Polarized Raman analyzes of (RE3+) doped fluorotellurite glass and ceramics

Abstract

Several trivalent Rare Earths ions (RE3+) doped glasses and a ceramic with the following stoichiometry 85TeO2-10PbF2-2.5AlF3-2.5REF3 (TPA); RE3+ = (Nd3+, Gd3+ and Yb3+) were studied by polarized Raman Spectroscopy and vibrational analysis. The motivation of this investigation was the understanding of the structural characteristics of the TPA glasses and ceramics. The analysis was done by a detailed band fitting study, the results of which show the combined existence of TeO4 trigonal bipyramid, TeO3+1 and TeO3 trigonal pyramid groups. Furthermore, all the bands associated with the Te–O–Te vibration mode and heavy metal fluorides such as PbF2, AlF3 and REF3 have been assigned and identified with a comparison to previous results in the literature. Finally, a discussion about the Boson Band behavior and corresponding analysis was conducted. Possible origins of the Boson Band are a combination of interaction between light, optical phonons, the tunnelling modes, and the relaxation states. It has been found that non-bridging anion atoms and disordered structures influence Boson bands below 100 cm−1. The thermal treatment for the ceramic process decreased the intensity of Boson bands, likely caused by the destruction of non-bridging anion atoms and their’ inhomogeneous cohesion.