Effect of Tb3+ concentration and co-doping with Ce3+ ions on luminescence characteristics of terbium-doped (Lu0.25Gd0.75)2SiO5 single crystals

Abstract Solid-solution crystals Lu2SiO5 - Gd2SiO5 (LGSO) single doped with Tb3+ with concentrations 0.8, 1.5 and 4.0 at% and co-doped with 4.0 at% Tb3+ + 0.6 at% Ce3+ were fabricated by the Czochralski technique. Optical absorption spectra were recorded with polarized light. Luminescence and excitation spectra for Tb3+ and Ce3+ were recorded upon CW excitation. Time resolved spectra of Tb3+ and Ce3+luminescence excited by femtosecond light pulses were recorded with a streak camera. It was observed that in Tb3+-doped samples the 5D4 luminescence excited into f-d bands in UV shows an initial rising stage whose dynamics is governed by the decay time of the higher energy 5D3 level. In the LGSO:Tb, Ce phosphor the highest luminescence intensity occurs for excitation wavelengths between 320 nm and 370 nm providing a broad –band emission consisting of vibronic transitions of Ce3+ ions and of 5D4 emission of Tb3+ that is fed from excited Ce3+ ions. It was concluded that LGSO:Tb, Ce is a promising visible phosphor for application purposes.