Intrinsic luminescence of rare-earth oxyorthosilicates

The spectra and decay kinetics of luminescence and the excitation and reflection spectra of the luminescence of orthosilicates A2SiO5 (A = Y, Lu, Sc, Gd), both nominally pure and doped with cerium, are measured using time-resolved VUV spectroscopy in the ranges of energies ħν = 1.5–16 eV and temperatures T = 8–3000 K. The band structure of the crystals is calculated in the local electron density approximation (LDA). The origin of the intrinsic luminescence in the crystals studied is established, and the assumption regarding the existence of self-trapped excitons and their structure is made.