UV excitation and trapping centers in CaTiO3:Pr3+

The influence of defects formed by Ca excess and thermal post-treatments on the persistent luminescence of CaTiO_3:Pr

“…The emission spectra are dominated by the red emission at 612 nm, which corresponds to the transition for 1 D 2 to 3 H 4 ground state. The excitation spectra present three bands, which are in agreement with previously reports in bibliography [12]. The A band (~330 nm) presents no changes in the intensity, while B (~360 nm) and C (~280 nm) exhibit clear changes in the relative intensities.…”

“…5 and illustrates that all samples with Ca excess exhibit longer decay time than the stoichiometric one. As previously explained, the incorporation of CaO defects in the CaTiO 3 structure can induce the formation of oxygen vacancies [20] which can act as electron traps and increase the decay time in the persistent luminescence [12]. Remarkable is the maximum decay time at 3% of Ca excess.…”

“…The most efficient materials for persistent luminescence are in the blue-green region, such as SrAl 2 at 615 nm is close to the "ideal red" (chromaticity coordinates x = 0.680 and y = 0.311) according to the International Commission on Illumination (CIE) [11]. Also its moderate intrinsic conductivity [12] and resistance to highdensity electron irradiation [13] make it ideal for its use in flat panel displays (FPD).…”

“…Ca excess can also be introduced in the lattice by another mechanism, in this case, the Ca and O are placed in its crystallographic site and Ti and O vacancies are formed [20]. This last mechanism should have a stronger influence on the persistent luminescence because oxygen vacancies can act as traps and increase the decay time [12].…”

Luminescent properties of Li2 (Ca0.99, Eu0.01) SiO4: B3+ particles as a potential bluish green phosphor for ultraviolet light-emitting diodes

“…The optimum ratio of reactants can make the combustion reaction more complete and benefit the formation of crystalline particles. The minor amount of H 3 BO 3 was introduced as flux in the experiment, since it was proved to be effective in stimulating host-lattice formation and grain growth in some studies [21][22][23][24]. The molar ratio of boric acid to calcium nitrate was varied from 0 to 0.12.…”