Temperature effect on the photoluminescence intensity and Eu2+ excited state lifetime in EuGa2S4 and EuGa2S4:Er3+

Luminescence properties of stoichiometric EuM2S4 (M = Ga, Al) conversion phosphors for white LED applications

“…The lifetime value of Eu 2+ in the EuGa 2 S 4 is comparable to the reported value 0.055 µs in Ref. 18. Similarly, the stoichiometric Eu 2 SiS 4 has a main decay constant of about 0.045 µs at room temperature 24.…”

“…In the present case, the lowest absorption energy of E abs is about 2.56 eV (485 nm) and the Stokes shift (Δ S ) is calculated to be 0.28 eV (2255 cm −1 ). The Stokes shift value in this work is compared with the reported value of 0.29 eV in the literature 18. Knowing the value of E abs allows us to determine the red shift D of the f–d transition with respect to the free ion ( E free = 4.19 eV for Eu 2+ ) 22.…”

“…The PL and PLE spectra of the EuGa 2 S 4 phosphor are essentially similar to those of SrGa 2 S 4 :Eu 2+ ( λ em = 535 nm, FWHM = 49 nm), although there are small differences in the peak wavelengths and half‐widths of the PL spectra. The resemblance of the two spectra indicates that the emission process of EuGa 2 S 4 is due to a phonon‐terminated transition of the Eu ion 18. The lattice constants of these compounds are close (EuGa 2 S 4 : 20.72 Å, 20.40 Å, 12.20 Å; SrGa 2 S 4 : 20.05 Å, 20.41 Å, 12.12 Å), and the lattice structure of EuGa 2 S 4 is considered to be the same as that of SrGa 2 S 4 2.…”

“…Structurally, EuGa 2 S 4 crystallizes into an orthorhombic structure in the space group D‐Fddd with lattice parameters a = 20.72 Å, b = 20.40 Å, and c = 12.20 Å 18. In EuGa 2 S 4 , Eu atoms are surrounded by eight S atoms and with three different symmetry sites: two D 2 and one C 2 ; Ga atoms are located in the centers of the tetrahedrons formed by four S atoms.…”

Investigation of the phenomenon of current transition EuGa-=SUB=-2-=/SUB=-S-=SUB=-4-=/SUB=-:Er-=SUP=-3+-=/SUP=- crystals

“…Europium tetrachalcogenides EuGa 2 S 4 from group AB III 2 C VI 4 (A -Eu, Yb, Dy; B -Ga, In; C -S, Se, Te) with an incomplete inner 4 f shell, which are activated by rare-earth elements (specifically, erbium), have been studied extensively since the moment of their synthesis, and several intriguing physical properties have been revealed in the process. A considerable number of papers [1][2][3][4][5][6] focused on the photo-, electro-, and thermoluminescence properties of these crystals have already been published. The results of experiments performed in these studies provided an opportunity to determine certain key parameters of photoluminescence (red shift, Stokes shift, lifetime of Er 3+ ions, etc.…”