Structural and optical aspects for Eu3+ and Dy3+ ions in heavy metal glasses based on PbO–Ga2O3–XO2 (X = Te, Ge, Si)

Abstract

Structural and optical properties of Eu3+ and Dy3+ ions in PbO–Ga2O3–XO2 (X=Te, Ge, Si) glasses have been examined using X-ray diffraction, FT-IR and luminescence spectroscopy. Several crystalline phases such as TeO2, PbTe3O7, PbO and PbO2 were identified in lead tellurite system using X-ray diffraction analysis, in contrast to PbO–Ga2O3–XO2 (X=Ge, Si) glass samples. Characteristic emission bands due to the 5D0→7FJ (J=0–4) transitions of Eu3+ and the 4F9/2→6HJ/2 (J=15, 13, 11) transitions of Dy3+ were registered. Two spectroscopic parameters, such as luminescence intensity ratios associated to 5D0→7F2 and 5D0→7F1 transitions of Eu3+ as well as 4F9/2→6H13/2 and 4F9/2→6H15/2 transitions of Dy3+, and luminescence lifetimes for excited states of rare earth ions were determined. The luminescence intensity ratios for Eu3+ and Dy3+ ions decrease, whereas 5D0 (Eu3+) and 4F9/2 (Dy3+) luminescence lifetime increases, when covalence between Ln3+ and O2− ions is reduced and the phonon energy of the host glass is increased in PbO–TeO2→PbO–GeO2→PbO–SiO2 direction. It was confirmed by FT-IR measurements.