Synthesis, Photoluminescence and Thermoluminescence Properties of Sm³⁺and Dy³⁺Ions Doped Barium Gadolinium Titanate Ceramics

Effect of Partial Ca2+ Substitution with Ln3+ (Ln = Y, La) on Luminescence Enhancement of Ca18.62Zn2(PO4)14:0.38Dy3+ White-Emitting Phosphor for White Light-Emitting Diodes

“…The emission spectra (λ ex = 348 nm) of Ca 18.62– x Ln x ­Zn 2 ­(PO 4 ) 14 :0.38Dy 3+ (Ln = Y, La) are displayed in Figure b and c, and as expected, the intensity of the emission peak will only be changed after Ln 3+ ion doping. The luminescence spectra of the prepared samples contain three main emission peaks located in the blue (484 nm), yellow (575 nm), and red (665 nm) regions, originating from the magnetic dipole transition 4 F 9/2 → 6 H 15/2 , electric dipole leap 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 transitions of Dy 3+ , respectively . The luminescence intensity of Ca 18.62– x Ln x ­Zn 2 ­(PO 4 ) 14 :0.38Dy 3+ becomes stronger compared with that of the Ca 18.62 Zn 2 ­(PO 4 ) 14 :0.38Dy 3+ samples as the Ln 3+ substitution amount increases, and shows a trend of strengthening first and then weakening.…”

“…The luminescence spectra of the prepared samples contain three main emission peaks located in the blue (484 nm), yellow (575 nm), and red (665 nm) regions, originating from the magnetic dipole transition 4 F 9/2 → 6 H 15/2 , electric dipole leap 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 transitions of Dy 3+ , respectively. 41 The luminescence intensity of Ca 18.62−x Ln x Zn 2 (PO 4 ) 14 :0.38Dy 3+ becomes stronger compared with that of the Ca 18.62 Zn 2 (PO 4 ) 14 :0.38Dy 3+ samples as the Ln 3+ substitution amount increases, and shows a trend of strengthening first and then weakening. For Ca 18.62−x Ln x Zn 2 (PO 4 ) 14 :0.38Dy 3+ samples, when x = 0.57 (Y) and x = 0.76 (La), the Ln partially substituted phosphors show the optimal luminescence intensity, which is 1.43 times and 1.55 times the luminescence intensity of the Ca 18.62 Zn 2 (PO 4 ) 14 :0.38Dy 3+ phosphor.…”

Ceramics in Archaeology

“…TL dating is based on the fact that when clay and other geological inclusions in pottery are fired at temperatures of 500 C or higher, electrons which had been 'trapped' in the crystal lattice structure are freed, emitting light or thermoluminescence (Raju et al, 2014). Following the firing process, new trapped electrons gradually accumulate in the crystalline imperfections of the pottery, as a natural consequence of radioactive decay.…”