Thermally Stable and Deep Red Luminescence of Sr1-xBax[Mg2Al2N4]:Eu2+ (x = 0-1) Phosphors for Solid State and Agricultural Lighting Applications

Julius L. Leanõ, Carl Osby M. Mariano, Wen Tse Huang, Sebastian Mahlik, Tadeusz Lesniewski, Marek Grinberg, Hwo Shuenn Sheu, Shu Fen Hu, Ru Shi Liu

Research output: Contribution to journalArticle

Abstract

The systematic substitution of Ba in the Sr site of Sr[Mg2Al2N4]:Eu2+ generates a deep-red-emitting phosphor with enhanced thermal luminescence properties. Gas pressure sintering (GPS) of all-nitride starting materials in Molybdenum (Mo) crucibles yields pure-phase red-orange-colored phosphors. Peaks in the synchrotron X-ray diffraction (SXRD) data show a systematic shift toward smaller angles due to the introduction of the larger Ba cation in the same crystal structure. The photoluminescence property reveals that Ba substitution shifts the original emission wavelength of Sr[Mg2Al2N4]:Eu2+ (625 nm) toward a690 nm for Ba[Mg2Al2N4]:Eu2+. Thermal stability measurement of Sr1-xBax[Mg2Al2N4] indicates a systematic increase in stability from x = 0 to x = 1. X-ray absorption near-edge spectroscopy (XANES) results demonstrate the coexistence of Eu2+ and Eu3+. The red-shift and the enhanced thermal stability reveals that the distance of the emitting 5d level to the conduction band of Ba[Mg2Al2N4]:Eu2+ is large. The ionic size mismatch of Eu occupying a Ba site reduces the symmetry, thereby further splitting the degenerate emitting 5d level and lowering the energy of the emitting center. The development of deep-red phosphors emitting at 670-690 nm (x = 0.8-1.0) offers possible candidates for plant lighting applications.

Original languageEnglish
Pages (from-to)23165-23171
Number of pages7
JournalACS Applied Materials and Interfaces
Volume12
Issue number20
DOIs
Publication statusPublished - 2020 May 20

Keywords

  • deep red
  • nitride phosphor
  • plant lighting
  • solid-state lighting
  • UCrC-type phosphor

ASJC Scopus subject areas

  • Materials Science(all)

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