was characterized through X-ray diffraction (XRD), and the ferroelectric response was determined with measurements of piezoelectric force microscopy (PFM). Bi 4 Ti 3 O 12 with a predominant orthorhombic phase was obtained in the annealed thin films. All the annealed films exhibited the characteristic hysteresis and butterfly loops of ferroelectric materials. Thermal annealing of Bi x Ti y O z films in an atmosphere of air for 30 min resulted in the highest d 33 value of 78 7 14 pm/V, which decreased to 64 7 26 pm/V for 120 min. On the other hand, annealing in an oxygen atmosphere produced Bi x Ti y O z films with more uniform d 33 values, 54 7 3 pm/V and 427 6 pm/V for 30 and 120 min, respectively. Ferroelectric coefficient values decreased with the increase of annealing time in an oxidant atmosphere, which can be explained by the vacancies present. These results are consistent with the experimental measurements carried out in other investigations.
Surface and Coatings Technology, 2014
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Papers Vol. 7 núm. 14 julio-diciembre 2011 by J.E. Alfonso
Papers by J.E. Alfonso