[Near-infrared luminescence and energy transfer of ACaPO4 : Eu2+, Nd3+ (A = Li, K, Na)].

: Near-infrared (NIR) luminescence phosphors ACaPO4 : Eu2+, Nd2+ (A = Li, K, Na) were prepared by conventional solid state method and the sensitization of Nd3+ near-infrared luminescence by Eu2+ was investigated. The characteristic NIR luminescence of Nd3+ in ACaPO4 matrix is greatly enhanced by co-doping of Eu2+. The fluorescence properties of ACaPO4 : Eu2+, the NIR luminescence properties of ACaPO4 : Eu2+, Nd3+ and the fluorescence lifetime were studied. The effect of emission wavelength of Eu2+ on NIR luminescence of Nd3+ was investigated; The energy transfer mechanism between Eu2+ and Nd3+ was also discussed. Emission peak wavelength of Eu2+ In ACaPO4 matrixes was found red shift with the series of A = Li, K, Na and the extent of the overlap with the different excitation peaks of Nd3+ changes obviously. It was concluded that the emission peak position of Eu2+ is a very important factor for energy transfer, and the optimal wavelength range for Eu2+ --> Nd3+ energy transfer is 500 to 550 nm.