Thermal stability of the luminescence of Ca sub(6)Ba(PO sub(4)) sub(4)O:Eu super(2+) yellow phosphor for white light-emitting diodes

Yellow-emitting Ca sub(6)Ba(PO sub(4)) sub(4)O:Eu super(2+) phosphors were synthesized by solid-state reaction method. The phase composition was checked by X-ray powder diffraction. The photoluminescence properties of Ca sub(6)Ba(PO sub(4)) sub(4)O:Eu super(2+) and their thermal properties of photoluminescence were explored. The excitation spectra ranging from 230 to 450 nm and an intense broad yellow emission band centered at 530 nm can be observed under the excitation at 375 nm. Ca sub(6)Ba(PO sub(4)) sub(4)O:0.07Eu super(2+) phosphor maintains 45 % of the photoluminescence intensity of room temperature when heated up to 150 degree C, exhibiting a relatively good thermal quenching resistance. The optimum concentration of Eu super(2+) in Ca sub(6-x )Ba(PO sub(4)) sub(4)O:xEu super(2+) was found with x = 0.07, and the concentration quenching mechanism was illustrated by configurational coordinate diagram. The luminescence decay of Eu super(2+) ions was also studied carefully, showing the decrease of the lifetime with the increase of Eu super(2+) concentration.