Characterization of lithium-magnesium-tellurite doped with erbium and neodymium glass

Tellurite glass based on (78-x)TeO2-10Li2O-10MgO-2Nd2O3-xEr2O3, (where x = 0.4 to 2.0 mol %) has successfully been prepared by melt-quenching technique. The colour of glass is found to vary from light violet to dark violet as the Er2O3 content is increased. No definite peaks are found from the X-ray diffraction pattern, which shows that the glass is amorphous in nature. It also found that the densities and the molar volume of the glass increase as the Er2O3 content is increased. The glass transition temperature (Tg), crystallization temperature (Tc), melting temperature (Tm) and the temperature difference (Tc-Tg) are determined by means of Differential Thermal Analysis (DTA). It is found that the Tc, Tg and Tm are in the range of (419-430) oC, (300-345) oC and (885-890) oC respectively. Meanwhile, the vibrational study is conducted using the Infrared spectroscopy in the range of (4000-400) cm–1. Two major absorption peaks are observed around (1600-3600) cm–1, and (900-1200) cm–1 which are due to the stretching mode vibration of OH peak and Te-OH peak respectively. The optical absorption edge is studied using UV-Vis spectroscopy. The result shows that the optical band gap (Eopt) and Urbach Energy (?E) are in the range of (3.038-3.130) eV and (0.334-0.321) eV respectively, depending on the Er2O3 concentration. The refractive index is evaluated using the Sellmeier’s equation and it is found that the value in the visible region is in the range of 1.724-1.781 depending on the Er2O3 content. The emission spectrum is recorded using the photoluminescence spectrometer excited at 582 nm at room temperature. The result shows that the emission spectrum of Er3+ and Nd3+ consist of five emission bands at ~457 nm, ~495 nm, ~556 nm, ~611 nm, and ~ 665 nm which can be assigned as a transition of 4F7/2-4F15/2, 4S3/2-4F15/2, 4G11/2 - 4I9/2, 4G11/2 - 4I15/2 and 4G7/2 - 4I13/2 respectively