Preparation and optical studies of Er-doped Al-Si-Ti oxide glasses using the ErAl3(OPri)12 isolated Er-ion precursor

We have investigated the possibility of avoiding formation of Er-rich oxide clusters in ErAl3O6-TiO2-SiO2 glassy films. Samples containing 0.5, 1 and 3 mol% Er3+ were prepared using a precursor with a single, isolated Er-ion, ErAl3(OPri)(12), in the metal-organic sol-gel route. The thermal decomposition of the gel films to form amorphous oxide films was studied by thermogravimetry, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction and by means of a transmission electron microscope, equipped with an energy dispersive spectrometer. The microscopy studies of the oxide films obtained after 2 h at 900 degrees C showed that they were amorphous and free of Er-rich clusters. The optical and vibrational properties of the glasses were studied using FT-IR, Raman scattering and luminescence spectroscopy. The samples exhibit luminescence both in the visible and IR under excitation of the 514.5 and 488 nm Ar+ laser lines. The emission around 1.5 mu m was maximum for the 1 mol% sample. The results show that the preparation technique can produce samples with an unusually large amount of Er doping, before Er-clustering induced quenching of the luminescence appears. Up-converted emission was also detected around 21 000 and 24 500 cm(-1). (C) 1999 Elsevier Science Ltd. All rights reserved.