Photoluminescence Characteristic of Gallate-based Red Emitting Phosphors with High Color Purity

Abstract

<TEX>$Eu^{3+}$</TEX>-activated <TEX>$R_3GaO_6$</TEX> (R = Y, Gd) phosphors were prepared in a conventional solid-state reaction and their optical properties were investigated. These compounds exhibit strong red emission under light excitation at 254 nm. The emission spectra are dominated by peaks appearing around 610-630 nm that are induced by the electric dipole transition of <TEX>$^5D_0\;{\rightarrow}\;^7F_2$</TEX> of <TEX>$Eu^{3+}$</TEX>. In addition, the appropriate CIE (Commission Internationale de l'clairage) chromaticity coordinates, (x = 0.656, y = 0.336) for <TEX>$Y_3GaO_6$</TEX> and (x = 0.655, y = 0.334) for <TEX>$Gd_3GaO_6$</TEX>, become closer to the NTSC (National Television System Committee) standard values. With the optimized activator concentrations, the maximum emission brightness is approximately 80% of <TEX>$Y_2O_3$</TEX>:<TEX>$Eu^{3+}$</TEX> typical red-emitting phosphor with improved color purity under an excitation condition of 254 nm.