Structure and spectroscopy of rare earth - Doped lead phosphate glasses

Lead-gallium phosphate glasses doped with rare the earth ions (Eu3+, Dy3+, Tb3+, Er3+) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance (207Pb and 31P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO4 crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV-VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu3+ the electron-phonon coupling strength and phonon energy of the glass host were determined. Due to 4f6-4f6 (Eu3+), 4f8-4f8 (Tb3+), 4f9-4f9 (Dy3+) and 4f11-4f11 (Er3+) electronic transitions of trivalent rare earth ions several luminescence bands were stated.