Morphology control of $(Y_xGd_{1-x})_2O_3$:Eu (0≤x≤1) phosphor particles was attempted by spray pyrolysis using the stable colloidal solution prepared by liquid phase reaction method as spray solution. The
$(Y_xGd_{1-x})_2O_3$:Eu particles prepared from colloidal solutions containing small amount of gadolinium(or yttrium) hydroxy carbonate sol as seed material had spherical and filled morphology before and after post-treatment. On the other hand, the particles prepared from aqueous solutions were porous and hollow and the structure was broken after post-treatment. The size of colloidal particles affected the morphology of phosphor particles. The particles prepared from colloidal seed solution with 250 nm sol had spherical and filled morphology with clean surface while the particles prepared from colloidal seed solution with 70 nm sol had collapsed spherical shape. The $(Y_xGd_{1-x})_2O_3$:Eu phosphor particles prepared from colloidal solution had higher crystallinity and photoluminescence characteristics. In the case of $Y_2O_3$:Eu phosphor, PL(photoluminescence) intensity increased up to 16 %.
