A phospholuminescent composition is provided that includes a phosphor having a composition represented by SrxBa2-xSiO4:Eu, wherein 0≦x≦2. The phospholuminescent composition also includes a magnesium salt added to the phosphor. The composition has an excitation spectra such that the ratio of the intensity at a wavelength of 440 nm to the intensity at a wavelength of 360 nm is in the range of 0.82 to 0.85. Alternatively, the composition has an excitation spectra such that an intensity at a wavelength of 440 nm ranges from 1.2 to 1.3 times an intensity of said phosphor alone at a wavelength of 440 nm.