Synthesis and photoluminescence properties of (Y,Gd)Al3(BO3)4:Tb3+ under VUV excitation

Single phase of Y x Gd 0.5− x Tb 0.5 Al 3 (BO 3 ) 4 (0 ≤ x ≤ 0.5) was prepared by the thermal decomposition of the corresponding nitrates. The main broad band in 120–178 nm and some other bands in 178–288 nm were observed in the excitation spectrum of Gd 0.5 Tb 0.5 Al 3 (BO 3 ) 4 monitored at 541 nm. The former could be assigned to overlapped absorptions among the f → d transition of Gd 3+ , charge transfer bands of O 2− → Ln 3+ (Ln = Tb, Gd) and BO 3 groups. The latter was ascribed to 4f 8 → 4f 7 5d transitions of Tb 3+ . Under 147 nm excitation the maximum emission peak was observed at about 541 nm in the emission spectrum of Gd 0.5 Tb 0.5 Al 3 (BO 3 ) 4 , which was due to the 5 D 4 → 7 F 5 transition of Tb 3+ ; when substituting Gd 3+ with appropriate Y 3+ , the emission intensity of the 5 D 4 → 7 F 5 transition of Tb 3+ increased, and the optimum emission was obtained at x = 0.1 in Y x Gd 0.5− x Tb 0.5 Al 3 (BO 3 ) 4 . This could be due to that electronic transitions occurred from O 2− : 2 p 6 to Y 3+ : 4 p 6 (4d + 5s) and the absorbed energy transferred to Tb 3+ finally, as observed in the excitation spectrum of Y 0.1 Gd 0.4 Tb 0.5 Al 3 (BO 3 ) 4 . The decay time of the 5 D 4 → 7 F 5 transition of Tb 3+ decreased after Y 3+ replacing Gd 3+ , which could be attributed to increasing defect impurities in Y 0.1 Gd 0.4 Tb 0.5 Al 3 (BO 3 ) 4 under 147 nm excitation.