Effect of post-heat-treatment on the structural, spectroscopic and dissolution properties of a highly stable Er³⁺-doped multi-component phosphate glass

Abstract

<p>In this paper, the impact of the post-heat-treatment on the structural and spectroscopic properties as well as on the chemical durability of a thermally stable Er<sup>3+</sup>-doped phosphate glass in the system P<sub>2</sub>O<sub>5</sub> - K<sub>2</sub>O - Al<sub>2</sub>O<sub>3</sub> - B<sub>2</sub>O<sub>3</sub> - BaO - PbO - La<sub>2</sub>O<sub>3</sub> - Gd<sub>2</sub>O<sub>3</sub> is reported. Two crystalline phases, namely La, Gd-monazite and AlKP<sub>2</sub>O<sub>7</sub>, were found to precipitate from the surface of the glass after heat-treatment, as confirmed by both X-ray Diffraction (XRD) and Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX) analyses. Moreover, the heat-treatment was responsible for the formation of a more polymerized glass network close to the surface crystalline layer as evidenced using micro-Raman spectroscopy. From the changes in the Er<sup>3+</sup> optical properties, some of the Er<sup>3+</sup> ions are suspected to enter in the crystals. Both the as-prepared and heat-treated glasses were subjected to a degradation test in hydrochloric acid (HCl) and showed a congruent and incongruent dissolution behavior, respectively.</p>