Effects of Fluxes on Particle Morphology and Phase Formation of (Sr,Ba)Si_2O_2N_2:Eu~(2+) Phosphors

摘要

An yellow-emitting phosphor for white LED application, (Sr,Ba)Si_2O_2N_2:Eu~(2+), has tabular particle shapes with very broad size distribution, when prepared by a reported method utilizing NH4CI as a flux. To improve this disadvantage, effects of other fluxes were investigated. Addition of 2 wt.% or less alkali or ammonium nitrate provides more bulky particles of narrower size distribution with little sacrifice of efficiency. Meanwhile, nitrates at high amount of addition and borates as well produce a secondary phase, (Sr,Ba)_3Si_6O_9N_4:Eu~(2+), having poor efficiency, though bulky shapes are obtained This is probably because some of corner-shared [SiN_4]~(8-) tetrahedra are replaced by tetrahedra bridged by O atoms.