Photoluminescence of Europium(III) Dithiocarbamate Complexes: Electronic Structure, Charge Transfer and Energy Transfer
作者:Wagner M. Faustino、Oscar L. Malta、Ercules E. S. Teotonio、Hermi F. Brito、Alfredo M. Simas、Gilberto F. de Sá
DOI:10.1021/jp056180m
日期:2006.2.1
For the first time, we observed photoluminescence in Eu(III) dithiocarbamate complexes at room temperature-more specifically in [Eu(Et2NCS2)(3)phen], [Eu(Et2NCS2)(3)bpy] and the novel [Eu(Ph2NCS2)(3)phen], where phen stands for 1,10-phenanthroline and bpy for 2,2'-bipyridine. Correlations between the electronic structure of the dithiocarbamate ligands on one hand, and covalency, intensity, and ligand field spectroscopic parameters on the other, could be established. Moreover, the relative values of the emission quantum efficiencies obtained for these complexes, as well as their dependence with temperature, could be satisfactorily described by a theoretical methodology recently developed.
Synthesis and Magnetic Properties of Gd Doped EuS Nanocrystals with Enhanced Curie Temperatures
作者:Rachel S. Selinsky、Jae Hyo Han、Elvin A. Morales Pérez、Ilia A. Guzei、Song Jin
DOI:10.1021/ja104314c
日期:2010.11.17
EuS nanocrystals (NCs) were doped with Gd resulting in an enhancement of their magnetic properties. New EuS and GdS single source precursors (SSPs) were synthesized, characterized, and employed to synthesize Eu1-xGdxS NCs by decomposition in oleylamine and trioctylphosphine at 290 degrees C. The doped NCs were characterized using X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy, which support the uniform distribution of Gd dopants through electron energy loss spectroscopy (EELS) mapping. X-ray absorption spectroscopy (XAS) revealed the dopant ions in Eu1-xGdxS NCs to be predominantly Gd3+. NCs with a variety of doping ratios of Gd (0 <= x < 1) were systematically studied using vibrating sample magnetometry and the observed magnetic properties were correlated with the Gd doping levels (x) as quantified with ICP-AES. Enhancement of the Curie temperature (T-C) was observed for samples with low Gd concentrations (x <= 10%) with a maximum T-C of 29.4 K observed for NCs containing 5.3% Gd. Overall, the observed T-C, Weiss temperature (theta), and hysteretic behavior correspond directly to the doping level in Eu1-xGdxS NCs and the trends qualitatively follow those previously reported for bulk and thin film samples.