Luminescence of Sr₃Y(BO₃)₃ Activated with Tb³⁺ and Gd³⁺

STACK family borates are promising compounds for optical applications. Synthesis and luminescence of Sr₃Y(BO₃)₃ borate belonging to the STACK family is described. Trivalent activators Tb³⁺ and Gd³⁺ occupy yttrium sites. Owing to fixed, well-separated positions (Y–Y distance 7.396 Å), a large concentration of Gd³⁺, as much as 50% relative to Y, could be accommodated without causing concentration quenching. In the case of Gd³⁺, both excitation and emission lines arise in f–f transitions. Photoluminescence emission is obtained in UV regions. In the case of Tb³⁺, concentration quenching was observed above 2%. Prominent excitation of Tb³⁺ is in the form of a band arising in the f–d-type transition, while emission comes from f–f transitions. Emission lifetimes are of the order of milliseconds, typically forbidden f–f transitions.