The effect of the scattering from ZrO$_{2}$: Y$_{2}$O$_{3}$ nano particles on the emitting properties of white light emitting diodes (LEDs) consisting of red-green phosphors (CaAlSiN$_{3}$:Eu$^{2+}$ with Lu$_{3}$Al$_{5}$O$_{12}$:Ce$^{3+}$) and a blue LED chip was investigated in this study. The color coordinates of white LEDs increased with increasing concentration of nanoparticles, and their changes were more substantial at larger concentration. Especially, the relative intensity of the red component in the white spectrum became higher at larger concentrations, which was attributed to the multiple-scattering effect for blue photons and green photons. The luminous efficiency decreased with increasing concentration of nanoparticles due to multiple scattering, trapping and reabsorption of emitted light in the encapsulant of the white LED. This study showed that appropriate color properties can be achieved, even using a smaller amount of expensive red phosphors, by utilizing nanoparticles and suggests the possibility of realizing low-cost, high-CRI (color rendering index) lighting devices.

Keywords: Illumination, Phosphor, White LED, Nanoparticle