Rare earth fluorescence in NASICON type phosphate glass, Na3TiZnP3O12

The emission spectra of Pr3+, Eu3+ and Dy3+ doped in NASICON type phosphate glass, Na3TiZnP3O12 (NTZP) are studied. The dopant rare earth ions occupy sites with 8-9 coordination in a highly covalent environment. For Pr3+ ion, calculated and observed branching ratios for lasing transitions P-3(0) --> H-3(4.6) agree well and found to be 0.64 and 0.24, respectively. The emiss ions of Pr3+ show strong temperature dependence on account of Boltzmann pop ulation of the higher excited states at room temperature. The excitation sp ectrum of Eu3+ gives rise to phonon assisted side band for D-5(2) <-- F-7(0 ) transition at higher energy side with a phonon energy maximum of 1022 cm( -1) and an electron phonon coupling strength (g) of 0.018. The value of pho non energy maximum agrees with infrared spectral data. The results show tha t observation of high energy emissions In phosphate glasses require much hi gher g values. The red/orange and yellow/blue transitions of Eu3+ and Dy3+, respectively show that the Eu3+ occupy more distorted site than Dy3+.