Luminescent investigations of Li₆Lu(BO₃) ₃:Tb³⁺, Dy³⁺ phosphors

In our novel work we report the luminescence properties of Terbium (Tb ³⁺) and Dysprosium (Dy³⁺) ions in Li₆Lu(BO ₃)₃ (lithium lutetium borate) phosphors with its specific and productive use in various luminescent display systems. We have synthesized Tb³⁺ and Dy³⁺ doped Li₆Lu(BO₃) ₃ phosphors by the solid state reaction method. Concentration based optimization of activators is attained i.e. 2 mol% for Tb³⁺ and 5 mol% for Dy³⁺. XRD (X-ray diffraction) and FE-SEM (Field emission-scanning electron microscopy) were used to analyze the overall morphologies, crystalline structures and the grain sizes of the prepared phosphors. Moreover, the grain size of 20 μm is confirmed via Scherrer's formula. In order to characterize the luminescence properties of the synthesized phosphors, we measured its X-ray induced luminescence, proton induced luminescence and UV induced photoluminescence. Under UV luminescence Dy ³⁺ doped phosphor, it displayed seven obvious peaks corresponding to transitions from ⁶H_15/2 (f⁹) ground state to higher energy state of 4f⁹ whereas, UV-emission spectrum of Li ₆Lu(BO₃)₃:Tb³⁺ phosphor has shown five major transitions with each peak consists of several smaller lines, confirming the complicated transition (⁵D_j → ⁷F_j) behavior of Tb³⁺. The light yield calculated for Li₆Lu(BO₃)₃:Tb³⁺ is 75% that of (Y,Gd)₂O₃:Eu³⁺ phosphor which is a well known commercially available material for PDP (Plasma Display Panel). It is observed that due to the presence of Lutetium, the synthesized phosphor has high effective atomic number (Z_eff = 52) as well as high molecular weight (M.Wt = 393 g/mol) which makes lithium lutetium borate one of the promising candidates for X-ray imaging in medical field. Furthermore, the presence of ⁶Li and ¹⁰B could make Li ₆Lu(BO₃)₃ phosphor as a potential neutron detector.