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新发表了一篇论文https://pubs.rsc.org/en/content/articlelanding/2020/dt/d0dt00931h#!divAbstract
Mn4+在MgAl2O4中表现出峰值为651 nm的超宽红光发光谱。2Eg-4A2g的跃迁表现为651 nm,这是目前在铝酸盐基质中最短的发光波长。其发光光谱半高宽很宽,应与镁铝尖晶石中所含anti-site disorder有很大关系。
Abstract:
Blue light pumped red luminescence with broadband and high photon-energy
emission is highly desired for phosphor-converted white light-emitting
diodes (LEDs), to achieve high color rendering index and high luminous
efficacy. The Mn4+-doped red-emitting phosphors generally exhibit sharp
vibrionic emissions associated with the parity and spin-forbidden 2Eg →
4A2g transition. In this paper, two abnormal luminescence behaviors were
observed for Mn4+ in the MgAl2O4:Mn4+ spinel phosphor with a short
wavelength emission peaking at 651 nm. Firstly, the Mn4+ 2Eg → 4A2g
transition exhibits an ultrabroadband luminescence band in MgAl2O4 and
the large full-width at half-maximum (FWHM) is dependent both on the
calcination temperature and the partial substitution of Al3+ with Ga3+. Secondly, the thermal quenching behavior of the Mn4+ 2Eg → 4A2g
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 antisite 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 verified 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+ 2Eg → 4A2g transition.
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