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

Julius L Leaño Jr; Carl Osby M Mariano; Wen-Tse Huang; Sebastian Mahlik; Tadeusz Lesniewski; Marek Grinberg; Hwo-Shuenn Sheu; Shu-Fen Hu; Ru-Shi Liu

doi:10.1021/acsami.0c07345

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

ACS Appl Mater Interfaces. 2020 May 20;12(20):23165-23171. doi: 10.1021/acsami.0c07345. Epub 2020 May 8.

Authors

Julius L Leaño Jr^{1

2

3}, Carl Osby M Mariano⁴, Wen-Tse Huang¹, Sebastian Mahlik⁵, Tadeusz Lesniewski⁵, Marek Grinberg⁵, Hwo-Shuenn Sheu⁶, Shu-Fen Hu⁴, Ru-Shi Liu^{1

7}

Affiliations

¹ Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
² Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei 10617, Taiwan.
³ Philippine Textile Research Institute, Department of Science and Technology, Taguig City 1631, Philippines.
⁴ Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan.
⁵ Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Gdańsk University, Wita Stwosza 57, 80-308 Gdańsk, Poland.
⁶ National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan.
⁷ Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 10608, Taiwan.

PMID: 32338495
DOI: 10.1021/acsami.0c07345

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 ∼690 nm for Ba[Mg₂Al₂N₄]:Eu²⁺. Thermal stability measurement of Sr_1-xBa_x[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.

Keywords: UCr4C4-type phosphor; deep red; nitride phosphor; plant lighting; solid-state lighting.