XRD patterns of LiBa1−x PO4:xRE phosphors with (a) RE = Eu2+, x = 0.05; (b) RE = Tb3+, x = 0.40; (c) RE = Sm3+, x = 0.06; and JCPDS card No. 14-0270; some weak peaks (#) and (*) are due to the materials BaO and LiSrPO4, respectively.
Emission spectra of LiBaPO4 activated by (a) RE = Eu2+, (b) RE = Tb3+, and (c) RE = Sm3+ shown as a function of different activator concentrations measured at room temperature. The inset shows excitation spectra of maximum intensity observed for the activators.
(Color online) The CIE 1931 chromaticity diagram of LiBa1-x PO4:xRE (RE = Eu2+, Tb3+, Sm3+) phosphors under various excitation wavelengths.
(Color online) The PL decay curves of (a) Eu2+ emission (at 470 nm) under excitation in the 4f → 5d absorption band of the Eu2+ ion (370 nm), (b) Tb3+ emission (at 545 nm) under excitation in the 5D4 → 7F5 absorption band of the Tb3+ ion (370 nm), and (c) Sm3+ emission (at 545 nm) under excitation in the 4G5/2 → 6H7/2 absorption band of Sm3+ ion (370 nm). The inset shows decay time vs activation concentration of LiBaPO4 with different dopants.
(Color online) (a) PL spectra excited at 350 nm of LiBa0.95PO4:0.05Eu2+ phosphor for various temperatures; the inset shows temperature-dependent relative emission intensity of LiBa0.95PO4:0.05Eu2+. (b) Activation energy for thermal quenching of LiBa0.95PO4:0.05Eu2+.
(Color online) PL spectra of (a) LiBa0.60PO4:0.40Tb3+ and (b) LiBa0.94PO4:0.06Sm3+ for various temperatures; the two insets show the corresponding integrated emission intensity at different temperatures.
(Color online) (a) Part of the energy levels scheme of LiBaPO4 doped with Tb3+, and Sm3+. (b) Schematic configurational coordinate diagrams that present possible mechanisms of temperature-dependent emission of Sm3+ in the LiBaPO4 host.
CIE chromaticity coordinates of RE-doped LiBaPO4 (RE = Eu2+, Tb3+, Sm3+).
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