Luminescence characteristics of Eu-doped calcium magnesium chlorosilicate phosphor particles prepared by spray pyrolysis

Europium (Eu)-doped calcium magnesium chlorosilicate [Ca ₈Mg(SiO₄)₄Cl₂:Eu²⁺] phosphor particles were prepared by spray pyrolysis and their luminescence characteristics were optimized by changing the Ca precursor type, the Eu ²⁺ content, and the post-treatment temperature. It was found that the ratio of calcium nitrate to calcium chloride, which were used as the source of Ca and Cl, respectively, significantly affects the luminescence intensity and the particle morphology. Photoluminescence intensity was monotonically increased by increasing calcium chloride content with respect to calcium nitrate content in the spray solution due to increases in the crystallinity and phase purity of Ca₈Mg(SiO₄)₄Cl₂:Eu²⁺. Ca₈Mg(SiO₄)₄Cl₂:Eu²⁺ was gradually turned from a spherical shape to a polyhedral shape of micron size as the calcium chloride content was increased in the spray solution. The concentration quenching of Eu²⁺ was observed at 0.375 mol % Ca. The optimized Ca₈Mg(SiO₄)₄Cl₂: Eu ₂₊, which showed a broad emission spectrum from 460 to 550 nm with a peak position at 502 nm, had a high brightness under the excitation by short- and long-wavelength ultraviolet lights and is expected to be successfully applied as a green phosphor for UV light emitting diodes (LEDs).