Impact of europium concentration on thermal and absorption features of amorphous tellurite media

Abstract

Improving the structural and optical properties of tellurite glasses via optimized doping of rare earth ions is an outstanding issue in materials science. Tellurite glasses doped with trivalent europium (Eu3+) are successfully prepared using conventional melt quenching technique. Glasses with chemical composition of (80-x)TeO2-10PbO-10ZnO-(x)Eu2O3 where 0 ≤ x ≤ 2.0 mol% are obtained. The influence of Eu3+ ions concentration on the thermal and absorption properties of the synthesized glasses is investigated using Differential Thermal Analyzer (DTA) and UV-VIS Spectroscopy. DTA curves in the temperature range of 50-1000 °C at a heating rate of 10 °C/min are used to determine the temperature of glass transition, crystallization, melting and in turn the thermal stability. DTA revealed that the increase in the Eu3+ contents improved the thermal stability. This observation is attributed to the alteration of the glass network structure via the creation of non-bridging oxygen. The room temperature absorption spectra recorded in the spectral region of 200 – 2000 nm exhibited three absorption peaks corresponding to 7F0 → 5D0, 7F0 → 5D1 and 7F0 → 5D2 transitions. The absorption intensity is found to be enhanced up to certain concentration of Eu3+ ions and then quenched. This is ascribed to the change in glass network structure and formation of defects through the cleavage of weak bonds and reduction in covalence states.