Compositional dependence of local vibration around rare earth ions in glass-ceramics

Abstract

Compositional dependence of local vibration around in glass-ceramics is investigated by analysing the phonon sideband associated with the transition. Two kinds of sideband peak are observed in a high-energy region of the transition. Phonon energies of these sideband peaks are about and . Intensities of the sidebands are greatly dependent on the composition; the phonon sideband at increases and that at decreases with increasing content. The calculated multiphonon relaxation rate depends only on the intensity of the sideband at . This indicates that multiphonon relaxation of the excited rare earth ion is reduced in lower--content regions. Infrared-to-visible upconversion luminescence of is also measured for glass-ceramics doped with substituted for . Efficient upconversion luminescence is observed at 550 nm under 800 nm excitation. The intensity of the upconversion luminescence becomes remarkably higher in lower--content regions.