Structure and Optical Properties of Sodium Aluminium Phosphate Glass Matrix Containing Lanthanide Oxides (Ce, Pr, Nd and Gd).

Lanthanides (Ce, Pr, Nd and Gd) 1, 3, 5 and 10 wt% of each were loaded into a pristine sodium aluminium phosphate glass matrix in order to simulate the immobilization of minor actinides (Am, Np, Cm) produced from spent nuclear fuel reprocessing. The optical parameters pertaining to these glasses were derived from the diffuse reflectance spectra. The systematic dependence of the physical and structural properties of these glasses on the dopants and the concentration of the latter was studied by XRD and Raman spectroscopy. The results on Rare Earth (RE) doped sodium aluminium phosphate are being reported for the first time. The physical parameters such as density, molar volume and oxygen packing density were evaluated. The XRD patterns showed the absence of any crystalline phase in these glasses. The relative % areas of (PO3)−2(Q2) bonds increase, whereas Q0 and Q1 tend to decrease with the addition of lanthanide oxides as compared to the pristine glass. The addition of different lanthanide oxides was found to depolymerize the network by forming more Q2 short chains. The results showed that the band gap energy (Eg) depends strongly on the cation field strength (CFS) of the lanthanides. The band gap energy decreases with an increase in the lanthanide concentration in the glass matrix. Praseodymium-doped glasses showed the highest Eg values (5.28–5.23 eV). The photoluminescence spectra confirm the characteristic excitation and emission peaks for the cations Ce+3, Pr+3 and Gd+3 and their variation with concentration was analysed. [ABSTRACT FROM AUTHOR]