Effect of Dopant Concentrations on the Luminescent Properties of LiAl₅O₈:Fe Phosphors

Abstract

The structural and optical properties of pure and Fe‐doped LiAl5O8 are investigated using the modified sol–gel method, using anhydrous glucose as the polymerizing agent. The structural and optical properties are identified using X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and X‐ray excited optical luminescence (XEOL). The XRD diffraction patterns confirm the formation of a LiAl5O8 phase with different Fe concentrations. The effect of Fe3+ ions as a dopant on the luminescent properties of LiAl5O8 is studied and is discussed in detail. The results reveal a red emission upon excitation at 267 and 391 nm. A maximum emission intensity is observed for 1 mol% of Fe. PL and XEOL emission spectra exhibit 4T1g(4 G) → 6A1g(6S) and 4E1g + 6A1g(4 G) → 6A1g(6S) transitions typical of the Fe3+ ion. In addition, an 2 E → 4A2 transition centered at ≈714 nm is attributed to the presence of Cr3+ ions in the host lattice as a contaminant in starting materials. The coordinated Commission Internationale de l'Eclairage (CIE) is calculated from the emission spectra, and points to the possibility of applying this study as a red–pink emitting match.

Fe3+‐activated magnetoplumbite persistent luminescence phosphor by modulating the oxygen vacancy

“…The decay behaviour of the Fe 3+ -doped SGO sample, measured for the emission at 813 nm, is shown in Figure 3d. The characteristic PL lifetime for Fe 3+ ion in the SGO sample was determined to be 22.5 μs, which is close to the typical value of Fe 3+ ion PL lifetime observed in other materials, such as LiAl 5 O 8 crystal [28].…”

Structural confinement toward suppressing concentration and thermal quenching for improving near-infrared luminescence of Fe3+

“…S3, † the emission intensity of 50% and 100% Fe 3+ -doped samples can be maintained at 73.46% and 18.25% that of the 20% Fe 3+ -doped phosphor, respectively. In general, the optimal Fe 3+ -dopant concentration in previously reported phosphors is relatively small, such as 0.3%, 1% and 2% in ZnGa 2 O 4 , LiAl 5 O 8 and NaScSi 2 O 6 , 16,18,28 respectively. The suppressed luminescence concentration quenching in Fe 3+ -doped SGP phosphors is closely related to the unique structural characteristic of SGP.…”

“…17 Similar to Cr 3+ ions, the emission wavelength of Fe 3+ ions can be easily tuned because the bare 3d electrons are susceptible to the host environment. 18 However, the d–d transition of Fe 3+ ions is strictly restricted by the Laporte selection rule, especially in highly symmetric fields, 14,19 and moreover suffers from a strong electron–phonon coupling effect, leading to the poor luminescence property of Fe 3+ ions. Several strategies have been proposed to enhance Fe 3+ luminescence.…”