The energy band structure, density of states and electronic density difference of Ca0.97Sr1.97AlO4F were calculated using the planewave pseudopotential method based on density function theory and generalized gradient approximation. The covalence of Ca0.97Sr1.97AlO4F was studied with valence bond theory. The excitation and emission spectra and fluorescent lifetimes of Ca0.97Sr1.97AlO4F doped with Ce3+ were investigated. The results show that the valence band is mostly composed of O and F 2p orbital, while the conduction band is mainly constructed from the Sr(1), Sr(2) atoms 4d and Al atoms 2p orbits, the energy gap is 6.235 eV. The bond covalence of Ca/Sr(2)-O and Ca/Sr(2)-F is strengthened with increasing the concentration of Ca2+in Sr 3 AlO 4 F host. The emission peaks and fluorescence lifetime (τ1/e) of Ce3+ in both two sites of 10-fold oxy-fluoride coordination (Sr(1)O8F2) and 8-fold coordination (SrO6F2) are about 472 nm, 38.35 ns and 550 nm, 49.45 ns, respectively.%利用基于密度泛函理论框架下的平面波赝势法和广义梯度近似，计算分析Ca0.97Sr1.97AlO4F晶体结构的能带结构、态密度及电子密度差；采用价键理论研究Ca 0.97 Sr 1.97 AlO 4 F的共价性，并探讨Ce3+在Ca 0.97 Sr 1.97 AlO 4 F体系中的激发、发射光谱及荧光寿命。结果表明，价带主要由O、F原子的2p轨道构成，导带则主要由Al原子的2p轨道和Sr(1)和Sr(2)原子的4d轨道构成，能带间隙为6.235 eV；在Sr3AlO4F掺入Ca2+离子后，Ca/Sr(2)-O 和Ca/Sr(2)-F共价性明显增强；Ce3+离子在十配位的Sr(1)O 8 F 2和八配位的Sr(2)O 6 F 2格位中的发射主峰分别约为472和550 nm，荧光寿命(τ1/e )分别为38.35和49.45 ns。
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