Abnormal Self-Reduction Phenomenon of Europium-Doped Borate and Its Luminescence Properties

Abstract

In this work, mixed-valence Eu-doped Ba 2 AlB 4 O 9 Cl (BABOC) was successfully synthesized in an air atmosphere for the first time. The samples were determined to possess a good single phase by Rietveld structure refinement and X-ray powder diffraction (XRD). The luminescence spectra of the samples showed that the characteristic emission and excitation peaks of Eu 2+ and Eu 3+ were both present in the sample, and their emitting color could be adjusted by changing the Eu doping concentration. The band gap of BABOC, calculated by density functional theory (DFT), was found to be 4.70 eV and was confirmed by diffuse reflection spectroscopy (DRS). The relationship between the selfreduction efficiency of the sample and the doping concentration of Eu ions was studied by measuring the decay lifetimes of Eu 2+ and Eu 3+ . The thermal quenching and thermoluminescence spectroscopy of the samples were also studied in detail. All of the results indicated that BABOC:Eu has special self-reduction properties, and the abnormal self-reduction phenomenon was explained by a charge compensation model. Our investigation of BABOC:Eu provides practical evidence and a theoretical basis for the self-reduction phenomenon and a new method to further modify the luminescence properties of phosphors.

Oxygen vacancy content drives self-reduction and anti-thermal quenching

“…The deconvoluted high-energy peaks, centered at 531.36 eV in LZPM 0.14 and 531.40 eV in LZPM 0.14 -H, can be both ascribed to the presence of V O . 54,55 The same conclusion can be drawn from the EPR spectra of V O as well (Fig. 2c).…”

Crystal‐Field Engineering Control of an Ultraviolet–Visible‐Responsive Near‐Infrared‐Emitting Phosphor and Its Applications in Plant Growth, Night Vision, and NIR Spectroscopy Detection

“…Typically, pc‐LED devices are operated under high‐temperature conditions (≈150 °C), meaning that the high‐temperature fluorescence stability of the phosphor is an important factor in determining its applicability. [ 36 ] Figure a,b, respectively, show the fluorescence spectra of BaMgAl 10 O 17 :0.02Cr 3+ and BaMgGa 3 Al 7 O 17 :0.02Cr 3+ excited at 400 nm at different temperatures. As the temperature increased, the emission intensities of the two phosphors decreased, but the magnitude of the decrease in the case of BaMgGa 3 Al 7 O 17 :0.02Cr 3+ was significantly larger than that in the case of BaMgAl 10 O 17 :0.02Cr 3+ .…”

Multiple Coordination of Chromium Ion Luminescence: A Strategy for Designing Ultra-broadband NIR Long Persistent Luminescent Materials

“…Among them, peaks at 761 and 985 nm can be fitted by eq , and that at 692 and 848 nm can be fitted by eq responses to, respectively, combining the constituent components of each emission peak, 692 and 848 nm consist of three emission bands, and 761 and 985 nm consist of two emission bands, further indicating that the fitting results in Figure b are appropriate. Meanwhile, eq can be used to calculate the average lifetime of each peak position, as follows: For 761 and 985 nm, A 3 is 0. And the results are calculated as 26.3, 21.86, 19.36, and 17.56 μs for 692, 761, 848, and 985 nm, respectively, which also demonstrate the different sources of I 1 , I 2 , and I 3 .…”