Evolution of Luminescence of Sr_{2–<i>y</i>–<i>z</i>}Ca_<i>z</i>Si(O_1–<i>x</i>N_<i>x</i>)₄:<i>y</i>Eu²⁺ with N^3–, Eu²⁺, and Ca²⁺ Substitutions

Sr_{2–<i>y</i>–<i>z</i>}Ca_<i>z</i>Si­(O_1–<i>x</i>N_<i>x</i>)₄­:<i>y</i>Eu²⁺ (SCSON:Eu²⁺) solid solutions were prepared by substituting N^3‑, Eu²⁺, and Ca²⁺ ions into Sr₂SiO₄ (SSO). These ions contributed differently to the evolution of luminescence of SCSON:Eu²⁺. SSON:Eu²⁺ (<i>z</i> = 0) has two activation centers: Eu­(I) and Eu­(II). The nitridation effects led to a dramatic change in the crystal field surrounding the Eu­(II) site but rarely affected the Eu­(I) site. Accordingly, SSON:Eu²⁺ exhibited broad excitation spectra from ultraviolet to visible wavelengths. In comparison with the Eu­(II) green emissions of SSO:Eu²⁺, the dominant peak wavelengths (DPWs) of the Eu­(II) emissions were at red emission regions (605–630 nm), depending on the amount of Eu²⁺ ions. The Ca²⁺ ions of SCSON:Eu²⁺ preferentially changed the emission wavelength assigned to Eu­(I) and affected the Eu­(II) emission intensity. In addition to the spectral properties, the chromaticity coordinates and a low thermal quenching behavior of SCSON:Eu²⁺ powders demonstrated that they can be a novel red phosphors for use in white light emitting diodes