RESUMEN
The present work reports the study of the thermally coupled energy levels of the trivalent europium ion in the barium hafnate matrix, in the temperature range of 289.7-323.8 K, through the application of ultraviolet radiation. Barium hafnate doped with 1, 3, and 5 atomic % trivalent europium ion was synthesized by the hydrothermal route, using chlorides as precursor elements. X-ray diffraction analysis indicates that the material crystallized in the perovskite cubic phase of barium hafnate, according to diffraction card file number #24-0102. Using high-resolution transmission electron microscopy, it was observed that the obtained crystals have an average size of 10 nm. From the photoluminescent analysis at room temperature, it was found that the sample doped with 3.0% atomic of trivalent europium displayed with the highest luminescent emission, while the photoluminescent analysis as a function of temperature showed that the bands associated with the 5D0 â 7FJ (J = 1,2,3,4) transitions have a strong dependence on temperature in the physical range.
RESUMEN
This article presents the synthesis, characterization and spectroscopic study of silica modified with thenoyltrifluoroacetonate (SilTTA) and coordinated to an europium (III) ion, for the determination of sialic acid (NANA). Elemental analysis and infrared spectroscopy suggest silica functionalization, as well as coordination of beta-diketone to the lanthanide ion. The emission spectra of compound-free and coordinated Eu-SilTTA to NANA showed significant changes with respect to the maximum emission and spectral profile, suggesting that the NANA ion is coordinated to the Eu(III). The values of the phenomenological intensity parameters show an increase in polarizability around the Eu(III) in the case of Eu-SilTTA coordinated to NANA, as expected, since water molecules are less polarizable than sialic acid. The results of the batch assay showed that luminescent silica can be used for sialic acid determination in milk-adulterated samples, with a correlation coefficient of 0.9992; and a detection limit of 0.4 mg/L; relative standard deviation (RSD%) = 0.0028.