Structure and photoluminescence of Eu doped SrInTaO red phosphor with high color purity.

The Eu-doped SrInTaO phosphors were obtained by solid-state reaction method and the phase purity of SrInTaO:Eu samples were investigated by the XRD patterns. The Rietveld refinements were conducted to further obtain crystal structure information and the results indicate SrInTaO:Eu samples crystallized in the monoclinic system with a space group. The optical band gap of SrInTaO 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 SrInTaO:Eu phosphor showed a red photoluminescence band centered at about 624 nm due to the D → F 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-O and f-f transitions of Eu 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 SrInTaO:Eu phosphors were milliseconds. Significantly, the temperature-dependent emission spectra of SrInTaO:0.12Eu phosphors exhibited good thermal stability and the CIE chromaticity coordinates of SrInTaO:0.12Eu were (0.6265, 0.3693) with high color purity. The present work demonstrated that the SrInTaO:Eu red-emitting phosphors show great application in lighting technology.