Bluish-White Luminescence in Rare-Earth-Free Vanadate Garnet Phosphors: Structural Characterization of LiCa3MV3O12 (M = Zn and Mg)

Takuya Hasegawa; Yusuke Abe; Atsuya Koizumi; Tadaharu Ueda; Kenji Toda; Mineo Sato

doi:10.1021/acs.inorgchem.7b02820

Bluish-White Luminescence in Rare-Earth-Free Vanadate Garnet Phosphors: Structural Characterization of LiCa₃MV₃O₁₂ (M = Zn and Mg)

Inorg Chem. 2018 Jan 16;57(2):857-866. doi: 10.1021/acs.inorgchem.7b02820. Epub 2017 Dec 28.

Authors

Takuya Hasegawa^{1

2}, Yusuke Abe³, Atsuya Koizumi³, Tadaharu Ueda^{1

2}, Kenji Toda³, Mineo Sato⁴

Affiliations

¹ Department of Marine Resources Science, Faculty of Agriculture and Marine Science, Kochi University , Nankoku 783-8502, Japan.
² Center for Advanced Marine Core Research, Kochi University , Nankoku 783-8502, Japan.
³ Graduate School of Science and Technology, Niigata University , 8050 Ikarashi 2-nocho, Niigata 950-2181, Japan.
⁴ Department of Chemistry and Chemical Engineering, Niigata University , 8050 Ikarashi 2-nocho, Niigata 950-2181, Japan.

PMID: 29283258
DOI: 10.1021/acs.inorgchem.7b02820

Abstract

Extensive attention has been focused toward studies on inexpensive and rare-earth-free garnet-structure vanadate phosphors, which do not have a low optical absorption due to the luminescence color being easily controlled by its high composition flexibility. However, bluish emission phosphors with a high quantum efficiency have not been found until now. In this study, we successfully discovered bluish-white emitting, garnet structure-based LiCa₃MV₃O₁₂ (M = Zn and Mg) phosphors with a high quantum efficiency, and the detailed crystal structure was refined by the Rietveld analysis technique. These phosphors exhibit a broad-band emission spectra peak at 481 nm under near UV-light excitation at 341 nm, indicating no clear difference in the emission and excitation spectra. A very compact tetrahedral [VO₄] unit is observed in the LiCa₃MV₃O₁₂ (M = Zn and Mg) phosphors, which is not seen in other conventional garnet compounds, and generates a bluish-white emission. In addition, these phosphors exhibit high quantum efficiencies of 40.1% (M = Zn) and 44.0% (M = Mg), respectively. Therefore, these vanadate garnet phosphors can provide a new blue color source for LED devices.