Origin of D-band emission in a novel Bi3+-doped phosphor La3SnGa5O14:Bi3+

Abstract

The luminescence characteristics of Bi³⁺ ions in solids have been extensively investigated during recent decades; however, the origin of extra spectra signals (referred to as D-bands) of Bi³⁺ in some compounds still remains ambiguous. In this work, a novel Bi³⁺-doped phosphor La₃SnGa₅O₁₄:Bi³⁺ (LSGO:Bi³⁺) was successfully synthesized via the conventional solid-state reaction method. The structural characteristics, luminescence properties and concentration quenching of the LSGO:Bi³⁺ phosphor were investigated systematically and two emission bands centered at 360 and 540 nm were observed, respectively. The narrow band emission centered at 360 nm was attributed to the transition of ³P₁ → ¹S₀ (A-band) of Bi³⁺ while the broadband emission centered at 540 nm was considered as the D-band emission. A combined experimental and theoretical approach was employed in order to confirm the origin of the D-band emission of LSGO:Bi³⁺. Temperature dependent photoluminescence of LSGO:Bi³⁺ and the fluorescence lifetime of two emission centers were studied. Moreover, the energy of metal-to-metal charge-transfer (MMCT) was also calculated. Ultimately, the D-band emission of LSGO:Bi³⁺ was considered to originate from the forbidden ³P₀ → ¹S₀ electronic transition of Bi³⁺. This work will contribute to a better understanding of the luminescence mechanisms of Bi³⁺ doped phosphors and pave the way toward the future development of new effective Bi³⁺ activated luminescent materials.