Single-phased white-emitting 12CaO•7Al2O3:Ce3+, Dy3+ phosphors with suitable electrical conductivity for field emission displays

A novel white-light-emitting phosphor, 12CaO center dot 7Al(2)O(3):Ce3+, Dy3+ with H- encaging, was prepared by the solid-state reaction in H-2 atmosphere. Upon excitation at 362 nm, the phosphor shows intense white-light emission that combines the blue and yellow emissions at 476 and 576 nm, assigned to the F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) transitions of Dy3+, respectively. A weak broad blue emission centered at 430 nm is also observed and attributed to the 5d-4f transitions of Ce3+. The photoluminescence intensity of Dy3+ increases greatly with increasing Ce3+ concentration, indicating that the effective energy transfer occurred from Ce3+ to Dy3+ in the phosphor. In particular, the phosphor can be converted to a persistent semiconductor upon ultraviolet irradiation due to the electrons released from the encaged H- ions, and the electrical conductivity is measured to be 10(-2) S cm(-1). The conductive phosphor exhibits excellent white-light emission (CIE coordinate of (0.324, 0.323)) under low-voltage (5 kV) electron beam excitation, suggesting that the phosphor is a potential candidate for applications in field emission displays.