4 résultat(s) recherche sur le tag 'absorption UV-visible'    

Elaboration et caractérisation de nanocomposites hybrides / Bariza Troudi  

Public ISBD Titre : Elaboration et caractérisation de nanocomposites hybrides : Oxydes métalliques/polymères Type de document : texte imprimé Auteurs : Bariza Troudi, Auteur ; Ouahiba Halimi, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 121 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : Synthèse hydrothermale  Nanocomposites  Films minces  CuO/PS  CuO/PVC  PbO/PS  PbO/PVC  DRX  FT-IR  Raman  AFM  Absorption UV-Visible  photoluminescence  Hydrothermal synthesis  thin films  UV-Visible Absorption  ?????? ??????  ????? ?????  ???????? ??? ????????- ????  ???????? ?????? Index. décimale : 530 Physique Résumé : Thin films of metal oxides/polymers nanocomposites were deposited on glass substrates by Spin-Coating and Dip-Coating techniques. The nanocomposites were elaborated by inserting, in the matrices of polystyrene (PS) and polyvinyl chloride (PVC) polymers, of nanoparticles of metal oxides such as copper oxide (CuO) and lead oxide (PbO). The nanoparticles of semiconductor CuO and PbO were synthesized beforehand by the hydrothermal method. The xray diffraction characterization of the obtained powders have revealed a monoclinic phase for CuO crystallites and an orthorhombic phase for PbO. The size of the crystallites of the two semiconductors is of a nanometic order. Calcul the of gap energy indicate a shift towards high energies compared to massive crystals. This shift is due to the effect of the quantum confinement induced by the nanometric size of the crystallites of the semiconductors. These nanocrystals are used for the preparation of the nanocomposites of CuO/PS, CuO/PVC, PbO/PS and PbO/PVC by simple insertion of CuO and PbO nanoparticles in the PS and PVC polymers. The analysis of the elaborated nanocomposites by X-ray diffraction has allowed to notice the incorporation of the CuO and PbO crystallites into the PS and PVC polymers matrixes and analysis by Raman and infrared spectroscopies has confirmed the presence of CuO and PbO crystallites in the PS and PVC matrixes by revealing specific vibration modes to the Cu-O and Pb-O bonds. The surface morphology and topography of thin films of nanocomposites were highlighted with the help of atomic force microscopy (AFM) and have shown homogeneous dispersion of CuO and PbO crystallites and a low surface roughness. the characterization by measurement of the optical absorption in the UV-Visible domain allows to observe the increase in optical absorption which is attributed to CuO and PbO nanocrystallites because PS and PVC are optically transparent in the UV-Visible domain. A shift of the gap energy of the nanocomposites compared with the gap energy of the pure polymers and the massive crystallites of CuO and PbO was observed. This variation in gap energy is the result of the new optical behavior of the prepared nanocomposites. The optical characterization by the measure of the photoluminescence has shown that the elaborated samples present intense luminescence bands in the visible range, hence the possibility of consider these matrices as optically active media and can be used for the making devices of specific optics properties. Diplôme : Doctorat en sciences En ligne : ../theses/physique/TRO7142.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10460 Elaboration et caractérisation de nanocomposites hybrides : Oxydes métalliques/polymères [texte imprimé] / Bariza Troudi, Auteur ; Ouahiba Halimi, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 121 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : Synthèse hydrothermale  Nanocomposites  Films minces  CuO/PS  CuO/PVC  PbO/PS  PbO/PVC  DRX  FT-IR  Raman  AFM  Absorption UV-Visible  photoluminescence  Hydrothermal synthesis  thin films  UV-Visible Absorption  ?????? ??????  ????? ?????  ???????? ??? ????????- ????  ???????? ?????? Index. décimale : 530 Physique Résumé : Thin films of metal oxides/polymers nanocomposites were deposited on glass substrates by Spin-Coating and Dip-Coating techniques. The nanocomposites were elaborated by inserting, in the matrices of polystyrene (PS) and polyvinyl chloride (PVC) polymers, of nanoparticles of metal oxides such as copper oxide (CuO) and lead oxide (PbO). The nanoparticles of semiconductor CuO and PbO were synthesized beforehand by the hydrothermal method. The xray diffraction characterization of the obtained powders have revealed a monoclinic phase for CuO crystallites and an orthorhombic phase for PbO. The size of the crystallites of the two semiconductors is of a nanometic order. Calcul the of gap energy indicate a shift towards high energies compared to massive crystals. This shift is due to the effect of the quantum confinement induced by the nanometric size of the crystallites of the semiconductors. These nanocrystals are used for the preparation of the nanocomposites of CuO/PS, CuO/PVC, PbO/PS and PbO/PVC by simple insertion of CuO and PbO nanoparticles in the PS and PVC polymers. The analysis of the elaborated nanocomposites by X-ray diffraction has allowed to notice the incorporation of the CuO and PbO crystallites into the PS and PVC polymers matrixes and analysis by Raman and infrared spectroscopies has confirmed the presence of CuO and PbO crystallites in the PS and PVC matrixes by revealing specific vibration modes to the Cu-O and Pb-O bonds. The surface morphology and topography of thin films of nanocomposites were highlighted with the help of atomic force microscopy (AFM) and have shown homogeneous dispersion of CuO and PbO crystallites and a low surface roughness. the characterization by measurement of the optical absorption in the UV-Visible domain allows to observe the increase in optical absorption which is attributed to CuO and PbO nanocrystallites because PS and PVC are optically transparent in the UV-Visible domain. A shift of the gap energy of the nanocomposites compared with the gap energy of the pure polymers and the massive crystallites of CuO and PbO was observed. This variation in gap energy is the result of the new optical behavior of the prepared nanocomposites. The optical characterization by the measure of the photoluminescence has shown that the elaborated samples present intense luminescence bands in the visible range, hence the possibility of consider these matrices as optically active media and can be used for the making devices of specific optics properties. Diplôme : Doctorat en sciences En ligne : ../theses/physique/TRO7142.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10460

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Etude des propriétés structurales et optiques des matrices cristallines KCl et KBr dopées par les agrégats des terres rares Er, Ce et Lu / Sadek Kara  

Public ISBD Titre : Etude des propriétés structurales et optiques des matrices cristallines KCl et KBr dopées par les agrégats des terres rares Er, Ce et Lu Type de document : texte imprimé Auteurs : Sadek Kara, Auteur ; M. Sebais, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 104 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : chlorure de terre rare (ErCl3, CeCl3)  oxyde de terre rare Lu2O3  Czochralski  DRX  FT-IR, ?-Ramn  absorption UV-visible  photoluminescence  radio-luminescence  Rare earth chloride (ErCl3, CeCl3)  rare earth oxide Lu2O3  UV-Visible absorption  Radio-luminescence  ?????? ??????? ??????? ??????? )  (CeCl3?ErCl3????? ??????? ??????? ???????)  (Lu2O3????? ???????????????? ????  X???????? ??????  ???? ????? ? ?????? ?? ??? ??????? ??????? ?????? Index. décimale : 530 Physique Résumé : The aim of this work is to develop and characterize the single crystals of alkali halide (KCl and KBr) doped with rare earth elements (Er, Ce and Lu) using the crystal growth technique from melt phase according to the principle of the Czochralski method. The single crystals obtained are on cylindrical morphology. For the purposes of their characterization, the single crystals are cut by pellet cleavage whose plane faces are perpendicular to the growth axis which is parallel to the crystallographic axis of KCl or KBr. Structural studies on elaborated materials using X-ray diffraction, FT-IR and Raman spectroscopies have shown that the KCl and KBr monocrystals (pure and doped) have a monocrystalline character, and in these crystalline matrices theaggregates of rare earths elements (ErCl3, CeCl3 and Lu2O3) are incorporated. The presence of these aggregates induced stresses in the crystal lattice of the matrices KCl and KBr. Certain impurities such as H2O and CO2 have also been revealed and their come from the environment during the growth operation (uncontrolled atmosphere) or the characterization of the samples. Optical investigations by absorption, photoluminescence and radioluminescence were carried out to demonstrate the optical properties of KCl and KBr single crystals doped with rare earth elements Er, Ce and Lu and also to confirm the presence of dopants in the host matrices. Observation of the optical absorption spectra shows that all the samples studied are transparent in the IR domain but have an important absorption in the UV-VIS domain. Bands corresponding to the absorption by the doping elements and to the colored centers present in the matrices KCl and KBr are also visible on the spectra. The photoluminescence of the samples shows an emission bands due to radiative electronic transitions of the rare earth elements, demonstrating that the matrices studied can be considered as luminophores. The relatively high concentration of the doping elements leads to a decrease in the intensity of the observed luminescence bands; this decrease may be due to a mutual influence of the rare earth atoms incorporated in the KCl and KBr matrices. The analysis by radio-luminescence shows intense emission bands and shows that the elaborated materials can be used as scintillators for the detection of X-rays. Diplôme : Doctorat en sciences En ligne : ../theses/physique/KAR7113.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10488 Etude des propriétés structurales et optiques des matrices cristallines KCl et KBr dopées par les agrégats des terres rares Er, Ce et Lu [texte imprimé] / Sadek Kara, Auteur ; M. Sebais, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 104 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : chlorure de terre rare (ErCl3, CeCl3)  oxyde de terre rare Lu2O3  Czochralski  DRX  FT-IR, ?-Ramn  absorption UV-visible  photoluminescence  radio-luminescence  Rare earth chloride (ErCl3, CeCl3)  rare earth oxide Lu2O3  UV-Visible absorption  Radio-luminescence  ?????? ??????? ??????? ??????? )  (CeCl3?ErCl3????? ??????? ??????? ???????)  (Lu2O3????? ???????????????? ????  X???????? ??????  ???? ????? ? ?????? ?? ??? ??????? ??????? ?????? Index. décimale : 530 Physique Résumé : The aim of this work is to develop and characterize the single crystals of alkali halide (KCl and KBr) doped with rare earth elements (Er, Ce and Lu) using the crystal growth technique from melt phase according to the principle of the Czochralski method. The single crystals obtained are on cylindrical morphology. For the purposes of their characterization, the single crystals are cut by pellet cleavage whose plane faces are perpendicular to the growth axis which is parallel to the crystallographic axis of KCl or KBr. Structural studies on elaborated materials using X-ray diffraction, FT-IR and Raman spectroscopies have shown that the KCl and KBr monocrystals (pure and doped) have a monocrystalline character, and in these crystalline matrices theaggregates of rare earths elements (ErCl3, CeCl3 and Lu2O3) are incorporated. The presence of these aggregates induced stresses in the crystal lattice of the matrices KCl and KBr. Certain impurities such as H2O and CO2 have also been revealed and their come from the environment during the growth operation (uncontrolled atmosphere) or the characterization of the samples. Optical investigations by absorption, photoluminescence and radioluminescence were carried out to demonstrate the optical properties of KCl and KBr single crystals doped with rare earth elements Er, Ce and Lu and also to confirm the presence of dopants in the host matrices. Observation of the optical absorption spectra shows that all the samples studied are transparent in the IR domain but have an important absorption in the UV-VIS domain. Bands corresponding to the absorption by the doping elements and to the colored centers present in the matrices KCl and KBr are also visible on the spectra. The photoluminescence of the samples shows an emission bands due to radiative electronic transitions of the rare earth elements, demonstrating that the matrices studied can be considered as luminophores. The relatively high concentration of the doping elements leads to a decrease in the intensity of the observed luminescence bands; this decrease may be due to a mutual influence of the rare earth atoms incorporated in the KCl and KBr matrices. The analysis by radio-luminescence shows intense emission bands and shows that the elaborated materials can be used as scintillators for the detection of X-rays. Diplôme : Doctorat en sciences En ligne : ../theses/physique/KAR7113.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10488

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Etude structurale et optique de matériaux composites / Mouloud Hemara  

Public ISBD Titre : Etude structurale et optique de matériaux composites Type de document : texte imprimé Auteurs : Mouloud Hemara, Auteur ; Zeineddine Ouili, Directeur de thèse Editeur : Constantine : Université Mentouri Constantine Année de publication : 2015 Importance : 75 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : composites  nanocomposites  oxyde niobium (Nb2O5 )  Czochralski  DRX  ?-Raman  FT-IR  absorption UV-Visible  radioluminescence  niobium oxide ( Nb2O5 )  XRD  UV-Visible absorption  ????????  ?????? ??????  ????? ????????? Nb2O5  ????? ???? ?????  ?????? ????  ??? ????? ??????? ????? ???????  ???????? ?????? ?? ?????? ?????? ?????? ? ??? ????????  ????????? ??????? Index. décimale : 530 Physique Résumé : This work is the development of single crystals KBr and KCl pure and doped with Nb crystallites was carried out by the drawing method according to the principle of Czochralski growth . The structural study and optical different matrices , alkali halides to know the effects of doping on their properties. The structural analysis of the samples prepared was carried out by the X-ray diffraction and IR spectroscopy and micro -Raman . XRD revealed the incorporation of Nb crystallite in the crystal matrix , and produces another Nano phase ( Nb2O5 ) . The μ -Raman and FT-IR spectroscopy to confirm the results of the characterization by X-ray diffraction as regards the presence of the phase Nb2O5 and existed the Nb- O chemical bond in the crystal matrices KBr and KCl . The optical absorption study for the nanocomposites prepared Nb / Nb and KBr / KCl show a transparent matrices in the Visible and Ultraviolet related field , When these matrices are doped with Nb2O5 nanocrystallites their optical gap decrease. The optical characterization radioluminescence for samples prepared shown that this low-intensity luminescence in the visible range when excited by radiation X. Diplôme : Magistère En ligne : ../theses/physique/HEM6747.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9869 Etude structurale et optique de matériaux composites [texte imprimé] / Mouloud Hemara, Auteur ; Zeineddine Ouili, Directeur de thèse . - Constantine : Université Mentouri Constantine, 2015 . - 75 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : composites  nanocomposites  oxyde niobium (Nb2O5 )  Czochralski  DRX  ?-Raman  FT-IR  absorption UV-Visible  radioluminescence  niobium oxide ( Nb2O5 )  XRD  UV-Visible absorption  ????????  ?????? ??????  ????? ????????? Nb2O5  ????? ???? ?????  ?????? ????  ??? ????? ??????? ????? ???????  ???????? ?????? ?? ?????? ?????? ?????? ? ??? ????????  ????????? ??????? Index. décimale : 530 Physique Résumé : This work is the development of single crystals KBr and KCl pure and doped with Nb crystallites was carried out by the drawing method according to the principle of Czochralski growth . The structural study and optical different matrices , alkali halides to know the effects of doping on their properties. The structural analysis of the samples prepared was carried out by the X-ray diffraction and IR spectroscopy and micro -Raman . XRD revealed the incorporation of Nb crystallite in the crystal matrix , and produces another Nano phase ( Nb2O5 ) . The μ -Raman and FT-IR spectroscopy to confirm the results of the characterization by X-ray diffraction as regards the presence of the phase Nb2O5 and existed the Nb- O chemical bond in the crystal matrices KBr and KCl . The optical absorption study for the nanocomposites prepared Nb / Nb and KBr / KCl show a transparent matrices in the Visible and Ultraviolet related field , When these matrices are doped with Nb2O5 nanocrystallites their optical gap decrease. The optical characterization radioluminescence for samples prepared shown that this low-intensity luminescence in the visible range when excited by radiation X. Diplôme : Magistère En ligne : ../theses/physique/HEM6747.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9869

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Elaboration et caractérisation structurale et optique des nanocristaux du semiconducteur Sb2O3 et de l'oxyde Y2O3 dispersés dans les matrices cristallines des halogénures alcalins KBr, KCl et NaCl / Lazhar Bouhdjer    

Public ISBD Titre : Elaboration et caractérisation structurale et optique des nanocristaux du semiconducteur Sb2O3 et de l'oxyde Y2O3 dispersés dans les matrices cristallines des halogénures alcalins KBr, KCl et NaCl Type de document : texte imprimé Auteurs : Lazhar Bouhdjer, Auteur ; M. Sebais, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2013 Importance : 93 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : semi-conducteur Sb2O3  oxyde de terre rare Y2O3  Czochralski  DRX  FT-IR  ?-Ramn  absorption UV-Visible  photoluminescence  semiconductor (Sb2O3)  rare earth oxide (Y2O3)  XRD  IR  ?- Ramn  Uvi-Vis  ???????? ??????????? ????? ?????????  ???????? ??????  ???? ????? ? ?????? ?? ??? ???????  ?????? ?????????? ?????? MEB  (Sb2O3)??? ??????  (Y2O3)?????? ?????? ?????? X Index. décimale : 530 Physique Résumé : Preparation and structural and optical characterization of semiconductor nanocrystals of Sb2O3 and Y2O3 oxide dispersed in a crystalline matrices of alkali halides KBr, KCl and NaCl. In this work antimony oxide (Sb2O3) and yttrium oxide (Y2O3) nanocrystals doped KBr, KCl and NaCl single crystals have been grown by Czochralski (Cz) method. The effects of doping on the structural and optical properties of the host matrices have been studied. The structural studies of samples were performed by XRD, μ-Raman, IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The treatment of XRD spectrum confirms the existence of crystallites of dopants (Sb2O3 and Y2O3) in the nanometer regime; on the other hand, the existence of the stable monoclinic phase crystallites (Y2O3) under atmospheric conditions reconfirms presence of (Y2O3) in nanoscale. Studies by μ-Raman and IR confirmed the presence of chemical bonds Y—O and Sb—O in the different matrices. The morphological study using the scanning electron microscope (SEM) shows that the micron grains scattered on the surface. The volume of these aggregates is due to the fact that the nanocrystals have a tendency to reduce its free energy (Gibbs energy) of surface. The optical absorption and photoluminescence shows that the optical gaps of the crystallites (Sb2O3 and Y2O3) have been shifted to the high energy due to the quantum confinement effect of the charges. The samples have important intense luminescence properties in the ultraviolet range. This feature makes these materials candidates which might come in the manufacture of components for optical systems using shorter wavelengths. Diplôme : Doctorat en sciences En ligne : ../theses/physique/BOU6378.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9379 Elaboration et caractérisation structurale et optique des nanocristaux du semiconducteur Sb2O3 et de l'oxyde Y2O3 dispersés dans les matrices cristallines des halogénures alcalins KBr, KCl et NaCl [texte imprimé] / Lazhar Bouhdjer, Auteur ; M. Sebais, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2013 . - 93 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : semi-conducteur Sb2O3  oxyde de terre rare Y2O3  Czochralski  DRX  FT-IR  ?-Ramn  absorption UV-Visible  photoluminescence  semiconductor (Sb2O3)  rare earth oxide (Y2O3)  XRD  IR  ?- Ramn  Uvi-Vis  ???????? ??????????? ????? ?????????  ???????? ??????  ???? ????? ? ?????? ?? ??? ???????  ?????? ?????????? ?????? MEB  (Sb2O3)??? ??????  (Y2O3)?????? ?????? ?????? X Index. décimale : 530 Physique Résumé : Preparation and structural and optical characterization of semiconductor nanocrystals of Sb2O3 and Y2O3 oxide dispersed in a crystalline matrices of alkali halides KBr, KCl and NaCl. In this work antimony oxide (Sb2O3) and yttrium oxide (Y2O3) nanocrystals doped KBr, KCl and NaCl single crystals have been grown by Czochralski (Cz) method. The effects of doping on the structural and optical properties of the host matrices have been studied. The structural studies of samples were performed by XRD, μ-Raman, IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The treatment of XRD spectrum confirms the existence of crystallites of dopants (Sb2O3 and Y2O3) in the nanometer regime; on the other hand, the existence of the stable monoclinic phase crystallites (Y2O3) under atmospheric conditions reconfirms presence of (Y2O3) in nanoscale. Studies by μ-Raman and IR confirmed the presence of chemical bonds Y—O and Sb—O in the different matrices. The morphological study using the scanning electron microscope (SEM) shows that the micron grains scattered on the surface. The volume of these aggregates is due to the fact that the nanocrystals have a tendency to reduce its free energy (Gibbs energy) of surface. The optical absorption and photoluminescence shows that the optical gaps of the crystallites (Sb2O3 and Y2O3) have been shifted to the high energy due to the quantum confinement effect of the charges. The samples have important intense luminescence properties in the ultraviolet range. This feature makes these materials candidates which might come in the manufacture of components for optical systems using shorter wavelengths. Diplôme : Doctorat en sciences En ligne : ../theses/physique/BOU6378.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9379

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