Novel red-emitting perovskite-type phosphor CaLa1-xMgM'O6: xEu3+ (M' = Nb, Ta) for white LED application

Single phase of CaLa1-xMgM'O6: xEu3+ (M' = Nb, Ta; 0 < x [el] 1) red phosphors was prepared by solid-state reaction method, and their structural and optical properties were also investigated in detail. The excitation spectra of CaLa1-xMgM'O6: xEu3+ revealed two excitation bands at 396 and 466 nm, which correspond to the sharp 7F0 arrow right 5L6 and 7F0 arrow right 5D2 transitions of Eu3+ and matches well with the two popular emissions from near-UV and blue light-emitting diode (LED) in solid-state lighting technology. The intensity of the red emission for Ca(La0.7Eu0.3)MgTaO6 and Ca(La0.6Eu0.4)MgNbO6 are respectively three and four times higher than that of (Y0.95Eu0.05)2O3 under near-UV light irradiation, while under blue light irradiation are 2 and 2.5 times respectively. The quantum efficiencies of the entitled phosphors excited under 396 and 466 nm are also investigated and compared with commercial phosphors Y2O3: Eu3+, Sr2Si5N8: Eu2+ and Y3A5G12: Ce3+. The chromaticity coordinates of Ca(La0.7Eu0.3)MgTaO6 and Ca(La0.6Eu0.4)MgNbO6 (x = 0.662, y = 0.338) are close to the standard of National Television Standard Committee (NTSC) values (x = 0.670, y = 0.330).