Self‐reduction process and enhanced blue emission in SrAl₂Si₂O₈: Eu, Tb via electron transfer from Tb³⁺ to Eu³⁺

Abstract

Eu, Tb co-doped SrAl 2 Si 2 O 8 luminescent materials were synthesized via a high-temperature solid-state reaction. Excitation spectra of SrAl 2 Si 2 O 8 : Eu 2þ gives two broad excitation bands maximizing at 270 and 330 nm, resulting from splitting Eu 2þ energy levels in octahedral crystal field. Eu single doped SrAl 2 Si 2 O 8 luminescent material exhibits two emission bands at about 406 and 616 nm. Intensity of the blue emission from Eu 2þ is always strong, compared with that of the red emission band of Eu 3þ . Reduction from Eu 3þ to Eu 2þ can be explained with the model of charge compensation. Blue emission in SrAl 2 Si 2 O 8 : xEu was strengthened after incorporation of Tb, which can be explained by electron transfer from Tb 3þ to Eu 3þ Tb 3þ þ Eu 3þ ! Tb 4þ þ Eu 2þ À Á . Under 230 nm excitation, intensity of Tb 3þ emission was nearly unchanged and that of Eu 2þ was increased, obviously due to the delivery of more electrons to Eu 3þ . The strongest emission of Eu 2þ in 0.09Eu/0.06Tb codoped SrAl 2 Si 2 O 8 and excited at 270 and 330 nm was remarkably enhanced by about four times compared to that of 0.15Eu Single doped SrAl 2 Si 2 O 8 . All of the results indicate that SrAl 2 Si 2 O 8 : xEu, yTb are potential blue emitting luminescent materials for UV-LEDs. More importantly, this research may provide a new perspective in designing broad band blue luminescent materials.

Tunable white light and energy transfer of Eu2+‐Tb3+‐Eu3+ tri‐activated glasses synthesized in air

“…44 For example, Tb 3+ (4f 8 ) + Eu 3+ (4f 6 ) → Tb 4+ (4f 7 ) + Eu 2+ (4f 7 ). 44 For example, Tb 3+ (4f 8 ) + Eu 3+ (4f 6 ) → Tb 4+ (4f 7 ) + Eu 2+ (4f 7 ).…”

“…To our knowledge, when different rare earth ions with conjugate electronic configuration are co-doped into one glass, they may achieve a more stable electronic structure whose 4f electron is seven or a multiple of seven spontaneously. 44 For example, Tb 3+ (4f 8 ) + Eu 3+ (4f 6 ) → Tb 4+ (4f 7 ) + Eu 2+ (4f 7 ). A part of the Tb 3+ ions was oxidized and a part of the Eu 3+ ions was reduced.…”