Photoluminescence and afterglow of Dy(3+) doped CaAl(2)O(4) derived via sol–gel combustion

With doping concentration varying from 0.1 to 5.0 mol%, a series of Dy(3+) doped calcium aluminate (CaAl(2)O(4):Dy(3+)) phosphors were synthesized via a sol–gel combustion technique. The phase, morphology, photoluminescence (PL), afterglow, and thermoluminescence (TL) glow curves of CaAl(2)O(4):Dy(3+) were investigated by means of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, PL spectroscopy, afterglow spectroscopy, and TL dosimetry, respectively. It is found that: (i) oxygen vacancies and Dy(3+) work as two independent sets of luminescence centers of PL for CaAl(2)O(4):Dy(3+); (ii) Dy(3+) works as the luminescence center of afterglow for CaAl(2)O(4):Dy(3+); (iii) the afterglow of CaAl(2)O(4):Dy(3+) lasts for about 115 min at the optimal doping concentration of around 0.8 mol%; and (iv) multiple traps, which are sensitive to doping concentration, are present in CaAl(2)O(4):Dy(3+). The PL and afterglow mechanisms of CaAl(2)O(4):Dy(3+) are discussed to reveal the processes of charged carrier excitation, migration, trapping, detrapping, and radiative recombination in CaAl(2)O(4):Dy(3+).