Novel red-emitting garnet Na2CaTi2Ge3O12: Pr3+,Na+ phosphors

A series of red-emitting garnet Na2CaTi2Ge3O12: Pr3+, Na+ phosphors were synthesized by a high-temperature solid-state reaction. The crystal structure, luminescence properties, decay lifetime, and thermal stability were initially studied. The excitation spectra show one broad band centered at 337 nm and several sharp bands centered at 451, 462, 474 and 488 nm, which are ascribed to the 4f(2) -> 4f(1)5d(1) and 4f(2) -> 4f(2) transitions of Pr3+. The emission spectra show narrow band emissions centered at 595, 609, 622 and 630 nm, which correspond to the parity-forbidden intra-configuration 4f2 -> 4f2 transitions of the Pr3+ ion. The optimum concentration of Pr3+ in Na2CaTi2Ge3O12: Pr3+, Na+ was determined to be 2 mol%. Upon excitation at 451 nm, the Na2CaTi2Ge3O12: Pr3+, Na+ phosphors exhibit an intense red emission at 609 nm with CIE chromaticity coordinates of ( 0.6524, 0.3457). The wider color gamut of the as-synthesized Na2CaTi2Ge3O12: Pr3+, Na+ is much higher than that of commercially available materials, such as (CaSiN8)-N-5: Eu2+ and CaAlSiN3: Eu2+. The results indicate that the novel red-emitting phosphors could be a potential candidate for display applications.