Nd3+ doped new oxyfluoro tellurite glasses and glass ceramics containing NaYF4 nano crystals − 1.06 µm emission analysis

Abstract

Oxyfluoro tellurite glasses with chemical composition TeO2-ZnO-YF3-NaF (TZYN), doped with Nd3+ in different concentrations were prepared by the melt-quenching technique. Judd–Ofelt analyses of Nd3+ ions in the precursor glasses were performed to evaluate the phenomenological intensity parameters Ω2,4,6. From the NIR emission spectra, characteristic parameters such as effective band with (∆λeff) and stimulated emission cross section (σP) were calculated for the three observed transitions, 4F3/2 → 4I9/2,4I11/2 and 4I13/2 and compared to other reported glasses. Based on the luminescence decay times of 4F3/2 excited state, the quantum efficiency was evaluated and it is highest for a 0.2 mol% Nd3+ doped glass (G-Nd2). Glass ceramics were obtained by controlled heat treatment of the glasses at 390 °C for 5 h (as determined by DSC), which is greater than the glass transition temperature Tg. Moreover, DSC results revealed that precipitation of the NdYF4 nanocrystalline phase (TC1) decreased with increasing Nd3+ concentration. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) investigations reveal that spherical NaYF4 nano-crystals are distributed homogeneously across the glassy matrix. The emission intensity of the 4F3/2→4I11/2 transition at 1.60 µm was enhanced in glass ceramics as compared to glasses because of the occupancy of the Nd3+ in NaYF4 nanocrystlline phase. The experimental lifetime value of 4F3/2 also enhanced from 124 to 187 µs from G-Nd2 glass to GC-Nd2 glass ceramic and decreased with increasing Nd3+ concentration.