Abstract
Er3+-doped tellurite glasses with molar compositions of 75TeO2–20ZnO–(5 − x) Na2O–xEr2O3 (x = 0, 0.5, 1, 2, 3, and 4 mol%) have been elaborated from the melt-quenching method. The effects of Er2O3 concentration on the thermal stability and optical properties of tellurite glasses have been discussed. From the differential
scanning calorimetry (DSC) profile, the glass transition temperature T
g, and crystallization onset temperature T
x are estimated. The thermal stability factor, defined as ∆T = T
x − T
g, was higher than 100 °C. It suggests that tellurite glass exhibits a good thermal stability and consequently is suitable
to be a potential candidate for fiber drawing. Furthermore, the stability factor increases with Er2O3 concentration up to 2 mol% then presents a continue decrease suggesting of beginning of crystallization of highly doped tellurite
glasses. The refractive index and extinction coefficient data were obtained by analyzing the experimental spectra of tanΨ
and cos∆ measured by spectroscopic ellipsometry (SE). The complex dielectric functions (ε = ε1 + iε2) of the samples were estimated from regression analysis. The fundamental absorption edge has been identified from the optical
absorption spectra and was analyzed in terms of the theory proposed by Davis and Mott. The values of optical band gap for
direct and indirect allowed transitions have been determined. An important decrease of the optical band gap was found after
Er doping. It was assigned to structural changes induced from the formation of non-bridging oxygen. The absorption coefficient
just below the absorption edge varies exponentially with photon energy indicating the presence of Urbach’s tail. The origin
of the Urbach energy is associated with the phonon-assisted indirect transitions.
scanning calorimetry (DSC) profile, the glass transition temperature T
g, and crystallization onset temperature T
x are estimated. The thermal stability factor, defined as ∆T = T
x − T
g, was higher than 100 °C. It suggests that tellurite glass exhibits a good thermal stability and consequently is suitable
to be a potential candidate for fiber drawing. Furthermore, the stability factor increases with Er2O3 concentration up to 2 mol% then presents a continue decrease suggesting of beginning of crystallization of highly doped tellurite
glasses. The refractive index and extinction coefficient data were obtained by analyzing the experimental spectra of tanΨ
and cos∆ measured by spectroscopic ellipsometry (SE). The complex dielectric functions (ε = ε1 + iε2) of the samples were estimated from regression analysis. The fundamental absorption edge has been identified from the optical
absorption spectra and was analyzed in terms of the theory proposed by Davis and Mott. The values of optical band gap for
direct and indirect allowed transitions have been determined. An important decrease of the optical band gap was found after
Er doping. It was assigned to structural changes induced from the formation of non-bridging oxygen. The absorption coefficient
just below the absorption edge varies exponentially with photon energy indicating the presence of Urbach’s tail. The origin
of the Urbach energy is associated with the phonon-assisted indirect transitions.
- Content Type Journal Article
- DOI 10.1007/s10853-010-4820-x
- Authors
- I. Jlassi, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
- H. Elhouichet, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
- M. Ferid, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
- Journal Journal of Materials Science
- Online ISSN 1573-4803
- Print ISSN 0022-2461
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