Photoluminescence Properties and Valence Stability of Eu in CaMgSiO[sub 4]

The photoluminescence (PL) properties of europium-doped phosphors were systematically studied. -doped exhibited an intense red emission from the to manifold transitions of , whereas the -doped phosphors showed an extremely weak emission peaking at 475 nm due to the to transition of . The PL studies indicated that a complete reduction in to is not possible in . The vacuum ultraviolet spectrum of the undoped showed that the host absorption energy was at ca. 150 nm. Based on the bandgap energy, the location of the energy levels of and the Fermi level relative to the band structure of was deduced to discuss the valence stability of Eu and the luminescence behavior of . In addition, the electronic structure of was investigated by using the density functional theory with the local-density approximation.