0000000000385206
AUTHOR
Dzidra Jankoviča
Photoluminescence and photocatalytic activity of zinc tungstate powders
Abstract ZnWO4 powders with grain size in range 20 nm–10 µm have been synthesized by a simple combustion method and subsequent calcinations. The photocatalytic activities of powders were tested by degradation of methylene blue solution under UV light. The luminescence spectra and luminescence decay kinetics were studied and luminescence decay time dependence on average powder-grain size was obtained. The correlation between self-trapped exciton luminescence decay time and photocatalytic activity of ZnWO4 powders was shown. A model explaining the excitonic luminescence decay time correlation with photocatalytic activity was proposed.
Up-conversion luminescence dependence on structure in zirconia nanocrystals
The zirconia samples containing two different concentrations of Er and Yb dopants were prepared using the Sol–Gel method and up-conversion luminescence was studied using the time-resolved techniques. The up-conversion luminescence depends on the oxygen content in surrounding gasses during annealing as well as on the annealing temperature. These dependencies indicate that ZrO2 intrinsic defects annealing and generation, phase transition as well as dopant redistribution take place. The possible role of these processes on up-conversion luminescence is discussed. The results of experiments confirmed that the annealing temperature has a crucial influence on up-conversion luminescence for samples…
Luminescence of Er/Yb and Tm/Yb doped FAp nanoparticles and ceramics
The nanoparticles of hydroxiapatite and fluorapatite doped with Er/Yb and Tm/Yb were synthesized and characterized by FTIR, XRD, SEM and TEM methods. The results of up-conversion luminescence studies were presented for the samples as prepared, annealed at 500°C and at 900-1000 °C. At annealing above 800°C the ceramic state was formed. It is shown that fluorapatite host is more appropriate than hydroxiapatite host for rare ions luminescence and up-conversion processes. The post preparing annealing of nanarticles significantly enhanced the luminescence intensity. The Tm/Yb doped fluorapatite shows intense up-conversion luminescence in 790-800 nm spectral region and is potentially useful for b…
Phase stability and oxygen-sensitive photoluminescence of ZrO2:Eu,Nb nanopowders
This work was supported by institutional research funding ( IUT34-27 and IUT2-14 ) of the Estonian Ministry of Education and Research .