Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis.

Praseodymium doped NaYF4 nanocrystals in oxyfluoride glass-ceramics; morphological and spectroscopic studies.

The synthesis, morphology, optical properties and excited state dynamics of the Pr-doped NaYF4 nanocrystals in glass-ceramics are presented. The crystalline cubic NaYF4:Pr were synthesized by the controlled heat-treatment of multicomponent oxyfluoride glass based on silica and YF3. A series of the two-hour heat treatments at 620-660 degrees C were carried out yielding visually transparent materials. Above 660 degrees C an opaque material was obtained. The crystalline phase was characterized by the X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The effect of ceramming temperature on the NaYF4:Pr cell parameter (a = 5.470 A for NaYF4 and 5.4899 A, 5.4979 A and 5.5378 A in glass-ceramics) and particle average size (15-40 nm) was observed. Optical characteristics of formed glass-ceramics were favorably affected by the Pr3+ ions in well-defined sites of NaYF4; emission intensities increased and luminescence decay curves become single exponential with the longer corresponding lifetimes.