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Titre : Etude des proprietes structurales et optiques des nanocomposites Ag/SiO2 Type de document : texte imprimé Auteurs : Zakaria Nouicer, Auteur ; N. Keghouche, Directeur de thèse Editeur : Constantine : Université Mentouri Constantine Année de publication : 2015 Importance : 77 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : Nanocomposites Argent Silice SiO2 Silver Silica SiO2 Ag/SiO2 ?????????? ??? ????? SiO2 ????? ????????? ??? ??????? SiO2/Ag Index. décimale : 530 Physique Résumé : In this work, composite silver / silica were studied. In a first step, the Ag+ ions of various compositions (2.5, 5, 7.5 and 10%) were fixed on the silica by ion exchange. In a second step, the samples were annealed in air at temperatures ranging from 100 to 700° C. Several experimental techniques (SEM, XRD, FTIR, UV-Visible) were used to characterize the samples at various stages of development.
The X-ray diffraction has identified several phases formed (Ag2Si2O5; Ag2SiO3 ; Ag3Si and Ag) for the respective proportions: 2.5; 5; 7.5 and 10% of Ag+ ions/SiO2.
After heat treatment, for a charge of 5%, the X-ray diffraction revealed the formation of silver silicates (Ag4SiO4; Ag6Si2O7; Ag10Si4O13) for temperatures below 500°C and Ag phase to higher temperatures (600 and 700°C).
FTIR spectra of the samples Ag/SiO2 present five bands in the region 400 to 2000 cm-1 assigned to the vibration: Si-O-Si, Ag-W, Ag-SO4, Si-O and Si-OH. The spectrum of the sample content of 2.5% Ag+ has well-resolved peaks. The increase of the Ag+ ions load causes an overlap of peaks relating to the groups: Si-O and Si-OH.
An FTIR spectrum of displacement toward the low wave numbers was observed after annealing at 200° C. For larger annealing temperatures (300 to 700° C), the spectrum is moved in the opposite direction. This correlates with the formation of large silver nanoparticles.
The UV-visible absorption spectrum of nanocomposites Ag/SiO2 has a wide band in the UV region (300 to 370 nm) for the different ion contents Ag+/SiO2. This absorption is attributed to the surface plasmon resonance. Following the heat treatment, a shift of this band to the blue is observed
Diplôme : Magistère En ligne : ../theses/physique/NOU6767.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9846 Etude des proprietes structurales et optiques des nanocomposites Ag/SiO2 [texte imprimé] / Zakaria Nouicer, Auteur ; N. Keghouche, Directeur de thèse . - Constantine : Université Mentouri Constantine, 2015 . - 77 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Nanocomposites Argent Silice SiO2 Silver Silica SiO2 Ag/SiO2 ?????????? ??? ????? SiO2 ????? ????????? ??? ??????? SiO2/Ag Index. décimale : 530 Physique Résumé : In this work, composite silver / silica were studied. In a first step, the Ag+ ions of various compositions (2.5, 5, 7.5 and 10%) were fixed on the silica by ion exchange. In a second step, the samples were annealed in air at temperatures ranging from 100 to 700° C. Several experimental techniques (SEM, XRD, FTIR, UV-Visible) were used to characterize the samples at various stages of development.
The X-ray diffraction has identified several phases formed (Ag2Si2O5; Ag2SiO3 ; Ag3Si and Ag) for the respective proportions: 2.5; 5; 7.5 and 10% of Ag+ ions/SiO2.
After heat treatment, for a charge of 5%, the X-ray diffraction revealed the formation of silver silicates (Ag4SiO4; Ag6Si2O7; Ag10Si4O13) for temperatures below 500°C and Ag phase to higher temperatures (600 and 700°C).
FTIR spectra of the samples Ag/SiO2 present five bands in the region 400 to 2000 cm-1 assigned to the vibration: Si-O-Si, Ag-W, Ag-SO4, Si-O and Si-OH. The spectrum of the sample content of 2.5% Ag+ has well-resolved peaks. The increase of the Ag+ ions load causes an overlap of peaks relating to the groups: Si-O and Si-OH.
An FTIR spectrum of displacement toward the low wave numbers was observed after annealing at 200° C. For larger annealing temperatures (300 to 700° C), the spectrum is moved in the opposite direction. This correlates with the formation of large silver nanoparticles.
The UV-visible absorption spectrum of nanocomposites Ag/SiO2 has a wide band in the UV region (300 to 370 nm) for the different ion contents Ag+/SiO2. This absorption is attributed to the surface plasmon resonance. Following the heat treatment, a shift of this band to the blue is observed
Diplôme : Magistère En ligne : ../theses/physique/NOU6767.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9846 Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). / Imene Lamiri
Titre : Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). Type de document : texte imprimé Auteurs : Imene Lamiri, Auteur ; Djamel Hamana, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2018 Importance : 133 f. Note générale : 2 copies imprimées disponibles
Langues : Anglais (eng) Tags : 12 and 18-carat gold silver copper thermal analyses precipitation dendrite mechanical spectroscopy anelasticity internal dissipation Zener relaxation twin boundary relaxation grainboundaries sliding relaxation 12 et 18 carats or argent cuivre analyses thermiques précipitation spectroscopie mécanique anélasticité dissipation interne relaxation de Zener relaxation des joints de macles joints de grains 21? 18 ????? ???? ??? ???????? ???????? ??????? ???? ???? ??????? ??????????? ??? ??? ???????
??????? ??????? ???? ???? ??????? ????????? ??????? ?????? ??????Index. décimale : 530 Physique Résumé : This work is motivated by a scientific interest in gaining a better understanding of the phase transformations that govern the mechanical properties of gold alloys due to their huge industrial importance such as their common use in jewelry applications, luxury watch making, catalyses, electronic industries ...etc... The selected alloys fall in one of two categories of yellow gold, based on the binary system of GoldCopper and the ternary system Gold–Copper–Silver In this thesis, selected alloys from the two categories are studied, using two principal compositions of 12 and 18-carat. The study starts primarily by the thermal identification of the possible anomalies that could happen during the heating from the room temperature up to 973K (temperature near to the industrial use -1023K). Un expectable anomaly at low temperature has been noticed by the thermal analyses while the primary state before the heating process was the disorder. The fact that has orientate the study to the use of surface techniques in order to determine the relationship of the thermally detected anomalies with the surface aspect of the alloys. The study has lead to highlight new kind of metastable phase transition that precede the ordering reaction in gold alloys at low temperature presented in dendrite shape of precipitated phase on the surface. The participation of the silver in the alloy composition leads to accelerate the ordering reaction. 18-carat binary composition, has been treated in the thorough way in terms of structural study. Using the in-situ temperature XRD measurement with data acquisition frequency of 1 pattern/1.1min. Phase transition sequences and temperatures have been determined over the fitting of the obtained patterns and through the following of the behavior evolution of the intensities of the typical peak of every phase as well as the atomic volume occupancy. The analysis and interpretation of the experimental data stemming from the mechanical spectroscopy reveal three important anelastic relaxations (internal dissipation processes), which dominate the mechanical loss spectrum of the binary 18-carat alloy above room temperature. A Zener relaxation, due to directional ordering of atoms in the substitutional solid solution, occurs nearby the
phase transition AuCuI - AuCuII upon heating and the classic Zener relaxation peak accompanies the phase transition A1 - AuCuI + AuCuII upon cooling. An antiphase boundaries relaxation peak has been highlighted as typical peak of the AuCuII. Grain boundaries sliding relaxation peak has been attributed to the pure disordered phase
Diplôme : Doctorat En ligne : ../theses/physique/LAM7381.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11031 Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). [texte imprimé] / Imene Lamiri, Auteur ; Djamel Hamana, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2018 . - 133 f.
2 copies imprimées disponibles
Langues : Anglais (eng)
Tags : 12 and 18-carat gold silver copper thermal analyses precipitation dendrite mechanical spectroscopy anelasticity internal dissipation Zener relaxation twin boundary relaxation grainboundaries sliding relaxation 12 et 18 carats or argent cuivre analyses thermiques précipitation spectroscopie mécanique anélasticité dissipation interne relaxation de Zener relaxation des joints de macles joints de grains 21? 18 ????? ???? ??? ???????? ???????? ??????? ???? ???? ??????? ??????????? ??? ??? ???????
??????? ??????? ???? ???? ??????? ????????? ??????? ?????? ??????Index. décimale : 530 Physique Résumé : This work is motivated by a scientific interest in gaining a better understanding of the phase transformations that govern the mechanical properties of gold alloys due to their huge industrial importance such as their common use in jewelry applications, luxury watch making, catalyses, electronic industries ...etc... The selected alloys fall in one of two categories of yellow gold, based on the binary system of GoldCopper and the ternary system Gold–Copper–Silver In this thesis, selected alloys from the two categories are studied, using two principal compositions of 12 and 18-carat. The study starts primarily by the thermal identification of the possible anomalies that could happen during the heating from the room temperature up to 973K (temperature near to the industrial use -1023K). Un expectable anomaly at low temperature has been noticed by the thermal analyses while the primary state before the heating process was the disorder. The fact that has orientate the study to the use of surface techniques in order to determine the relationship of the thermally detected anomalies with the surface aspect of the alloys. The study has lead to highlight new kind of metastable phase transition that precede the ordering reaction in gold alloys at low temperature presented in dendrite shape of precipitated phase on the surface. The participation of the silver in the alloy composition leads to accelerate the ordering reaction. 18-carat binary composition, has been treated in the thorough way in terms of structural study. Using the in-situ temperature XRD measurement with data acquisition frequency of 1 pattern/1.1min. Phase transition sequences and temperatures have been determined over the fitting of the obtained patterns and through the following of the behavior evolution of the intensities of the typical peak of every phase as well as the atomic volume occupancy. The analysis and interpretation of the experimental data stemming from the mechanical spectroscopy reveal three important anelastic relaxations (internal dissipation processes), which dominate the mechanical loss spectrum of the binary 18-carat alloy above room temperature. A Zener relaxation, due to directional ordering of atoms in the substitutional solid solution, occurs nearby the
phase transition AuCuI - AuCuII upon heating and the classic Zener relaxation peak accompanies the phase transition A1 - AuCuI + AuCuII upon cooling. An antiphase boundaries relaxation peak has been highlighted as typical peak of the AuCuII. Grain boundaries sliding relaxation peak has been attributed to the pure disordered phase
Diplôme : Doctorat En ligne : ../theses/physique/LAM7381.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11031 Exemplaires
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Titre : Nanoagregats de Nickel et d’Argent : Mecanismes de formation et proprietes. Type de document : texte imprimé Auteurs : Mohamed Larbi Hioul, Auteur ; Nassira Keghouche, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2018 Importance : 124 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : clusters agrégats nickel argent radiolyse pulsée aggregates silver pulse radiolysis ??????????? ?????? ????? ????????????????? Index. décimale : 530 Physique Résumé : Metallic aggregates in colloidal phases or supported aggregates attract increasing attention of researchers because of the wide range of possible applications (catalysis, environment, non-linear optics, biology and medicine). Radiolysis ranks among the most effective methods for the reduction of ions, giving the possibility of synthesis of aggregates of atoms. It is a powerful method to control the size of the particles, their location on the surface or volume. In the first part of this work, the morphological and structural properties of silver aggregates supported on silica were studied. X-ray diffraction identified the Ag6Si2O7 phase for different Ag+ ion charges as well as heat-treated samples. The FTIR spectroscopy study of Ag/SiO2 samples revealed the vibrations of Si-O-Si, Si-OH, Ag-O and Ag-SO4 bonds at the respective wave numbers 468, 810, 615 and 641 cm-1. The study of the optical properties of Ag/SiO2 nanoagreggates by UV- visible spectrophotometry showed the presence, in addition to a broadband in the visible range, three peaks in the UV domain. After reduction under hydrogen, the metal Ag phase of nanometric size was identified by XRD. In the second part, we studied, by time-resolved pulse radiolysis, nickel clusters in suspension. The formation of Ni+ ions and then those of nickel atoms was observed. The ionizing radiation generation of nickel aggregates in solution was observed for the first time live during this work.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/HIO7384.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11034 Nanoagregats de Nickel et d’Argent : Mecanismes de formation et proprietes. [texte imprimé] / Mohamed Larbi Hioul, Auteur ; Nassira Keghouche, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2018 . - 124 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : clusters agrégats nickel argent radiolyse pulsée aggregates silver pulse radiolysis ??????????? ?????? ????? ????????????????? Index. décimale : 530 Physique Résumé : Metallic aggregates in colloidal phases or supported aggregates attract increasing attention of researchers because of the wide range of possible applications (catalysis, environment, non-linear optics, biology and medicine). Radiolysis ranks among the most effective methods for the reduction of ions, giving the possibility of synthesis of aggregates of atoms. It is a powerful method to control the size of the particles, their location on the surface or volume. In the first part of this work, the morphological and structural properties of silver aggregates supported on silica were studied. X-ray diffraction identified the Ag6Si2O7 phase for different Ag+ ion charges as well as heat-treated samples. The FTIR spectroscopy study of Ag/SiO2 samples revealed the vibrations of Si-O-Si, Si-OH, Ag-O and Ag-SO4 bonds at the respective wave numbers 468, 810, 615 and 641 cm-1. The study of the optical properties of Ag/SiO2 nanoagreggates by UV- visible spectrophotometry showed the presence, in addition to a broadband in the visible range, three peaks in the UV domain. After reduction under hydrogen, the metal Ag phase of nanometric size was identified by XRD. In the second part, we studied, by time-resolved pulse radiolysis, nickel clusters in suspension. The formation of Ni+ ions and then those of nickel atoms was observed. The ionizing radiation generation of nickel aggregates in solution was observed for the first time live during this work.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/HIO7384.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11034 Exemplaires
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