Abstract
In this work we investigate the effect of replacing Na2O by TiO2 on the
structural and spectroscopic characteristics of the Nd2O3-doped
60B(2)O(3)-(20-x)Na2O-10PbO-10Al(2)O(3):xTiO(2):yNd(2)O(3) borate glass
matrix. Measurements of X-ray patterns, glass temperatures (Tg),
vibrational (Raman and infrared (IR)) and optical (absorption and
emission) spectra were carried out. The trend of Tg, the Judd-Ofelt
parameters and Nephelauxetic ratio as the TiO2 and Nd2O3 concentration
increases was interpreted quantitatively and qualitatively in terms of
the network bonds and coordination numbers. Measurements of Tg across
the Nd-doped glass series for different levels of Ti suggests changes in
the rigidity of the matrix due to change of coordination of boron oxide
resulting from the BO4-BO3 back conversion effect. The changes observed
in the Raman and IR spectra are related to the BO3 -> BO4 conversion
effect. The variation of the Judd-Ofelt parameters Omega((2)) and
Omega((6)) indicates that the average rare earth-ligand radius decreases
establishing an electronic density distribution when Nd3+ concentration
increases. This effect is interpreted in terms of Judd-Ofelt parameters
and by the bonding parameter b(1/2) due to Nephelauxetic effect. (C)
2013 Elsevier B.V. All rights reserved.
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