基于第一性原理计算的Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)长余辉材料持续发光机理

Persistent Luminescence Mechanism of Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)Long Afterglow Material Based on First-Principles Calculations

长余辉材料应用广泛,但种类繁多、发光机理难以被普遍阐释。针对发光–余辉性能好的Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)硅酸盐长余辉材料,构建Sr_(2)MgSi_(2)O_(7)基质、Eu掺杂及(Eu,Dy)共掺杂Sr_(2)MgSi_(2)O_(7)的分子模型,进行第一性原理计算。从电子结构角度解译电子跃迁俘获路径,并阐释Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)的持续发光机理。结果表明:Eu、Dy离子的掺入使Sr_(2)MgSi_(2)O_(7)由间接带隙半导体转变为直接带隙半导体;Dy 5d态主要位于Fermi能级与Eu 5d态之间,并与Eu 5d态存在能量重叠,这证实了Dy3+作为电子陷阱的合理性。Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)发光过程的揭示有助于后续光学性能的调控与提升。

Long afterglow materials are widely used,but their luminescence mechanism is difficult to be universally explained.For Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)silicate long afterglow material with good luminescence–afterglow properties,the molecular models of Sr_(2)MgSi_(2)O_(7)substrate,Eu doped and(Eu,Dy)co-doped Sr_(2)MgSi_(2)O_(7)were constructed,and the first-principles calculations were carried out.From the perspective of electronic structure,the electron transition trapping path is revealed to explain the persistent luminescence mechanism of Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+).The results showed that the doping of Eu and Dy ions changed Sr_(2)MgSi_(2)O_(7)from an indirect band gap semiconductor to a direct band gap semiconductor.The Dy 5d state was mainly located between the Fermi level and the Eu 5d state,and it had energy overlap with the Eu 5d state,which confirmed the rationality of Dy3+as an electron trap.The luminescence process of Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)was revealed,which is helpful for the subsequent regulation and improvement of optical properties.