Thermally stable Na3.6Y1.8(PO4)3:Eu3+ phosphor, luminescent properties and application in WLEDs

NASICON-type Na3.6Lu1.8−x(PO4)3:xEu3+ phosphors: structure and luminescence

“…Thus, the optimal concentration of Eu 3+ in NLPO: x Eu 3+ is higher than that in the isostructural Na 3.6 Y 1.8 (PO 4 ) 3 : x Eu 3+ ( x = 0.3). 14…”

“…Thus, the optimal concentration of Eu 3+ in NLPO:xEu 3+ is higher than that in the isostructural Na 3.6 Y 1.8 (PO 4 ) 3 :xEu 3+ (x = 0.3). 14 The decrease of luminescence intensity at x > 0.5 is due to concentration quenching. The critical distance between the neighbouring Eu 3+ ions will be calculated on the basis of the data presented in Fig.…”

“…The emission intensity ratio of the 5 D 0 → 7 F 2 and 5 D 0 → 7 F 1 transitions is 1.74, indicating that Eu 3+ ions are located in non-inversion sites in the phosphate host. 14,31 Thus, it is suggested that the site symmetry differs from a centrosymmetric structure.…”

“…A similar conclusion on the quenching mechanism origin has been drawn for Na 3.6 Y 1.8−x (PO 4 ) 3 :xDy 3+ (θ = 5.76) 15 and Na 3.6 Y 1.8−x (PO 4 ) 3 :xEu 3+ (θ = 4.03). 14 The temperature dependence of the Eu 3+ emission intensity under intracentre excitation in two excitation lines peaking at 395 nm (3.14 eV) and 384 nm (3.23 eV) is presented for NLPO: xEu 3+ in Fig. 6a.…”

“…The substitution of Sc cations with other rare earth elements may also influence energy transfer processes to emission centers as well as the quantum efficiency of these centers. In particular, novel phosphate-based Na 3.6 Y 1.8 (PO 4 ) 3 :Eu 3+ 13,14 and Na 3.6 Y 1.8 (PO 4 ) 3 :Dy 3+ 15 phosphors have also demonstrated high temperature stability. However, for other NASICON-type phosphors the effect has not been observed so far 16–18 and the role of structural disorder in thermal stability enhancement requires further studies.…”