Structure and photoluminescence of Eu(3+) doped Sr(2)InTaO(6) red phosphor with high color purity

The Eu(3+)-doped Sr(2)InTaO(6) phosphors were obtained by solid-state reaction method and the phase purity of Sr(2)InTaO(6):Eu(3+) samples were investigated by the XRD patterns. The Rietveld refinements were conducted to further obtain crystal structure information and the results indicate Sr(2)InTaO(6):Eu(3+) samples crystallized in the monoclinic system with a P(121) space group. The optical band gap of Sr(2)InTaO(6) was calculated to be 3.84 eV by the diffuse reflectance spectra, which are consistent with the result (3.823 eV) of density functional theory. Under 396 nm excitation, the Sr(2)InTaO(6):Eu(3+) phosphor showed a red photoluminescence band centered at about 624 nm due to the (5)D(0) → (7)F(2) transition. Monitored at 624 nm, the phosphors showed two wide bands from 200 nm to 500 nm, which originated from the charge-transfer band of Eu(3+)–O(2−) and f–f transitions of Eu(3+) ions. The optimum luminous concentration is 0.12 because of the concentration quenching determined to be a quadrupole–quadrupole interaction. The luminescence decay lifetimes of the Sr(2)InTaO(6):Eu(3+) phosphors were milliseconds. Significantly, the temperature-dependent emission spectra of Sr(2)InTaO(6):0.12Eu(3+) phosphors exhibited good thermal stability and the CIE chromaticity coordinates of Sr(2)InTaO(6):0.12Eu(3+) were (0.6265, 0.3693) with high color purity. The present work demonstrated that the Sr(2)InTaO(6):Eu(3+) red-emitting phosphors show great application in lighting technology.