In allusion to the problems existing in the defect-related luminescent materials, a series self-activated light emitting semiconductors of Li 3 AlN 2 : R (R=0, Na + , Mg 2+ , Si 4+ , Tb 3+ , Eu 3+ ) have been successfully synthesized by sample-pressure sintering. Under the excitation at 422 nm, a yellow light peaked at 580 nm have been observed in the host lattice of Li 3 AlN 2 . The crystal structure and the electron structure of Li 3 AlN 2 have been measured to investigate the defect-related luminescent properties of Li 3 AlN 2 using the Rietveld refinement on the basic of X-ray diffraction data and the density functional theory (DET). The results show that Li 3 AlN 2 crystallizes in cubic phase with full filled edge-shared (Al/Li)N 4 tetrahedrons and is a wide-bandgap semiconductor. The impurity defects produced by ions substitution have also been investigated, which leads to the red-shift of the emission peak. Finally, the photoluminescence excitation (PLE) spectrum of Li 3 AlN 2 with two excitation bands peaked at 300 nm and 422 nm has been detected, and the latter matches well with near-UV LED chips. The thermal stability shows that integral intensity of Li 3 AlN 2 at 150°C still has 60% of the initial intensity at room temperature. The results indicate their potential applications as the LED used phosphors. K E Y W O R D S nitrides, phosphors, semiconductors