In this study, 30 at% Er:RETaO4 (RE = Sc, Y, Gd, Lu) polycrystalline powders were synthesized by the solid-state method. Their structures were determined by the Retvield refinement to X-ray powder diffraction. The optical spectra of the trivalent erbium ions in monoclinic RETaO4 (RE = Sc, Y, Gd, Lu) polycrystalline powders was investigated by absorption and emission measurements at room temperature. Under the excitation of 970 nm laser, the green photoluminescence of 2H11/2, 4S3/2→4I15/2 were observed. The 1 μm and 1.5 μm infrared emissions were also surveyed. The
fluorescence decays of Er3+ from the multiplets 4S3/2 and 4I13/2 were studied at room temperature. It is found that the decay curves from the multiplet 4S3/2 exhibit a non-exponential behavior, which may be due to cross-relaxation processes. At the same time, we investigated that the 2.8μ (due to the transition 4I11/2→4I13/2)
luminescence spectra excited by 808 nm laser.