Single Crystal Growth of the Orthoborate NaBaLu(BO₃)₂ and Optical Investigation of Eu³⁺ and Tb³⁺ Doped NaBaLu(BO₃)₂

Sodium barium lutetium borate NaBaLu(BO3)2 crystals were synthesized using a high-temperature solution method. The crystal structure of this layered orthoborate is described and corresponds to that of an extensive orthoborates family, NaBaR(BO3)2 (R = Sc, Y, Yb, Tb – Lu). NaBaLu(BO3)2 was doped by Eu3+ and Tb3+ to explore its performance as a host material and to investigate the luminescent properties of the Eu3+ and Tb3+ doped materials. The emission spectra of the NaBaLu(BO3)2:Ln (Ln = Eu, Tb) crystals are presented. The most intensive peak of NaBaLu(BO3)2:Eu, located at 592 nm, corresponds to the red emission, while the most intensive peak of NaBaLu(BO3)2:Tb, located at 550 nm, is associated with green emission.