Deep-red emission of Mn4+ and Cr3+ in (Li1−xAx)2MgTiO4 (A=Na and K) phosphor: Potential application as W-LED and compact spectrometer

Abstract

Mn 4+ doped and Mn 4+ /Cr 3+ co-doped alkali metal titanate phosphors have been prepared by solid state reaction method. A part of Li + ions in the Li 2 MgTiO 4 : Mn 4+ are substituted with Na + and K + ions and consequently the intensity of Mn 4+ emission at 678 nm is enhanced by 1.7 and 2.5 times, respectively. In the Mn 4+ /Cr 3+ co-doped (Li 0.95 K 0.05) 2 MgTi 0.999 O 4 , both emission of Cr 3+ at 726 nm and emission of Mn 4+ at 678 nm of Mn 4+ are observed. It is interesting to find that the intensity ratio of 726 nm to 678 nm emissions in the Mn 4+ /Cr 3+ phosphor continually increases with excitation wavelength increasing from 290 nm to 455 nm, which means that the intensity ratio in turn can be used to identify the excitation light wavelength. This refers a possible approach to design novel compact light-wavelength detector or spectrometer based on the phosphor. The mechanism of Na + or K + substitution induced luminescence enhancement in the Mn 4+ phosphor and the competition between the Cr 3+ and Mn 4+ emissions in the Mn 4+ /Cr 3+ co-doped has been discussed.

Bandshift Luminescence Thermometry Using Mn4+:Na4Mg(WO4)3 Phosphors

“…Indeed, no narrow bands or fine spectral features are observed in the emission spectra of Na 4 Mg 1−2x Mn x (WO 4 ) 3 phosphors even at 78 K. In addition, metal−oxygen bond distances for the Na0/Mg/Mn site are significantly longer than those reported for the few Mn 4+ -activated phosphors for which asymmetric and broadened vibronic emission from the 2 E state is observed (type B phosphors in the classification proposed by Adachi 25 ); these are Li 2 Mg 2 Ti 3 O 8 (1.90−2.02 Å) 26 and Li 2 MgTiO 4 (2.08 Å). 27 Longer metal−oxygen distances lead to a weaker crystal field and, 28 ultimately, to broadband red emission from Mn 4+ . 29−32 Emission intensities increase up to x = 0.030 and then decrease due to concentration quenching (see inset of Figure 5a).…”

Review—Mn4+-Activated Red and Deep Red-Emitting Phosphors

“…Almost all the PL studies on type O-B phosphors were performed from room temperature up to 500 K, but not at any temperatures lower than room temperature. [107][108][109][110] These studies reported no clear change in the PL spectral feature from room temperature to 500 K and, as a result, did not enable to explicitly determine the ZPL emission energies in such phosphors. Only a study by Jin et al 31 performed PL measurements from T = 77 to 500 K. However, any fine structure characterizing the ZPL emission transition of type O-B phosphor was not observed in the PL spectra even at 77 K. Therefore, we estimate the ZPL emission energies 2 E g for type O-B phosphors by analyzing the room-temperature PL spectra and assuming a Poisson distribution function of Eq.…”

Photoluminescence Properties of Mn4+, Cr3+ co-doped BaMgAl10O17 Phosphor

“…In the range of 320-400 nm and 490-530 nm, R increases with the excitation wavelength increasing, while R decreases as the excitation wavelength increase in the range of 400-480 nm. Due to the unique properties, the BMA: Mn 4+ , Cr 3+ samples can be used in wavelength detection in a certain wavelength range because the excitation wavelength might be obtained by calculating the emission intensities of Mn 4+ and Cr 3+ to obtain the integrated intensity ratio R. 33 Absolute sensitivity S a for the wavelength detection is calculated by Eq. 8: Relative sensitivity S r is expressed by Eq.…”