Tuning photoluminescence in layered Pr doped Bi₄Ti₃O₁₂ nanosheets via molten salt process

Novel single-phased and emission-tunable layered Bi₄Ti₃O₁₂:Pr³⁺ nanosheets have been successfully synthesized via molten salt method. The as-prepared samples were characterized by X-ray diffraction and scanning electron microscopy to investigate their crystalline phases and morphologies. Furthermore, we explored the photoluminescence properties of the Bi₄Ti₃O₁₂:Pr³⁺ phosphors, while the cross-relaxation processes between ¹D₂, ³P₀ emitting states and the Pr³⁺–Ti⁴⁺ intervalence charge transfer state, color tuning and thermally stability were discussed in detail. Besides, the emission hue of Bi₄Ti₃O₁₂:Pr³⁺ could be adjusted from white-light (0.3059, 0.2731) to yellow (0.5167, 0.4792) by tuning the excitation wavelength, in which the ratio of ³P₀→³H₄ and ¹D₂→³H₄ was changed. In addition, the increases in temperatures led to the cooperative effects of thermal-quenching behavior and the cross-relaxation processes, thus resulting in the significant decrease of ³P₀→³H₄ emission in comparison to the ¹D₂→³H₄ emission. The results suggested that the Bi₄Ti₃O₁₂:Pr³⁺ is an effective color-tuning phosphor.