A direct warm-white-light CaLa 2 (MoO 4) 4 : Tb 3+, Sm 3+ phosphor with tunable color tone via energy transfer for white LEDs

Abstract

© 2015 The Royal Society of Chemistry. A series of Tb 3+, Sm 3+ co-doped CaLa 2 (MoO 4) 4 phosphors have been prepared via a solvothermal method without further sintering. The CaLa 2 (MoO 4) 4 :1% Tb 3+, x% Sm 3+ (x = 0.0-5.0) phosphors were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectra. Upon 277 nm excitation, the phosphors exhibit strong green emission of the Tb 3+ ions and red-orange emission of the Sm 3+ ions, the quenching concentration of Sm 3+ is determined to be about 4%. The critical distance between Tb 3+ and Sm 3+ has been calculated to be about 14.3 Å and the energy transfer from Tb 3+ to Sm 3+ occurs through a dipole-dipole interaction. The color tone of the obtained phosphors is easily modulated from blue to cool-white, green, and ultimately to warm-white-light. Furthermore, the relationship between the value of CCT for warm-white-light and the rare earth ion (Tb 3+, Sm 3+) concentration was investigated in detail. These results reveal that this kind of phosphor is a potential candidate for white LEDs.