Photoluminescent properties and energy transfer mechanism of Tb3+-Ce3+ doped CaSi2O2N2 oxynitride phosphors

Bi3+ and Eu3+ Activated Luminescent Behaviors in Non-Stoichiometric LaO0.65F1.7 Structure

“…( Materials 2019, 12, x FOR PEER REVIEW 5 of 9 concentration of Bi 3+ and Eu 3+ ions, with α = 6, 8, or 10, corresponding to dipole-dipole, dipolequadrupole, and quadrupole-quadrupole interactions, respectively, in accordance with Dexter theory [10,[22][23][24]32]. In Figure 4b, when α = 6, 8, and 10, the linear plots showed energy transfer from the Bi 3+ to Eu 3+ ions with R 2 = 0.9635, 0.9894, and 0.9982 in the La0.94Bi0.01Eu0.05O0.65F1.7 phosphors, respectively.…”

“…The emission of Eu 3+ transitions was maximized when the Eu 3+ content in the La 0.99−q Bi 0.01 Eu q O 0.65 F 1.7 (q = 0-0.1) phosphors was q = 0.05. The energy transfer mechanism could be represented by linear plots of I SO /I S versus C Bi-Eu α/3 , where C Bi-Eu is the concentration of Bi 3+ and Eu 3+ ions, with α = 6, 8, or 10, corresponding to dipole-dipole, dipole-quadrupole, and quadrupole-quadrupole interactions, respectively, in accordance with Dexter theory [10,[22][23][24]32]. In Figure 4b, when α = 6, 8, and 10, the linear plots showed energy transfer from the Bi 3+ to Eu 3+ ions with R 2 = 0.9635, 0.9894, and 0.9982 in the La 0.94 Bi 0.01 Eu 0.05 O 0.65 F 1.7 phosphors, respectively.…”

“…where V is the volume of the La 0.99 Bi 0.01 O 0.65 F 1.7 unit cell, N is the number of available La 3+ sites for the dopant in the unit cell, m c is the critical concentration of Bi 3+ , and R c is the critical distance for energy transfer [10,[22][23][24]32]. When N and V are 1 and 97.75 Å 3 , respectively, for La 0.99 Bi 0.01 O 0.65 F 1.7 , R c (m c = 0.01) is 26.53 Å.…”

“…where I S and I SO are the luminescence intensities of the Bi 3+ sensitizer in the presence and absence of a Eu 3+ activator, respectively [10,[22][23][24]32]. The emission of Eu 3+ transitions was maximized when the Eu 3+ content in the La 0.99−q Bi 0.01 Eu q O 0.65 F 1.7 (q = 0-0.1) phosphors was q = 0.05.…”

“…The Ce 3+ ions emit in the blue to yellow wavelength regions assigned by 5d 1 to 4f 1 transitions when excited by ultraviolet (UV) to visible radiation in various host lattices [6][7][8][9]. The Ce 3+ ion, as a donor, enables efficient energy transfer, improving the emission from acceptors, such as Tb 3+ or Mn 2+ ions in the host structures [10][11][12][13][14][15][16][17][18]. The Bi 3+ ion is an active luminescent center emitting blue to green light assigned to 6s 1 6p 1 to 6s 2 transitions when excited by UV to near UV wavelength regions in host lattices [19][20][21].…”