Author/Authors :
Chen، نويسنده , , Lei and Xue، نويسنده , , Shaochan and Chen، نويسنده , , Xiuling and Bahader، نويسنده , , Ali and Deng، نويسنده , , Xiaorong and Zhao، نويسنده , , Erlong and Jiang، نويسنده , , Yang and Chen، نويسنده , , Shifu and Chan، نويسنده , , Ting-Shan and Zhao، نويسنده , , Zhi and Zhang، نويسنده , , Wenhua، نويسنده ,
Abstract :
The synthesis and component of red phosphor, Sr4Al14O25: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr4Al14O25 were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr2+ and Al3+ in Sr4Al14O25. As a result, the strong covalence of Al3+ in the AlO4 tetrahedron other than in the AlO6 octahedron is disclosed. The deep red emission is attributed to Mn4+ occupying the center of AlO6 octahedron. The mechanism of energy transfer is mainly through dipole–dipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.
Keywords :
optical materials , Luminescence , X-ray absorption near-edge structure (XANES) , Phosphors , electron spin resonance
