Luminescence and decay behaviour of Tb3+:ZrF4-BaF2-LaF3-YF3-AlF3-NaF optical glasses

The present investigation aims at elucidating the photoluminescence behaviour of Tb3+ doped 53ZrF(4)-20BaF(2)-2LaF(3)-2YF(3)-3AlF(3)-(20-x)-NaF-xTbF(3) (where x = 0.2,0.4,0.6,0.8,1.0,1.5 and 2.0 mol%) optical glasses. We have measured two prominently intense emission blue group bands (D-5(3)-->F-7(j=6,5,4,3) at 382, 415, 436 and 461 nm) and green group bands (D-5(4)-->F-7(j=6.5,4,3) at 488, 544, 584 and 623 nm) with an excitation at lambda(exc) = 229 nm (4f(8)-->4f(7)5d(1)) from these ZBLYAN glasses. Under a UV source (15W), more prominent and rich green luminescent colour (544nm) has been noticed from these terbium glasses. In particular, glass with low Tb3+ (0.2 mol%) content has displayed the emission transitions of D-5(3)-->F-7(j=6,5,4,3) and at still higher concentrations these emission bands have disappeared completely because of resonant energy transfer phenomenon or cross-relaxation process. The mechanism behind such a process has been explained in terms of an energy level diagram. Among the seven-terbium glasses, one glass with 1.0 mol% of Tb3+ (as the optimum content) has revealed an intense green emission. (C) 2003 Elsevier B.V. All rights reserved.