| Summary: | Two series of tellurite glasses with molar compositions of (55TeO _2 –2Bi _2 O _3 –(41-x) ZnO–2Na _2 O–xNd _2 O _3 (x = 0.5, 1.0, 1.5, 2.0 and 2.5) and 55TeO _2 –2Bi _2 O _3 –(41-x) ZnO- x Na _2 O-2Nd _2 O _3 (x = 1.0, 2.0, 3.0, 4.0, 5.0) were fabricated using melt quenching technique. Based on the measured densities, refractive indices and absorption spectra, physical and spectroscopic properties of these two-glass series are evaluated and compared. Whereas substitution of ZnO by Nd _2 O _3 causes the values of density and refractive index increase, the substitution of ZnO by Na _2 O has been shown to impact the glass density and refractive index in the opposite manner. Molar volume of both series increases with an increase of either Nd _2 O _3 or Na _2 O concentrations. In this regard, a dynamical model explaining the density and molar volume was proposed. Additionally, Judd-Ofelt theory was applied in order to predict the physical and laser properties of the two glasses series as a function of glass compositions, i.e., Judd-Ofelt parameters Ω _t ( t = 2, 4, 6), branching ratios ( β ), calculated lifetimes ( τ ), the emission to exited state absorption intensity ratio ( A _em / A _ESA ) and spectroscopic quality χ = Ω _4 /Ω _6 . Equations to relate χ with branching ratios for laser transitions ^4 F _3/2 to ^4 I _J’ (with J ′ = 9/2, 11/2, 13/2 and 15/2) were also derived.
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