Abstract: A series of single-phase long afterglow phosphors Ca_(1-x-y)Al₂O₄:Eu²⁺_x,Nd³⁺_y(0≤x≤0.045,(0≤y≤0.0037)) were prepared by the traditional solid state reaction method and their photoluminescence were investigated.Intense blue emission of the samples was observed with a broad band peak at about 440 nm,which is due to the 4f ⁶5d→4f ⁷ transition of Eu²⁺.The effect of different rare earth contents on the afterglow properties was investigated and the optimum content of Eu²⁺ and Nd³⁺ are x=0.001 25 and y=0.002 5 respectively.Initial brightness and persistent afterglow time of the corresponding sample is over 1 200 mcd/m² and more than 1 000 min.60 min later,its brightness is still over 10 mcd/m².Thermoluminescence and positron annihilation methods were used to investigate the effect of Nd³⁺and Eu²⁺ co-doping on their luminescent properties.

Key words: Long afterglow, CaAl₂O₄:Eu²⁺,Nd³⁺, Positron annihilation