Nitrogen-rich Eu2+-doped Ca-α-SiAlON phosphors(Cam/2-xSi12-m-nAlm+nOnN16-n:xEu)were synthesized by a freeze-drying assisted combustion synthesis(CS)route.Fast-synthesized products with high purity and uniform particle morphology were confirmed by X-ray dif-fraction(XRD)and scanning electron microscopy(SEM).The analysis of lattice parameters by comparison with empirical equations showed that the as-prepared phosphors had low oxygen content.A series of samples were prepared according to the stoichiometry of Cam/2-0.08Si12-mAlmN16:0.08Eu for further research.The influences of m value on the luminescence properties were investigated in detail.As m increased,a redshift phenomenon was observed in both the excitation and emission spectra.First-principle electronic structure calculations showed that the 3d energy level of Ca played an important role in the occurrence of the redshift phenomenon.