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.