Latvijas Universitātes Cietvielu fizikas institūta, Doktorantūras skolas „Funkcionālie materiāli un nanotehnoloģijas” zinātniskais seminārs 15. martā plkst. 13:00, LU CFI, Ķengaraga ielā 8, 2.stāva zālē uzstājas Dr. Tamara Gavrilović (LU CFI).
The presentation will consist of on-going postdoctoral project updates which, by now, resulted in two scientific publications.
First research provides the detailed studies of (nano) particle's size effect on structural and luminescent properties of LaPO4:Eu3+synthesized by four different methods: high temperature solid-state, co-precipitation, reverse micelle and colloidal. It was found that the particle size has significant influence on the structure and luminescent properties of obtained nanomaterials. In particular, with a decrease in particle diameter emission bands broaden due to structural disorder and new emission bands from defect states appear in ultra-small (2 nm) nanoparticles. No concentration quenching of Eu3+ emission was observed with ultra-small nanoparticles (2 nm) and short nanorods (2 × 15 nm). Thus, these nanomaterials can be heavily doped with Eu, up to stoichiometric EuPO4. Critical distance for energy transfer between Eu3+ ions is about 18.2 Å and discloses the dipole-dipole interaction as the dominant mechanism for the emission quenching.
In second survey, we focused on syntheses, structure and spectroscopic properties of GdVO4:Dy3+ and DyVO4 (nano)particles. The size effect on the structure, and photoluminescence emission intensities was analyzed by X-ray diffraction, photoluminescence spectroscopy, scanning, transmission electron microscopy, and diffuse reflection spectroscopy. Photoluminescence spectra showed several bands in the visible and near-infrared regions which can be exclusively attributed to the f-f transitions of Dy3+ ions. Due to strong emission in the NIR spectral region, these luminescent GdVO4:Dy3+ and DyVO4 (bulk)particles incorporated in silica waveguides could find potential application for enhancement of 1.3 μm photoluminescence.