SPECTROSCOPIC STUDIES OF RARE-EARTH IONS IN MGSIO3 GEL-DERIVED CRYSTALS

The spectroscopic properties of Eu3+, Tb3+, Sm3+, Dy3+ and Er3+ ions i n MgSiO3 gel and the MgSiO3 gel-derived crystals have been investigate d. The main excitation band of Eu3+ ions and Tb3+ ions in the gel-deri ved crystal is attributed to a charge transfer transition and 4f-5d tr ansition, respectively. The emission bands of Tb3+ ions in the gel app ear at the same positions as in the gel-derived crystal and the relati ve intensities of the groups of bands are approximately the same. Simi lar to Eu3+ ions, however, the intensities of emission bands of Tb3+ i ons in the gel-derived crystal are orders of magnitude greater than th at in the gel since multiphonon relaxation effectively competes with r adiative transitions due to the higher phonon energy in the gel. The e nergy level split caused by crystal field is observed dearly in the em ission spectra of Eu3+ and Sm3+ ion activated gel-derived crystals. Th e excitation and emission spectra of Sm3+ and Dy3+ ions in the gel-der ived crystal are predominantly different from that in the gel. In cont rast, the excitation and emission spectra of Er3+ ions in gel-derived crystal are approximately the same as that in the gel with respect to the positions, numbers and intensities of excitation and emission band s. (C) 1997 Elsevier Science S.A.