Influence of rare earth elements (Sc, La, Gd and Lu) on the luminescent properties of green phosphor Y2SiO5:Ce,Tb

Systematic studies on CL and PL for rare earths (Sc3+, La3+, Gd3+ and Lu3+) doped Y2SiO5:Ce,Tb phosphor were performed and the formula (Y0.965−xRxTb0.03Ce0.005)2SiO5 (R = Sc, La, Gd and Lu) was applied to represent the compositions of the samples. Sensitizing influence of Ce3+ on Tb3+ can only be observed with the excitation of cathode rays and 355 nm UV. For the La3+ doped system, the PL intensity increased nearly 30% at x = 0.03; and for the Lu3+ doped system, the intensity increased about 20% at x = 0.20. Whereas doping of the Gd3+ and the Sc3+ reduced the intensity: at x = 0.3, the PL intensity decreased 10% for the Gd3+ doped system and about 25% for Sc3+. CL measurements showed that except the Sc3+, other rare earths doping improved the intensities: the La3+ doping made the intensity enhancement of about 10% at x = 0.03; the Gd3+ 35% at x = 0.1–0.3 and Lu3+ 25% at x = 0.1–0.2. For the Sc3+ doped samples, the CL intensity decreased about 25% at x = 0.2. The energy transfer processes were discussed for the Gd3+ doped samples. Two transfer processes from the Gd3+ to the Tb3+ were proposed: Gd3+ → Tb3+ and Gd3+ → Ce3+ → Tb3+.