FTIR analysis
FTIR spectrum of un-doped, Nd3+ and Pr3+ doped ZANP glass matrices are recorded and yield similar spectral profiles. Fig. 2 shows FTIR spectral studies of un-doped and 1.0 mol% of rare earth (Nd3+ and Pr3+) doped ZANP glass matrices. It is known that the network of phosphate glasses constituted from cross linking PO4 tetrahedra with three bridging and one terminal double bonded oxygen atoms. In the present FTIR spectrum, the absorption band at 739 cm−1 can be assigned to symmetric stretching vibrations of Psingle bondOsingle bondP bonds [27]. The band at 895 cm−1 can be assigned to asymmetric stretching vibration of Psingle bondOsingle bondP bonds [28], [29] and [30]. The band at 989 cm−1 is attributed to symmetric stretching vibrations of Psingle bondOsingle bondP bonds. The band at 1094 cm−1 is assigned to asymmetric stretching vibrations of chain terminating Q1 group [νas(PO3)2−] [31]. The band at 1268 cm−1 is assigned to asymmetric stretching vibrations of PO2− and Pdouble bond; length as m-dashO bonds [32]. The band around 1680 cm−1 is due to the stretching and bending vibrations of OH groups (Psingle bondOsingle bondH bridges) and molecular water due to absorption of moisture during KBr pellet preparation [33]. The absorption band around 3398 cm−1 is due to presence of hydrogen bonding [34] and [35]. The broad band around 3589 cm−1 is assigned to the presence of Osingle bondH stretching vibration.