Abstract: The invention relates to a method for producing activated, substantially monodisperse, phosphorescent particles and particles formed thereby. The method suspends substantially monodisperse, phosphor-precursor particles in a fluidizing gas and then introduces a reactive gas to contact the suspended phosphor-precursor particles. Heating the suspended phosphor-precursor particles to a reaction temperature then forms unactivated phosphorescent particles. In another embodiment, the phosphor-precursor particles may be heated to a reaction temperature where they decompose to form the unactivated phosphor particles. The unactivated phosphorescent particles suspended within the fluidizing gas are activated by heating the unactivated phosphorescent particles to an activation temperature forming activated, substantially monodisperse, phosphorescent particles.