<p>Coordination compounds of europium and titanium with oxide, ethoxide (OCH₂CH₃), <em>iso</em>-propoxide (OCH(CH₃)₂) and <em>tert</em>-butoxide (OC(CH₃)₃) ligands have been studied. These belong to the general class of oxo-alkoxides, M<em>_x</em>O<em>_y</em>(OR)<em>_z</em>, with alkoxide ligands (OR) containing an organic, aliphatic part R. The R group can be systematically varied, permitting the investigation of the influence of electronic and steric effects on the coordination of metal and oxygen atoms. Their tendency towards hydrolysis and formation of metal-oxygen-metal bridges also makes (oxo)alkoxides interesting as precursors in liquid solution-based or gas phase-based synthesis of many technologically important materials.</p><p>The structure of a termetallic oxo-alkoxide of formula Eu₃K₃TiO₂(OH/OCH₃)(OR)₁₁(HOR) (R = C(CH₃)₃) was revealed by a combination of single-crystal X-ray diffraction and IR spectroscopy. Its unusual structure features a facial oxygen-centered Eu₃K₃O octahedron sharing one face with an oxygen-centered K₃TiO tetrahedron. Six-coordination of oxygen by a combination of alkali metal and lanthanoid atoms is not uncommon for alkoxides, but the attachment of a tetrahedron to one of its faces provides a new dimension to the library of oxo-alkoxide structures. The structure was the result of incomplete metathesis in the synthesis attempt of europium-titanium oxo-<em>tert</em>-butoxides.</p><p>Eu₄TiO(OR)₁₄ and (Eu_0.5La_0.5)₄TiO(OR)₁₄ (R = CH(CH₃)₂) were found to be isostructural with previously published Ln₄TiO(OR)₁₄ structures (Ln=Sm, Tb_0.9Er_0.1). X-ray diffraction and UV-Vis absorption results show no site preference for La in either the solid state or hexane solution. The Ln₄TiO(OR)₁₄ structure forms part of an interesting group of Ln₄MO(OR)_{10+<em>z</em>}<em>­</em>(HOR)<em>_q</em> structures where M is another lanthanoid (Ln) or a di-, tri- or tetravalent heteroatom, giving either a square pyramidal or a trigonal bipyramid-like coordination of the central oxygen atom, depending on the chemistry and size of M.</p><p>Eu₂Ti₄O₂(OR)₁₈(HOR)₂ (R = CH₂CH₃) was deduced from IR data to have the same molecular structure as Er₂Ti₄O₂(OR)₁₈(HOR)₂. UV-Vis measurements are also in agreement with the presence of one symmetry-unique europium site in the molecular structure. Structure determination by single-crystal X-ray diffraction has yet to be performed.</p><p> </p><p>Coordination compounds of europium and titanium with oxide, ethoxide (OCH2CH3), isopropoxide(OCH(CH3)2) and tert-butoxide (OC(CH3)3) ligands have been studied. Thesebelong to the general class of oxo-alkoxides, MxOy(OR)z, with alkoxide ligands (OR)containing an organic, aliphatic part R. The R group can be systematically varied, permittingthe investigation of the influence of electronic and steric effects on the coordination of metaland oxygen atoms. Their tendency towards hydrolysis and formation of metal-oxygen-metalbridges also makes (oxo)alkoxides interesting as precursors in liquid solution-based or gasphase-based synthesis of many technologically important materials.The structure of a termetallic oxo-alkoxide of formula Eu3K3TiO2(OH/OCH3)(OR)11(HOR)(R = C(CH3)3) was revealed by a combination of single-crystal X-ray diffraction and IRspectroscopy. Its unusual structure features a facial oxygen-centered Eu3K3O octahedronsharing one face with an oxygen-centered K3TiO tetrahedron. Six-coordination of oxygen bya combination of alkali metal and lanthanoid atoms is not uncommon for alkoxides, but theattachment of a tetrahedron to one of its faces provides a new dimension to the library of oxoalkoxidestructures. The structure was the result of incomplete metathesis in the synthesisattempt of europium-titanium oxo-tert-butoxides.Eu4TiO(OR)14 and (Eu0.5La0.5)4TiO(OR)14 (R = CH(CH3)2) were found to be isostructuralwith previously published Ln4TiO(OR)14 structures (Ln=Sm, Tb0.9Er0.1). X-ray diffraction andUV-Vis absorption results show no site preference for La in either the solid state or hexanesolution. The Ln4TiO(OR)14 structure forms part of an interesting group of Ln4MO(OR)10+z-(HOR)q structures where M is another lanthanoid (Ln) or a di-, tri- or tetravalent heteroatom,giving either a square pyramidal or a trigonal bipyramid-like coordination of the centraloxygen atom, depending on the chemistry and size of M.Eu2Ti4O2(OR)18(HOR)2 (R = CH2CH3) was deduced from IR data to have the samemolecular structure as Er2Ti4O2(OR)18(HOR)2. UV-Vis measurements are also in agreementwith the presence of one symmetry-unique europium site in the molecular structure. Structuredetermination by single-crystal X-ray diffraction has yet to be performed.</p>

Coordination compounds of europium and titanium with oxide, ethoxide (OCH2CH3), iso-propoxide (OCH(CH3)2) and tert-butoxide (OC(CH3)3) ligands have been studied. These belong to the general class of oxo-alkoxides, MxOy(OR)z, with alkoxide ligands (OR) containing an organic, aliphatic part R. The R group can be systematically varied, permitting the investigation of the influence of electronic and steric effects on the coordination of metal and oxygen atoms. Their tendency towards hydrolysis and formation of metal-oxygen-metal bridges also makes (oxo)alkoxides interesting as precursors in liquid solution-based or gas phase-based synthesis of many technologically important materials. The structure of a termetallic oxo-alkoxide of formula Eu3K3TiO2(OH/OCH3)(OR)11(HOR) (R = C(CH3)3) was revealed by a combination of single-crystal X-ray diffraction and IR spectroscopy. Its unusual structure features a facial oxygen-centered Eu3K3O octahedron sharing one face with an oxygen-centered K3TiO tetrahedron. Six-coordination of oxygen by a combination of alkali metal and lanthanoid atoms is not uncommon for alkoxides, but the attachment of a tetrahedron to one of its faces provides a new dimension to the library of oxo-alkoxide structures. The structure was the result of incomplete metathesis in the synthesis attempt of europium-titanium oxo-tert-butoxides. Eu4TiO(OR)14 and (Eu0.5La0.5)4TiO(OR)14 (R = CH(CH3)2) were found to be isostructural with previously published Ln4TiO(OR)14 structures (Ln=Sm, Tb0.9Er0.1). X-ray diffraction and UV-Vis absorption results show no site preference for La in either the solid state or hexane solution. The Ln4TiO(OR)14 structure forms part of an interesting group of Ln4MO(OR)10+z­(HOR)q structures where M is another lanthanoid (Ln) or a di-, tri- or tetravalent heteroatom, giving either a square pyramidal or a trigonal bipyramid-like coordination of the central oxygen atom, depending on the chemistry and size of M. Eu2Ti4O2(OR)18(HOR)2 (R = CH2CH3) was deduced from IR data to have the same molecular structure as Er2Ti4O2(OR)18(HOR)2. UV-Vis measurements are also in agreement with the presence of one symmetry-unique europium site in the molecular structure. Structure determination by single-crystal X-ray diffraction has yet to be performed.   Coordination compounds of europium and titanium with oxide, ethoxide (OCH2CH3), isopropoxide(OCH(CH3)2) and tert-butoxide (OC(CH3)3) ligands have been studied. Thesebelong to the general class of oxo-alkoxides, MxOy(OR)z, with alkoxide ligands (OR)containing an organic, aliphatic part R. The R group can be systematically varied, permittingthe investigation of the influence of electronic and steric effects on the coordination of metaland oxygen atoms. Their tendency towards hydrolysis and formation of metal-oxygen-metalbridges also makes (oxo)alkoxides interesting as precursors in liquid solution-based or gasphase-based synthesis of many technologically important materials.The structure of a termetallic oxo-alkoxide of formula Eu3K3TiO2(OH/OCH3)(OR)11(HOR)(R = C(CH3)3) was revealed by a combination of single-crystal X-ray diffraction and IRspectroscopy. Its unusual structure features a facial oxygen-centered Eu3K3O octahedronsharing one face with an oxygen-centered K3TiO tetrahedron. Six-coordination of oxygen bya combination of alkali metal and lanthanoid atoms is not uncommon for alkoxides, but theattachment of a tetrahedron to one of its faces provides a new dimension to the library of oxoalkoxidestructures. The structure was the result of incomplete metathesis in the synthesisattempt of europium-titanium oxo-tert-butoxides.Eu4TiO(OR)14 and (Eu0.5La0.5)4TiO(OR)14 (R = CH(CH3)2) were found to be isostructuralwith previously published Ln4TiO(OR)14 structures (Ln=Sm, Tb0.9Er0.1). X-ray diffraction andUV-Vis absorption results show no site preference for La in either the solid state or hexanesolution. The Ln4TiO(OR)14 structure forms part of an interesting group of Ln4MO(OR)10+z-(HOR)q structures where M is another lanthanoid (Ln) or a di-, tri- or tetravalent heteroatom,giving either a square pyramidal or a trigonal bipyramid-like coordination of the centraloxygen atom, depending on the chemistry and size of M.Eu2Ti4O2(OR)18(HOR)2 (R = CH2CH3) was deduced from IR data to have the samemolecular structure as Er2Ti4O2(OR)18(HOR)2. UV-Vis measurements are also in agreementwith the presence of one symmetry-unique europium site in the molecular structure. Structuredetermination by single-crystal X-ray diffraction has yet to be performed.

A dual neutron and gamma detection system has been developed for online measurements. The system consists of a single crystal mounted on a photomultiplier tube to detect simultaneously gamma radiation as well as thermal neutrons. A compact data acquisition system has been used for neutron and gamma discrimination. The system has been tested with different gamma energies and with an Am-Be neutron source at the University of Ontario Institute of Technology neutron facility. This thesis presents the characteristics of the developed detector, and experimental data carried out in different experiments in different fields. / UOIT

En vue d'application à l'éclairage ou dans les dispositifs de visualisation à plama, on a étudié la luminescence de l'ion Eu2+ dans les borates BaLnB9O16 (Ln = La, Ce, Gd, Y) et de l'ion Eu3+ dans les diverses phases des systèmes Gd2O3-P2O5 et Y2O3-P2O5. Des informations sur les structures des réseaux-hôtes lorsqu'elles étaient inconnues, ont pu être obtenues par diffraction X et spectroscopie Raman. Pour Ln = Y, Gd, les borates BaLnB9O16:Eu2+ présentent une émission dans le bleu stable...

comme luminophore rouge dans les nouveaux dispositifs de visualisation à panneaux plasma ; le borate Li6(Y,Gd)(BO3)3: Ce3+ est particulièrement approprié pour la détection des neutrons. Outre les borates Li6Ln(BO3)3 (Ln = terre rare) et Li3Ln2(BO3)3 antérieurement connus, l'étude des diagrammes ternaires Li2O-B2O3-Ln2O3 a mis en évidence l'existence de quatre autres compositions : les borates Li3Ln(BO3)2 et les oxyborates LiLn6O5(BO3)3, LiLn2O2BO3 et<br />Li2Ln5O4(BO3)3. Chacune des structures a été résolue sur monocristal par diffraction des rayons X.<br />Une caractéristique des oxyborates est l'existence d'un assemblage de tétraèdres OLn4, tridimensionnel<br />dans les borates LiLn6O5(BO3)3 , bidimensionnel dans les phases Li2Ln5O4(BO3)3 et LiLn2O2BO3 , les groupes (BO3)3- et les ions Li+ se disposent dans des cavités ou entre les couches de ces sous-réseaux. Une étude de la luminescence des ions Eu3+, Tm3+ et Ce3+ a été effectuée afin notamment d'évaluer les performances de ces nouveaux matériaux en tant que luminophores ou scintillateurs. Pour la première fois dans des composés du bore, une luminescence de transfert de charge du lanthane et du cérium tétravalent a par ailleurs été observée.

Compositionally related glasses and ceramics of the Na$ sb2$O$ cdot$CaO$ cdot$Al$ sb2$O$ sb3 cdot$TiO$ sb2 cdot$SiO$ sb2$ system (sphene glass-ceramics) doped with Eu$ sp{3+}$ were examined using site-selective spectroscopic techniques (FLN). In sphene glass-ceramics, Eu$ sp{3+}$ preferentially partitions into the crystalline sphene phase. The partition ratio is concentration dependent, decreasing at higher concentrations, because of the limited solid solubility of Eu$ sp{3+}$ in sphene. The concentration occurs at the time of phase separation; Eu$ sp{3+}$ preferentially enters the more ionic (CaO, TiO$ sb2$)- rich droplet phase which eventually becomes sphene. In sphene, Eu$ sp{3+}$ substitutes for Ca$ sp{2+}$ appearing in three different sites caused by associated charge compensation defects. From an analysis of the FLN spectra of the different glasses, the framework for a model describing the coordination shell of Eu$ sp{3+}$ in oxide glasses is developed. The model suggests that Eu$ sp{3+}$ behaves as a network forming ion or quasi-molecular complex. The model is used to explain qualitative features of Eu$ sp{3+}$ FLN spectra including the dependence of the clustering of points of the major crystal field parameter ratios plot on the relative number of non-bridging oxygen ions and Eu$ sp{3+}$ ions in the glass.

Ce travail étudie le potentiel de l'électrophorèse capillaire couplée à la spectrométrie de masse à ionisation par plasma (ICP/MS) pour le criblage d'une bibliothèque de ligands en fonction de leur affinité pour l'europium en milieu hydro-organique. Cette méthode permet, d'une part, d'évaluer l'affinité des ligands phosphorés en moins de deux heures et en utilisant moins de 15 ng de ligand, et d'autre part, de déterminer les constantes de complexation. Les résultats sont en accord avec ceux obtenus par titrage spectrophotométrique.Parallèlement, une bibliothèque de copolymères pour l'extraction solide/liquide de l'europium a été étudiée. Le protocole d'extraction mis au point permet de les classer selon leur affinité pour celui-ci en milieu hydro-organique et en utilisant 60 mg de copolymère. Pour les plus prometteurs, les propriétés de reconnaissance et la sélectivité La3+/Eu3+/Lu3+ ont été évaluées.

Nuo 1926-ųjų metų, kai pirmą kartą buvo ištirta preliminari natūralių silikatinių mineralų, turinčių kubinę kristalinę gardelę, struktūra, granatų šeimai priskiriami junginiai tapo viena labiausiai tyrinėjamų medžiagų grupių. Granatai, kuriuose yra pereinamųjų metalų bei retųjų žemių metalų, pasižymi ypatingu technologiniu pritaikymu. Kaip šviečiančios medžiagos jie naudojami kietafaziuose lazeriuose, televizorių ekranuose ar dioduose. Europiu arba chromu legiruoti junginiai galėtų būti pritaikyti optiniam vaizdavimui medicinoje, kas iki šiol nebuvo daryta. Galimybė pagerinti granatų optines ir mechanines savybes bei naujos pritaikymo sritys suteikia stiprią motyvaciją tyrinėjimams. Pagrindinis disertacijos tikslas buvo naujų mišrių metalų granatų sintezė bei jų optinių savybių tyrimas. Taip pat siekta ištirti europį supančios aplinkos įtaką jo liuminescencinėms savybėms tiek milteliuose, tiek kristaluose. Milteliai buvo sintetinti zolių-gelių arba kietafazės reakcijos metodu. Kristalai auginti keliaujančio lydalo slankioje zonoje būdu. Medžiagų faziniai virsmai tirti Rentgeno spindulių difrakcijos metodu. Neutronų difrakcijos duomenys bei Rietveldo tikslinimas buvo panaudoti granatų struktūrinei analizei. Junginių optinės savybės įvertintos išmatavus atspindžio, sužadinimo ir emisijos spektrus. / Since 1926 when the preliminary structure of natural silicate minerals having cubic structure was determined, the family of garnets became one of the most extensively studied group of compounds. Garnets containing transition metals and rare-earths carry many important technological uses as magnetic materials, as phosphor materials employed in solid state lasers, television screens and light-emitting diodes, as computer memories, as near UV and near IR radiation up/down-converting compounds in Si solar cells and in other devices as microwave optical elements. The europium or chromium doped garnets also could be applied in the new field as optical imaging. The improvements in mechanical and optical properties, the new areas of applications provide a strong motivation for studying garnets in general. To synthesize and to characterize new mixed-metal garnets was the main aim of the present thesis. The investigation of the dependence of europium optical properties on the local environment in different garnets was also in the field of interest. Therefore, powders of the new mixed-metal garnets were synthesized by sol-gel route, while traveling solvent floating zone method was used for crystal growth. X-ray diffraction was used for phase identification. The neutrons diffractions and Rietveld refinement gave information of the crystal structure. Finally, reflection, excitation and emission spectra were recorded for the investigation of the optical properties.

Since 1926 when the preliminary structure of natural silicate minerals having cubic structure was determined, the family of garnets became one of the most extensively studied group of compounds. Garnets containing transition metals and rare-earths carry many important technological uses as magnetic materials, as phosphor materials employed in solid state lasers, television screens and light-emitting diodes, as computer memories, as near UV and near IR radiation up/down-converting compounds in Si solar cells and in other devices as microwave optical elements. The europium or chromium doped garnets also could be applied in the new field as optical imaging. The improvements in mechanical and optical properties, the new areas of applications provide a strong motivation for studying garnets in general. To synthesize and to characterize new mixed-metal garnets was the main aim of the present thesis. The investigation of the dependence of europium optical properties on the local environment in different garnets was also in the field of interest. Therefore, powders of the new mixed-metal garnets were synthesized by sol-gel route, while traveling solvent floating zone method was used for crystal growth. X-ray diffraction was used for phase identification. The neutrons diffractions and Rietveld refinement gave information of the crystal structure. Finally, reflection, excitation and emission spectra were recorded for the investigation of the optical properties. / Nuo 1926-ųjų metų, kai pirmą kartą buvo ištirta preliminari natūralių silikatinių mineralų, turinčių kubinę kristalinę gardelę, struktūra, granatų šeimai priskiriami junginiai tapo viena labiausiai tyrinėjamų medžiagų grupių. Granatai, kuriuose yra pereinamųjų metalų bei retųjų žemių metalų, pasižymi ypatingu technologiniu pritaikymu. Kaip šviečiančios medžiagos jie naudojami kietafaziuose lazeriuose, televizorių ekranuose ar dioduose. Europiu arba chromu legiruoti junginiai galėtų būti pritaikyti optiniam vaizdavimui medicinoje, kas iki šiol nebuvo daryta. Galimybė pagerinti granatų optines ir mechanines savybes bei naujos pritaikymo sritys suteikia stiprią motyvaciją tyrinėjimams. Pagrindinis disertacijos tikslas buvo naujų mišrių metalų granatų sintezė bei jų optinių savybių tyrimas. Taip pat siekta ištirti europį supančios aplinkos įtaką jo liuminescencinėms savybėms tiek milteliuose, tiek kristaluose. Milteliai buvo sintetinti zolių-gelių arba kietafazės reakcijos metodu. Kristalai auginti keliaujančio lydalo slankioje zonoje būdu. Medžiagų faziniai virsmai tirti Rentgeno spindulių difrakcijos metodu. Neutronų difrakcijos duomenys bei Rietveldo tikslinimas buvo panaudoti granatų struktūrinei analizei. Junginių optinės savybės įvertintos išmatavus atspindžio, sužadinimo ir emisijos spektrus.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.