Correlated EPR and optical study of charge trapping phenomena in tellurite glasses. The role of barium oxide
Abstract
Tellurite glasses of the compositions TeO(2)(60%)-ZnO(40%) and TeO(2)(60%)-ZnO(20%)-BaO(20%) were prepared in the bulk form with following grinding into powders. The samples were X-ray irradiated.
The created charge trapping centers were studied in both types of samples using electron paramagnetic resonance (EPR) spectroscopy. The O(-) defect and two types of F(+) centers were discovered.
One of the F(+) center remained unchanged whereas the other one as well as the O(-) defect were affected by the presence of BaO. Moreover, photo-, radio- and thermoluminescence (PL, RL, TL, respectively) methods were applied as well.
The discovered charge trapping centers have been proven to influence luminescence properties as well - improving them in the TeO(2)(60%)-ZnO(40%) and vice versa degrading them in the TeO2(60%)-ZnO(20%)-BaO(20%) glasses. The effect was even stronger in the grinded samples as compared to the bulk ones.
The role of the BaO has been disclosed as supporting oxygen leakage from the host.