Effect of Ga3+ content on the luminous properties of Ce3+-doped Lu2YGaxAl5-xO12 phosphor ceramics for potential lighting application

Abstract

Ce³⁺-doped (Lu,Y)₃(Al,Ga)₅O₁₂ (Ce:LuYGAG) garnet ceramics hold promise as potential phosphor ceramics for lighting applications, yet their luminous properties remain unexplored. To address this issue, garnet nanopowders with compositions of Lu₂YGa_xAl_5-xO₁₂ (x = 1.5, 2.0, 2.5, 3.0) doped with 0.2 at.% Ce were synthesized via a co-precipitation method. These nanopowders served as raw materials for fabricating highly dense ceramics through a combined process of pre-sintering in oxygen followed by hot isostatic pressing (HIP). With the increase of Ga content, the Ce³⁺ luminescence from the lowest 5d₁ level was blue shifted from 507 nm to 498 nm, effectively bridging the "cyan light gap" in the emission spectrum. Furthermore, the full width at half maximum (FWHM) of the emission band broadened from 85 nm to 92 nm, pointing towards the possibility of achieving broadband luminescence. The Ce:Lu₂YGa_1.5Al_3.5O₁₂ demonstrated an impressive luminous efficacy up to 196 lm/W under excitation with 0.9 W laser diode (LD). Upon elevating the LD power to 4.3 W, this optimized ceramic achieved a high luminous flux of 758 lm. Overall, this research reports the luminous properties in Ce:Lu₂YGa_xAl_5-xO₁₂ ceramics through designed Ga³⁺ substitution, paving the way for the development of potential phosphors tailored for various illumination needs.