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Fernando Aparecido Sigoli - One of the best experts on this subject based on the ideXlab platform.
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Particle size tailoring and luminescence of Europium(III)-doped gadolinium oxide obtained by the modified homogeneous precipitation method: Dielectric constant and counter anion effects
Holanda, 2015Co-Authors: Gaspar Rdl, Italo Odone Mazali, Fernando Aparecido SigoliAbstract:Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This work reports on controlling the particle size distribution of Europium(III)-doped gadolinium oxide samples prepared through a topochemical reaction carried out by thermal treatment of Europium(III)-doped gadolinium hydroxycarbonate. Hydroxycarbonate samples were obtained by a modified homogeneous precipitation method using different solvent mixtures, such as water:ethanol, water:ethylene glycol, water:tert-butanol, and different counter ions such as nitrate and chloride. The luminescent properties of the oxide samples, are characteristics of Europium(III) ions, with the hypersensitive transition ((5)D(0) --> (7)F(2)) being the most intense emission peak and the emission lifetime values are typical for this system. The spherical particle size distribution of Europium(III)-doped gadolinium oxide can be tailored by selecting the counter anion types, the chemical nature of the alcohol and the dielectric constant of the reaction media. The appropriate control of these parameters allows the preparation of rare-earth doped gadolinium samples having monomodal particle size distributions with mean sizes between 30 and 90 nanometers. (C) 2010 Elsevier B.V. All rights reserved.36741699155160Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
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particle size tailoring and luminescence of Europium iii doped gadolinium oxide obtained by the modified homogeneous precipitation method dielectric constant and counter anion effects
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010Co-Authors: Rafael D L Gaspar, Italo Odone Mazali, Fernando Aparecido SigoliAbstract:Abstract This work reports on controlling the particle size distribution of Europium(III)-doped gadolinium oxide samples prepared through a topochemical reaction carried out by thermal treatment of Europium(III)-doped gadolinium hydroxycarbonate. Hydroxycarbonate samples were obtained by a modified homogeneous precipitation method using different solvent mixtures, such as water:ethanol, water:ethylene glycol, water:tert-butanol, and different counter ions such as nitrate and chloride. The luminescent properties of the oxide samples, are characteristics of Europium(III) ions, with the hypersensitive transition (5D0 → 7F2) being the most intense emission peak and the emission lifetime values are typical for this system. The spherical particle size distribution of Europium(III)-doped gadolinium oxide can be tailored by selecting the counter anion types, the chemical nature of the alcohol and the dielectric constant of the reaction media. The appropriate control of these parameters allows the preparation of rare-earth doped gadolinium samples having monomodal particle size distributions with mean sizes between 30 and 90 nanometers.
Joseph W Ziller - One of the best experts on this subject based on the ideXlab platform.
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direct synthesis of heterometallic Europium barium complexes h2 eu2ba6o2 oipr 16 thf 4 and euba2 oc6h4me 4 7 diglyme 2 dme
European Journal of Inorganic Chemistry, 2002Co-Authors: William J Evans, Michael A Greci, Dimitrios G Giarikos, Joseph W ZillerAbstract:Convenient syntheses of mixed-metal Eu/Ba complexes starting from the elemental metals have been explored. A mixture of Europium and barium ingots reacts in boiling 2-propanol to form a product which crystallizes from THF as the heterometallic complex formulated as H2[Eu2Ba6O2(OiPr)16(THF)4] (1). An analogous reaction in the presence of p-cresol (HOC6H4Me-4) forms trimetallic EuBa2(OC6H4Me4)7(diglyme)2(DME) (2), after recrystallization from THF/DME/diglyme (DME = 1,2-dimethoxyethane). Complex 1 exhibits an octametallic geometry comprised of two square pyramids with coplanar bases which share a basal edge and have apices on opposite sides. The six barium atoms occupy the basal positions and the two Europium atoms are at the apices. Complex 2 exhibits a triangular arrangement of metal atoms with both terminal and bridging aryloxide ligands coordinated to the Europium atom and bridging aryloxide and terminal ether ligands coordinated to the barium atoms.
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utility of 2 methoxyethanol in the synthesis of polyEuropium complexes l_brace eu och sub 2 ch sub 2 ome sub 2 oc sub 6 h sub 3 r sub 2 2 6 sup minus h sup r_brace sub 4 r me sup i pr and eual sub 2 och sub 2 ch sub 2 ome sub 3 me sub 5 sub 2
Inorganic Chemistry, 1998Co-Authors: William J Evans, Michael A Greci, Joseph W ZillerAbstract:Europium reacts with 2-methoxyethanol at room temperature to form arene-soluble [Eu(OCH{sub 2}CH{sub 2}OMe){sub 2}]n. 1. Reaction of 1 with 2,6-dimethylphenol or 2,6-diisopropylphenol forms the tetrametallic complexes {l_brace}[Eu({mu}{sub 3}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)({eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)(OC{sub 6}H{sub 3}R{sub 2}-2,6){sup {minus}}][H{sup +}]{r_brace}{sub 4} (R = Me, 2; R = {sup i}Pr, 3). Magnetic measurements of 1--3 in solution are consistent with the presence of divalent Europium. 2 and 3 are isostructural and contain a tetrahedral arrangement of Europium atoms. Coordinated to each seven-coordinate metal are one terminal bidentate alkoxide, one bridging bidentate alkoxide, which bridges through its alkoxide oxygen to two other Europium atoms, a terminal aryloxide, and two bridging oxygen atoms from other such units. The presence of protons in 2 was probed by reaction with Al{sub 2}Me{sub 6}, which forms hexametallic [Me{sub 3}Al({mu}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)Eu({mu}-{eta}{sup 2}-OCH{sub 2}-CH{sub 2}OMe){sub 2}AlMe{sub 2}]{sub 2}, 4. Each six-coordinate Europium in 4 is surrounded by three bidentate 2-methoxyethoxide ligands, which bridge via their alkoxide oxygen atoms. One ligand bridges to one AlMe{sub 3} unit, and the other two ligands bridge to AlMe{sub 2} units.
Joseph Georges - One of the best experts on this subject based on the ideXlab platform.
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fluorimetric determination of Europium over a large dynamic range using its ternary complex with thenoyltrifluoroacetone and trioctylphosphine oxide in a micellar solution of triton x 100
Analyst, 1997Co-Authors: Nadine Arnaud, Joseph GeorgesAbstract:The composition of the Europium–thenoyltrifluoroacetone (TTA)–trioctylphosphine (TOPO) chelate in water in the presence of Triton X-100 was investigated. The stoichiometric composition was found to be Eu(TTA) 3 (TOPO) 2 , but different compositions can occur depending on the relative concentrations of the ligands. The fluorescence properties of the ternary complex were examined and optimum experimental conditions were defined for the determination of Europium over a wide range of concentrations. The fluorescence intensity was a linear function of Europium concentration over six decades extending from 10 - 11 to 10 - 5 mol l - 1 with a detection limit of 6 × 10 - 12 mol l - 1 .
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investigation of fluorescence efficiency in the Europium thenoyltrifluoroacetone chelate in aqueous and ethanolic solutions by laser induced fluorescence and photothermal spectroscopic methods
Analytica Chimica Acta, 1995Co-Authors: Joseph GeorgesAbstract:Abstract The photophysical characteristics of the Europium (III)-thenoyltrifluoroacetone chelate were studied in a micellar Triton X-100 aqueous solution and in ethanol in correlation with the strong Europium-sensitized fluorescence observed in these media. The properties of the chelate and the resulting ion fluorescence intensity were first compared by steady-state absorbance and fluorescence experiments. Fluorescence lifetimes, fluorescence quantum yields and energy transfer efficiencies were then investigated using time-resolved fluorescence and thermal lens measurements. In ethanol with 10−2 M acetate buffer, the strong luminescence of Europium represents only some percent of the energy absorbed by the chelate and the efficiency of energy transfer from the ligand to the ion is calculated to be 0.165. In the aqueous micellar solution, the part of radiative energy is still smaller and cannot be measured by the thermal lens method. However, the analytical sensitivity is quite comparable because the absorption spectra of the ligand and the chelate are well separate and the lifetime of the lowest excited state 5Do of Europium(III) is made longer by the micellar environment.
Rafael D L Gaspar - One of the best experts on this subject based on the ideXlab platform.
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particle size tailoring and luminescence of Europium iii doped gadolinium oxide obtained by the modified homogeneous precipitation method dielectric constant and counter anion effects
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010Co-Authors: Rafael D L Gaspar, Italo Odone Mazali, Fernando Aparecido SigoliAbstract:Abstract This work reports on controlling the particle size distribution of Europium(III)-doped gadolinium oxide samples prepared through a topochemical reaction carried out by thermal treatment of Europium(III)-doped gadolinium hydroxycarbonate. Hydroxycarbonate samples were obtained by a modified homogeneous precipitation method using different solvent mixtures, such as water:ethanol, water:ethylene glycol, water:tert-butanol, and different counter ions such as nitrate and chloride. The luminescent properties of the oxide samples, are characteristics of Europium(III) ions, with the hypersensitive transition (5D0 → 7F2) being the most intense emission peak and the emission lifetime values are typical for this system. The spherical particle size distribution of Europium(III)-doped gadolinium oxide can be tailored by selecting the counter anion types, the chemical nature of the alcohol and the dielectric constant of the reaction media. The appropriate control of these parameters allows the preparation of rare-earth doped gadolinium samples having monomodal particle size distributions with mean sizes between 30 and 90 nanometers.
William J Evans - One of the best experts on this subject based on the ideXlab platform.
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direct synthesis of heterometallic Europium barium complexes h2 eu2ba6o2 oipr 16 thf 4 and euba2 oc6h4me 4 7 diglyme 2 dme
European Journal of Inorganic Chemistry, 2002Co-Authors: William J Evans, Michael A Greci, Dimitrios G Giarikos, Joseph W ZillerAbstract:Convenient syntheses of mixed-metal Eu/Ba complexes starting from the elemental metals have been explored. A mixture of Europium and barium ingots reacts in boiling 2-propanol to form a product which crystallizes from THF as the heterometallic complex formulated as H2[Eu2Ba6O2(OiPr)16(THF)4] (1). An analogous reaction in the presence of p-cresol (HOC6H4Me-4) forms trimetallic EuBa2(OC6H4Me4)7(diglyme)2(DME) (2), after recrystallization from THF/DME/diglyme (DME = 1,2-dimethoxyethane). Complex 1 exhibits an octametallic geometry comprised of two square pyramids with coplanar bases which share a basal edge and have apices on opposite sides. The six barium atoms occupy the basal positions and the two Europium atoms are at the apices. Complex 2 exhibits a triangular arrangement of metal atoms with both terminal and bridging aryloxide ligands coordinated to the Europium atom and bridging aryloxide and terminal ether ligands coordinated to the barium atoms.
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utility of 2 methoxyethanol in the synthesis of polyEuropium complexes l_brace eu och sub 2 ch sub 2 ome sub 2 oc sub 6 h sub 3 r sub 2 2 6 sup minus h sup r_brace sub 4 r me sup i pr and eual sub 2 och sub 2 ch sub 2 ome sub 3 me sub 5 sub 2
Inorganic Chemistry, 1998Co-Authors: William J Evans, Michael A Greci, Joseph W ZillerAbstract:Europium reacts with 2-methoxyethanol at room temperature to form arene-soluble [Eu(OCH{sub 2}CH{sub 2}OMe){sub 2}]n. 1. Reaction of 1 with 2,6-dimethylphenol or 2,6-diisopropylphenol forms the tetrametallic complexes {l_brace}[Eu({mu}{sub 3}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)({eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)(OC{sub 6}H{sub 3}R{sub 2}-2,6){sup {minus}}][H{sup +}]{r_brace}{sub 4} (R = Me, 2; R = {sup i}Pr, 3). Magnetic measurements of 1--3 in solution are consistent with the presence of divalent Europium. 2 and 3 are isostructural and contain a tetrahedral arrangement of Europium atoms. Coordinated to each seven-coordinate metal are one terminal bidentate alkoxide, one bridging bidentate alkoxide, which bridges through its alkoxide oxygen to two other Europium atoms, a terminal aryloxide, and two bridging oxygen atoms from other such units. The presence of protons in 2 was probed by reaction with Al{sub 2}Me{sub 6}, which forms hexametallic [Me{sub 3}Al({mu}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)Eu({mu}-{eta}{sup 2}-OCH{sub 2}-CH{sub 2}OMe){sub 2}AlMe{sub 2}]{sub 2}, 4. Each six-coordinate Europium in 4 is surrounded by three bidentate 2-methoxyethoxide ligands, which bridge via their alkoxide oxygen atoms. One ligand bridges to one AlMe{sub 3} unit, and the other two ligands bridge to AlMe{sub 2} units.
