Effects of Tm³⁺ Additions on the Crystallization of LaF₃ Nanocrystals in Oxyfluoride Glasses: Optical Characterization and Up‐Conversion

Abstract

The influence of the addition of 1 mol% Tm2O3 on the nanocrystallization of LaF3 in a glass of composition 55SiO2–20Al2O3–15Na2O–10LaF3 (mol%) has been studied. Tm2O3 affects the phase separation in the glass and delays the onset of crystallization with respect to the undoped glass. Additionally, the maximum LaF3 crystal size is slightly greater than that in the undoped glass–ceramics. The microstructural and compositional changes in the glass matrix have been studied using several techniques, including viscosity, dilatometry, X‐ray and neutron diffraction (XRD, ND), quantitative Rietveld refinement, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and Raman spectroscopy. Photoluminescence measurements indicate that the Tm3+ ions are distributed between the glassy matrix and LaF3 crystals. Eu2O3 has been used as structure probe and part of the Eu3+ ions are reduced to Eu2+ when incorporated in the LaF3 nano‐crystals. Up‐conversion spectra under IR‐excitation show a higher intensity of the blue emission in the Tm‐doped glass–ceramic compared with that in the glass.

Transparent Oxyfluoride Nano-Glass Ceramics Doped with Pr3+ and Pr3+–Yb3+ for NIR Emission

“…2, crystallization activation energies were calculated and their values are (329 ± 16) kJ/mol and (342 ± 18) kJ/mol for 0.1-0.5 Pr-Yb and 0.5-1 Pr-Yb, respectively. These results are similar to those obtained for the un-doped (de Pablos-Martín et al, 2011) and Tm 3+ doped glass (de Pablos-Martín et al, 2013), Avrami n parameter was calculated, using Eq. 1, from the slope of each line; a n mean value was obtained from the slope of the five lines represented in Figures 2A,B for 0.1-0.5 Pr-Yb and 0.5-1 Pr-Yb, respectively.…”

“…This means that the use of Kissinger equation is valid for the calculation of the crystallization activation energy and corresponds to a volumetric crystallization with crystal growth controlled by diffusion (Donald, 2004). The same (n, m) parameters were also obtained for the un-doped glass and for Tm 3+ doped glass (de Pablos- Martín et al, 2013), confirming that dopants do not affect the crystallization mechanism but may affect the crystallization kinetics and influence LaF3 crystals size.…”

“…Samples doped with only Pr 3+ were also prepared for comparison of the optical properties. A more complete description of glass preparation was given in (de Pablos-Martín et al, 2011).…”

“…The properties of the un-doped glass system have been extensively studied elsewhere (Bhattacharyya et al, 2009;Hemono et al, 2009;de Pablos-Martín et al, 2011).…”

Long-lived emission from Eu3+:PbF2 nanocrystals distributed into sol–gel silica glass

“…After heat treatment, local symmetry around the optically active dopant (Eu 3? ions) and participation of ionic bonds increased [20]. The value of R is decreased due to incorporation of RE 3?…”