New localized/delocalized emitting state of Eu2+ in orange-emitting hexagonal EuAl2O4

Liu, Feng; Meltzer, Richard S.; Li, Xufan; Budai, John D.; Chen, Yu -Sheng; Pan, Zhengwei

doi:10.1038/srep07101

New localized/delocalized emitting state of Eu²⁺ in orange-emitting hexagonal EuAl₂O₄

Journal Article · Tue Nov 18 00:00:00 EST 2014 · Scientific Reports

DOI:https://doi.org/10.1038/srep07101· OSTI ID:1185339

Liu, Feng ^[1]; Meltzer, Richard S. ^[1]; Li, Xufan ^[1]; Budai, John D. ^[2]; Chen, Yu -Sheng ^[3]; Pan, Zhengwei ^[1]

Univ. of Georgia, Athens, GA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of Chicago, Argonne, IL (United States)

Eu²⁺-activated phosphors are being widely used in illuminations and displays. Some of these phosphors feature an extremely broad and red-shifted Eu²⁺ emission band; however, convincing explanation of this phenomenon is lacking. Here we report a new localized/delocalized emitting state of Eu²⁺ ions in a new hexagonal EuAl₂O₄ phosphor whose Eu²⁺ luminescence exhibits a very large bandwidth and an extremely large Stokes shift. At 77 K, two luminescent sites responsible for 550 nm and 645 nm broadband emissions are recognized, while at room temperature only the 645 nm emission band emits. The 645 nm emission exhibits a typical radiative lifetime of 1.27 μs and an unusually large Stokes shift of 0.92 eV. We identify the 645 nm emission as originating from a new type of emitting state whose composition is predominantly that of localized 4f⁶5d character but which also contains a complementary component with delocalized conduction-band-like character. This investigation gives new insights into a unique type of Eu²⁺ luminescence in solids whose emission exhibits both a very large bandwidth and an extremely large Stokes shift.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Science (SC)

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1185339

Alternate ID(s):: OSTI ID: 1171254

Journal Information:: Scientific Reports, Journal Name: Scientific Reports Vol. 4; ISSN 2045-2322

Publisher:: Nature Publishing GroupCopyright Statement

Country of Publication:: United States

Language:: English

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Cited By (1)

The self-reduction synthesis and luminescent properties of Eu ²⁺ /Eu ³⁺ activated BaZr _x Si ₃ O _{7+2 x} phosphors with white light emission for white light-emitting diodes Zhong, Jianlin; Yu, Lixin; Man, Xiaoqin Luminescence, Vol. 33, Issue 8 https://doi.org/10.1002/bio.3559	journal	October 2018

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