Three series of new ultraviolet-emitting Ca9Y(PO4)(7):Ln(3+) (Ln = Ce, Gd, Pr) phosphors were synthesized, and their luminescence was investigated. Under vacuum ultraviolet excitation Ca9Y(PO4)(7):Ce3+ phosphors emit UVA light with one broad emission centered at 346 nm, on account of the 5d(1)-> 4f(1) transition of Ce3+ ions; the optimal doping concentration of these phosphors is 0.2 mol. Ca9Y(PO4)(7):G(3+) phosphors show a strong 4f(7)-> 4f(7) transition and a sharp UVB, emission band at 312 nm; the optimal doping concentration of these phosphors is 0.7 mol. The PL spectra of Ca9Y(PO4)(7):Pr3+ show two broad UVC emission bands centered between 230 and 340 nm, owing to the 4f(1)5d(1)-> 4f(2) transition of Pr3+ ions; the optimal, doping concentration of these phosphors is 0.2 mol. Under 172 nm excitation, we found that the luminescence intensity of the UVA-emitting Ca9Y(PO4)(7):0.2Ce(3+) is 0.3675 times that of BaSi2O5:0.05Pb(2+), that of the UVB-emitting Ca9Y(PO4)(7):0.7Gd(3+) is 1.7 times that of YAl3(BO3)(4):0.25Gd(3+), and that of the UVC-emitting Ca9Y(PO4)(7):0.2Pr(3+) is 1.5 times that of LaPO4:0.1Pr(3+). The thermal stability investigation indicated that the luminescence decay was only 9.2%, 18.2%, and 10.3% for Ca9Y(PO4)(7):0.2Ce(3+); Ca9Y(PO4)(7):0.7Gd(3+), and Ca9Y(PO4)(7):0.2Pr(3+) at 250 degrees C relative to that at ambient temperature, respectively. The Ca9Y(PO4)(7):Ln(3+) (Ln = Ce, Gd, Pr) phosphors exhibit high emission efficiency and excellent thermal stability.