Vislielākais burtu izmērs
Lielāks burtu izmērs
Burtu standarta izmērs

LU CFI zinātniskais seminārs (15.03.2018.) Novel nanosized oxide materials for practical applications


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 Dr. Tamara Gavrilović (LU CFI) stāstīs par tēmu “Novel nanosized oxide materials for practical applications”.

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.