A Facile Method Using a Flux to Improve Quantum Efficiency of Submicron Particle Sized Phosphors for Solid-State Lighting Applications

Abstract

This work successfully verified that the addition of a flux (NH4F, NH4Cl, and H3BO3) during synthesis has an impact on the crystallite size and quantum efficiency of submicron-sized particles of CaMgSi2O6:Eu2+ phosphors. The addition of NH4F or NH4Cl increased the crystallite size in the submicron-sized particles, yielding an increase in emission intensity and quantum efficiency. On the other hand, the use of the H3BO3 flux crystallized a secondary phase, SiO2, and changed the lattice parameters, which degraded the luminescent properties. In addition, an excessive amount of NH4Cl was examined, resulting in nucleation of a secondary phase, CaSiO3, which changed the lattice parameters with no improvement in luminescent properties. These results demonstrate that the addition of a flux could be a method to improve the quantum efficiency of submicron-sized particles composed of nanocrystallites; however, a judicious choice of the flux composition and amount has to be carefully considered.