FTIR spectroscopy to investigate the role of fluorine on the optical properties of pure and rare earth-doped sol–gel silica

• Published in: Journal of non-crystalline solids Vol. 353; no. 5; pp. 564 - 567
• Main Authors: Baraldi, A., Buffagni, E., Capelletti, R., Mazzera, M., Brovelli, S., Chiodini, N., Lauria, A., Moretti, F., Paleari, A., Vedda, A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2007; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Disordered solids; Exact sciences and technology; FTIR measurements; Glasses; Infrared and raman spectra and scattering; Infrared properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical spectroscopy; Physics; Rare-earths in glasses; Silica; Sol–gels (xerogels); Structure of solids and liquids; crystallography; 78.30.Ly; Sol–gels (xerogels); Optical spectroscopy; FTIR measurements; 63.20.Pw; Rare-earths in glasses; 78.30.−j; Infrared properties; Silica; 78.30.-j; Doping; Glass; Glass structure; Crystal field; Infrared spectra; Precursor; Optical properties; Ordering; Cerium additions; Fourier transform spectra; Sol-gel process; Erbium additions; Sol-gels (xerogels)
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2006.10.024

FTIR spectroscopy is applied to monitor the effects caused by fluorinated precursors (1–10
mol%) in the sol–gel synthesis of silica glasses, either pure or doped with Ce and Er. In pure samples the Si–OH level is heavily reduced to ∼3
×
10
−3
mol%. In doped samples the effect is more limited. The presence of residual fluorine, proved by the Si–F vibrational absorption at ∼950
cm
−1, causes deep changes in the rare-earth (RE) crystal field spectra, which are characterized by narrow absorption lines. The lines broaden if the temperature is increased from 9 to 300
K. The result is discussed in terms either of local ordering around the rare earth ion or by its partial decoupling from the disordered host matrix, due to the creation of network terminating sites.