Spectroscopic studies of rare earth ions in MgSiO3 gel-derived crystals

The spectroscopic properties of Eu3+, Tb3+, Sm3+, Dy3+ and Er3+ ions in MgSiO3 gel and the MgSiO3 gel-derived crystals have been investigated. The main excitation band of Eu3+ ions and Tb3+ ions in the gel-derived crystal is attributed to a charge transfer transition and 4f–5d transition, respectively. The emission bands of Tb3+ ions in the gel appear at the same positions as in the gel-derived crystal and the relative intensities of the groups of bands are approximately the same. Similar to Eu3+ ions, however, the intensities of emission bands of Tb3+ ions in the gel-derived crystal are orders of magnitude greater than that in the gel since multiphonon relaxation effectively competes with radiative transitions due to the higher phonon energy in the gel. The energy level split caused by crystal field is observed clearly in the emission spectra of Eu3+ and Sm3+ ion activated gel-derived crystals. The excitation and emission spectra of Sm3+ and Dy3+ ions in the gel-derived crystal are predominantly different from that in the gel. In contrast, 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 bands.