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Journal of Thermal Analysis and Calorimetry
Authors: D. Melo, G. Vicentini, L. Zinner, K. Zinner, H. de Souza, M. Batista, A. Garrido Pedrosa, and R. Bezerra

Abstract  

Complexes of neodymium and europium with amides and aminoxides were synthesized and characterized by complexometric analyses with EDTA, CHN microanalytical procedures, IR absorption spectra, absorption spectra of neodymium complexes, emission spectrum of europium compounds at 77 K, thermogravimetric analyses in N2 and differential scanning calorimetry (DSC) in N2. Infrared spectroscopy results revealed that the nitrate molecules are bound to the central ions as bidentate. Thermogravimetric plots indicated that the decomposition of the complexes occurs in the range 363-1163 K and resulted in the formation of Ln2O3 residues.

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Abstract  

Complex formation of humic acids (HA)n with La3+ and Eu3+ was studied. Commercial (HA)n was purified and characterized. The stability constants were determined at several pH values and 0.2 M NaClO4 ionic strength by the Shubert’s method of radiochemical ionic exchange. The slopes of the lines
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\log ((\lambda_{0} /\lambda ) - 1) = \log \beta_{\text{M,j(HA)n}}^{\exp } + {\text{j}} * \log \left[ { ( {\text{HA)}}_{\text{n}} } \right]$$ \end{document}
were dependent on the [(HA)n]. The values of log
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\beta_{\text{M,j(HA)n}}^{\exp }$$ \end{document}
for j = 1 were the following: 6.29 ± 0.04 (pH 4.9 ± 0.4) and 7.61 ± 0.03 (pH 5.9 ± 0.1) for lanthanum and 7.31 ± 0.01 (pH 5.9 ± 0.2) for europium. Log
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\beta_{\text{M,j(HA)n}}^{\exp }$$ \end{document}
was determined as well for higher values of the j parameter and these values were: 12.2 ± 0.1 (j = 2, pH 7.7 ± 0.2), 15.6 ± 0.2 (j = 3, pH 4.9 ± 0.4) and 16.05 ± 0.07 (j = 3, pH 5.9 ± 0.1), for lanthanum and 13.18 ± 0.03 (j = 2, pH 5.9 ± 0.1) for europium. A discussion is presented about the complex formation regarding pH and [(HA)n].
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Abstract  

Polymers doped with rare earth complexes are advantaged in film production for many applications in the luminescent field. In this luminescent polycarbonate (PC) films doped with diaquatris(thenoyltrifluoroacetonate)europium(III) complex [Eu(TTA)3(H2O)2] were prepared and their calorimetric and luminescent properties in the solid state are reported. The thermal behavior was investigated by utilization of differential scanning calorimetry (DSC) and thermogravimetry (TG). Due of the addition of rare earth [Eu(TTA)3(H2O)2] into PC matrix, changes were observed in the thermal behavior concerning the glass transition and thermal stability. Characteristic broadened narrow bands arising from the 5D0 → 7FJ transitions (J = 4−0) of Eu3+ ion indicate the incorporation of the Eu3+ ions in the polymer. The luminescent films show enhancement emission intensity with an increase of rare earth concentration in polymeric matrix accompanied by decrease in thermal stability.

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Abstract  

The thermal behavior of[Eu2(BA)6(dmbpy)2] (BA=C7H5O 2 , benzoate; dmbpy=C12H12N2, 4,4-dimethyl-2,2-bipyridine) and its kinetics were studied under the non-isothermal condition in a static air atmosphere by TG-DTG, IR and SEM methods. Thermal decomposition of [Eu2(BA)6(dmbpy)2] occurred in four consecutive stages at T P 232, 360, 455 and 495°C. The kinetic parameters were obtained from analysis of the TG-DTG curves by Achar and Madhusudanan—Krishnan—Ninan (MKN) methods. The most probable mechanisms for the first stage was suggested by comparing the kinetics parameters.

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Abstract  

The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N 2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.

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Abstract  

New lanthanoid-iron complexes having phenanthlorine as the chelating ligand were synthesized and characterized by151Eu- and57Fe-Mössbauer spectroscopy. The temperature dependence of the area intensity of Mössbauer lines of europium complexes (single crystals) has been correlated to the state of molecular association in the solid state. The crystal structure of europium complex, {[Eu(phen)2(H2O)2][(μ-NC)2 Fe(CN)4]·2phen]}x was determined by X-ray crystal analysis. This complex consists of one-dimensional zig-zag chain structure.

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Abstract  

The effect of Aldrich humic acid (HA) on the mobility of137Cs,85Sr,152Eu and239Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation of cesium and even strontium in solutions — the neutral ligand interaction constants β (l/mol) are log β<−9.9 and 7.56±0.21 for Cs and Sr, respectively. The result for europium complexation in solution, log β=12.49±0.18 is in a good agreement with literature data. For plutonium(IV) not only a high proton competitive constant in solution was obtained, log β β=(−0.67±0.32)+3pH, but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants (
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24 l/g) of the elements with surface humic acid are 4.47±0.23, 4.39±0.08, and 6.40±0.33 for Cs, Sr, and Eu(III), respectively, and the logarithm of the proton competitive constant (
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24, l/g) for Pu(IV) −3.80±0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite were derived as logK d(AH)=−1.04±0.11, logK d(EuA)=1.56±0.11 and logK d(PuA)=2.25±0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH.
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CeO2-catalyzed ozonation of phenol

The role of cerium citrate as precursor of CeO2

Journal of Thermal Analysis and Calorimetry
Authors: M. F. Pinheiro da Silva, L. S. Soeira, K. R. P. Daghastanli, T. S. Martins, I. M. Cuccovia, R. S. Freire, and P. C. Isolani

polycarbonate (PC) doped with europium complex [Eu(TTA) 3 (H 2 O) 2 ] . J Therm Anal Calorim 97 : 497 – 502 10.1007/s10973-009-0327-6 . 4. Zhang , T , Chen , W , Ma , J , Qiang , Z 2008

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investigations of luminescent films polycarbonate (PC) doped with europium complex [Eu(TTA) 3 (H 2 O) 2 ] . J Therm Anal Calorim . 2009 ; 97 : 497 – 502 . 10.1007/s10973-009-0327-6 . 3. Gao , X

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