Tellurite glasses have garnered considerable interest
as optical
host materials due to their advantageous properties, including low
processing temperature, high resistance to corrosion and crystallization,
and excellent solubility for rare earth ions. However, their applicability
in the infrared (IR) region is limited by the absorption of species
with distinct vibrations. The incorporation of fluorides has emerged
as a promising approach to reduce hydroxyl (OH) absorption during
the precursor melting process. In this study, we investigated the
influence of ZnF2 on a glass matrix composed of TeO2-ZnO-Na2O, resulting in notable changes in the
glass structure and optical properties, with Eu3+ serving
as an environmental optical probe. The samples underwent comprehensive
structural, thermal, and optical characterization. Structural analyses
encompassed 19F and 125Te nuclear magnetic resonance
(NMR), with the latter being complemented by mathematical simulations,
and these findings were consistent with observations from Raman scattering.
The main findings indicate an enhancement in thermal stability, modifications
in the Te–O connectivity, and a reduction in emission intensity
attributed to the effects of ligand polarizability and symmetry changes
around Eu3+. Additionally, the fluorotellurite matrices
exhibited a shift in the absorption edge toward higher energies, accompanied
by a decrease in mid-IR absorptions, thereby expanding the transparency
window. As a result, these glass matrices hold substantial potential
for applications across various regions of the electromagnetic spectrum,
including optical fiber drawing and the development of solid-state
emitting materials.