Thermal and Structural Characterization of Transparent Rare-Earth Doped Lead Fluoride Glass-Ceramics

Abstract

The devitrification of glasses with composition 50GeO 2 -40PbO-10PbF 2 -xREF 3 , RE = Gd, Eu, 0 < x ≤ 2, leads to glass ceramics made of RE 3+ : β-PbF 2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE 3+ : β-PbF 2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE 3+ +: β-PbF 2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF 2 solid solution results from a combined effect of Pb 2+ -RE 3+ substitution and interstitial F– introduction. In the glass ceramics, RE 3+ : β-PbF 2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.