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Evidences of Rare-Earth Nanophases Embedded in Silica Using Vibrational Spectroscopy

2010; Institute of Electrical and Electronics Engineers; Volume: 57; Issue: 3 Linguagem: Inglês

10.1109/tns.2010.2044420

1558-1578

A. Vedda, N. Chiodini, Mauro Fasoli, A. Lauria, Federico Moretti, Daniela Di Martino, A. Baraldi, E. Buffagni, R. Capelletti, Margherita Mazzera, P. Boháček, E. Mihóková,

Material Dynamics and Properties

Transmission electron microscopy, Raman scattering, Fourier transform infrared spectroscopy, and radio-luminescence are employed to investigate rare-earth (RE) incorporation and aggregate formation in silica glasses prepared by the Sol-Gel method and doped with Ce $^{3+}$ , or Tb $^{3+}$ , Gd $^{3+}$ , Yb $^{3+}$ with concentrations up to several mol%. The results demonstrate that rare-earth aggregates with a mean diameter extending up to several tens of nanometers occur, further increasing their size after post-densification high temperature treatments. Rare-earth segregation causes a reduction of the OH content of glasses. Nanoclusters are amorphous, possibly close to a (RE) $_{2}$ SiO $_{5}$ stoichiometry. Room temperature radio-luminescence measurements reveal that the emission spectra are dominated by RE $^{3+}$ emissions and no bands due to silica matrix defects are detected.