Issue 17, 2020

Ultrabroadband red luminescence of Mn4+ in MgAl2O4 peaking at 651 nm

Abstract

Blue light pumped red luminescence with broadband and high photon-energy emission is highly desired for phosphor-converted white light-emitting diodes (pc-wLEDs), to achieve a high color rendering index and high luminous efficacy. Mn4+-doped red-emitting phosphors generally exhibit sharp vibronic emissions associated with the parity- and spin-forbidden 2Eg4A2g transitions. In this paper, two abnormal luminescence behaviors were observed for Mn4+ in the MgAl2O4:Mn4+ spinel phosphor with a short wavelength emission band peaking at 651 nm. Firstly, the Mn4+ 2Eg4A2g transition exhibits ultrabroadband luminescence in MgAl2O4 and the large full-width at half-maximum (FWHM) is dependent both on the calcination temperature and on the partial substitution of Al3+ with Ga3+. Secondly, the thermal quenching behavior of the Mn4+ 2Eg4A2g luminescence in MgAl2O4 shows a dependence on its thermal treatment and preparation method. The Rietveld refinement and Raman results demonstrate that the variation in the FWHM of the luminescence spectra is a sum effect of structural ordering (i.e., isotropic displacement decrease of constituent atoms) and the Mg ↔ Al anti-site disorder. A model for the observed varying thermal quenching of luminescence was tentatively proposed. The intrinsic thermal quenching temperature of Mn4+ luminescence in MgAl2O4 was found to be 390–400 K using the samples prepared by the co-precipitation and molten salt methods. The present work gives a novel perspective to understand the luminescence spectra of Mn4+ 2Eg4A2g transition.

Graphical abstract: Ultrabroadband red luminescence of Mn4+ in MgAl2O4 peaking at 651 nm

Supplementary files

Article information

Article type
Paper
Submitted
12 Mar 2020
Accepted
06 Apr 2020
First published
10 Apr 2020

Dalton Trans., 2020,49, 5711-5721

Ultrabroadband red luminescence of Mn4+ in MgAl2O4 peaking at 651 nm

H. Ji, X. Hou, M. S. Molokeev, J. Ueda, S. Tanabe, M. G. Brik, Z. Zhang, Y. Wang and D. Chen, Dalton Trans., 2020, 49, 5711 DOI: 10.1039/D0DT00931H

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