Design, synthesis and characterization of a novel bluish-green long-lasting phosphorescence phosphor...

Through drawing upon a solid-state reaction, a newly proposed long-lasting phosphor BaLu₂Si₃O₁₀:Eu²⁺, Nd³⁺ is presented and prepared in this work. The thermoluminescence properties of the phosphor are substantially extended, and the long-lasting phosphorescence behavior is markedly intensified by virtue of the consolidation of Nd³⁺ ions which serve as trap centers. In line with density functional theory calculations, the conduction band is mostly composed of Lu 5d states while the Ba 5d states only have a tiny contribution. We analyzed the relationship between the phosphor's electronic structure and its optical properties. The photoluminescence emission spectrum shows a blue emitting band with a wide asymmetric property and an extremum of 426 nm, arising from the 5d-4f transitions of the Eu²⁺ ions which occupy the Ba and Lu sites. It is asserted that the long-lasting phosphorescence of the Eu²⁺ ions which take up both Ba and Lu sites stems from the special form of conduction band and the occupying environment of the emission center. Yet, they have different contributions and induce an interesting phenomenon in which the blue emitting phosphor shows a bluish-green phosphorescence. The long-lasting phosphorescence can last in excess of 6 h at the recognized intensity level (0.32 mcd m^-2) after excitation for 10 min. This work provides a new way of thinking for the development of multicolored LLP materials. This work analyzes and sheds light on the specific courses and provides a likely mechanism for the process.