structural and optical properties of novel boro tellurite glass-ceramic with composition B2O3TeO2-BaO-Dy2O3

Abstract

Glass-ceramic material was created with varying compositions of (50-x) B2O3-25TeO2-25BaO-xDy2O3, where x ranged from 0 to 1.25 mol%. The initial step involved preparing the glasses before the glass-ceramic formation process commenced. The glasses, which were subjected to a carefully controlled heat treatment. Subsequently, a comprehensive analysis of the glasses was conducted using advanced spectroscopic methods including XRD, FTIR, Raman, UV-Vis, and PL spectroscopies. The analysis conducted using FTIR spectroscopy unveils crucial insights into the composition of the network structure in the studied samples. Specifically, it indicates the presence of TeO3 and TeO4 units of γ-TeO2, as well as TeO4 tetragonal bipyramids featuring bridging oxygen. The presence of [TeO3] in the glass is expected to undergo a transformation into [TeO4] during the heat treatment process. As a result, the projected transformation is expected to lead to a decrease in the number of NBOs that exist within the glass network. By utilizing Raman spectroscopy, it has been determined that crystalline TeO2 displays two distinct polymorphic forms characterized by different planes. Among these forms, the tetragonal α-TeO2, commonly known as paratellurite, and the orthorhombic β-TeO2, referred to as Tellurite, are the prominent ones. The glass-ceramic samples exhibit a shift towards lower wavelengths in their optical absorption cutoff wavelength (λcutoff) as determined by UV-vis measurements conducted in the spectral range of 300-1100 nm. The samples that were prepared underwent analysis to determine various properties including the optical energy gap value through the utilization of Tuac’s plot. Additionally, the refractive index of the system under study were also determined.