Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Tokyo 171-8588, Japan.
Inorg Chem. 2011 Jun 20;50(12):5389-95. doi: 10.1021/ic101955v. Epub 2011 May 23.
We synthesized polycrystalline pristine and Pr(3+)-doped perovskites La(1/3)MO(3) (M = Nb, Ta):Pr(3+) and investigated their crystal structure, optical absorption, and luminescence properties. The optical band gap of La(1/3)NbO(3) (3.2 eV) is smaller than that of La(1/3)TaO(3) (3.9 eV), which is primarily due to the difference in electronegativity between Nb and Ta. In La(1/3)NbO(3):Pr(3+), the red emission assigned to the f-f transition of Pr(3+) from the excited (1)D(2) level to the ground (3)H(4) state upon band gap photoexcitation (near-UV) was observed, whereas the f-f transition of Pr(3+) with blue-green emission from the excited (3)P(0) level to the ground (3)H(4) state was quenched. On the other hand, in La(1/3)TaO(3):Pr(3+), the blue-green emission upon band gap photoexcitation was observed. Their differences in emission behavior are attributed to the energy level of the ground and excited states of 4f(2) for Pr(3+), relative to the energy levels of the conduction and valence bands, and the trapped electron state, which mediates the relaxation of electron from the conduction band to the excited state of Pr(3+). La(1/3)NbO(3):Pr(3+) is a candidate red phosphor utilizing near-UV LED chips (e.g., λ = 375 nm) as an excitation source.
我们合成了多晶的纯净和 Pr(3+)掺杂的钙钛矿 La(1/3)MO(3)（M = Nb，Ta）：Pr(3+)，并研究了它们的晶体结构、光学吸收和发光性能。La(1/3)NbO(3)（3.2 eV）的光学带隙小于 La(1/3)TaO(3)（3.9 eV），这主要是由于 Nb 和 Ta 之间的电负性差异。在 La(1/3)NbO(3):Pr(3+)中，观察到了归因于 Pr(3+)从激发态（1）D(2)能级到基态（3）H(4)态的 f-f 跃迁的红色发射，当带隙光激发（近紫外）时，而来自激发态（3）P(0)能级到基态（3）H(4)态的带隙光激发的 f-f 跃迁的 Pr(3+)的蓝绿色发射被猝灭。另一方面，在 La(1/3)TaO(3):Pr(3+)中，观察到了带隙光激发的蓝绿色发射。它们的发射行为的差异归因于 4f(2)的基态和激发态的能级相对于导带和价带的能级以及俘获电子态，后者介导电子从导带向 Pr(3+)的激发态的弛豫。La(1/3)NbO(3):Pr(3+)是一种候选的红色磷光体，利用近紫外 LED 芯片（例如，λ = 375 nm）作为激发源。
