Effects of Composition Variations on the Crystalline Phases and Photoluminescence Properties of Ca(2+x)MgSi(2)Eu(0.025)O(7+x) Phosphors

[Image: see text] A solid-state reaction method was used to synthesize Ca(2+x)MgSi(2)Eu(0.025)O(7+x) (x = 0–1.0) powders in the air atmosphere and in a reduction atmosphere (95% N(2) + 5% H(2)) at 1350 °C and 4 h, and the reduction atmosphere was removed at 800 °C. Only the Ca(2)MgSi(2)O(7) phase was found in the XRD pattern of the synthesized Ca(2)MgSi(2)Eu(0.025)O(7) powder. The first important discovery was that when the x value of Ca(2+x)MgSi(2)Eu(0.025)O(7+x) powders was increased from 0.2 to 0.8, both Ca(2)MgSi(2)O(7) and Ca(3)MgSi(2)O(8) phases coexisted in the synthesized Ca(2+x)MgSi(2)Eu(0.025)O(7+x) powders, and the diffraction intensity of the Ca(2)MgSi(2)O(7) (Ca(3)MgSi(2)O(8)) phase decreased (increased) with the x value. The second important discovery was that the Ca(2)MgSi(2)Eu(0.025)O(7) phosphor exhibited stronger photoluminescence excitation (PLE), photoluminescence (PL), and decay curve properties than the Ca(2.2)MgSi(2)Eu(0.025)O(7.2) phosphor, and the Ca(3)MgSi(2)Eu(0.025)O(8) phosphor exhibited stronger PLE, PL, and decay curve properties than the Ca(2+x)MgSi(2)Eu(0.025)O(7+x) phosphors for x = 0.4, 0.6, and 0.8. For x = 0.2–0.8, the PL spectra of the Ca(2+x)MgSi(2)Eu(0.025)O(7+x) phosphors were a combination of the PL spectra of Ca(2)MgSi(2)Eu(0.025)O(7) and Ca(3)MgSi(2)Eu(0.025)O(8) phosphors. The third important discovery was that as the x value was increased, the maximum emission peak wavelengths of the Ca(2+x)MgSi(2)Eu(0.025)O(7+x) phosphors shifted to a lower value, the maximum emission intensity of the PL spectra increased, and the emission light changed from green and cyan to blue.