Generally, the emission intensity of phosphors can be enhanced by introducing a proper number of defects. To enhance the emission intensity of Ca-4.85(BO3)(3)F(C4.85BF):0.15Bi(3+), more Frenkel defects were introduced by Na+, Sr2+, and Ba2+. It is found that the number of Frenkel defects is related to volume and covalence of the crystal, in which the covalence has a greater effect than the volume. Furthermore, the larger the volume of the crystal is, the stronger the covalence of the crystal is, the more Frenkel defects will be produced. The volume of Ca4.85-xSrx(BO3)(3)F(C4.85-xSrx BF):0.15Bi(3+) is larger than that of Ca4.85-xNax(BO3)(3)F(C4.85-xNax BF):0.15Bi(3+); however, the covalence of Na+ is similar to that of Sr2+, which leads to the same trap depth (E-alpha) and defect density (mu(g)) in the quenching concentration. The results also confirmed that the number of Frenkel defects is mainly influenced by the covalence of crystal. Furthermore, crystal distortion also affects the number of Frenkel defects. C4.85-xSrxBF:0.15Bi(3+) and C4.85-xNaxBF:0.15Bi(3+) have the same distortion at quenching concentration, which results in the same emission intensity in the quenching concentration. Ca4.85-xBax(Bo(3))(3)F (C4.85-xBaxBF):0.15Bi(3+) has a larger volume and stronger covalence; meanwhile, it has deeper trap depth (E-alpha) and larger defect density mu(g)) at the quenching concentration, comparing with C4.85-xSrxBF:0.15Bi(3+) and C4.85-xNaxBF:0.15Bi(3+). However, the distortion of C4.85-xBaxBF:0.1.5Bi(3+) is in agreement with C4.85-xNaxBF:0.15Bi(3+) and C4.85-xSrxBF:0.15Bi(3+), which leads to the emission intensity of C4.85-xBaxBF:0.1.5Bi(3+) basically the same as that of C4.85-xNaxBF:0.15Bi(3+) and C4.85-xSrxBF:0.15Bi(3+) in quenching concentration. And the different rates of distortion result in the different quenching concentrations of C4.85-xNaxBF:0.15Bi(3+), C4.85-xSrxBF:0.15Bi(3+), and C4.85-xBaxBF: 0.15Bi(3+). Moreover, for Ca4.85-xMgx(BO3)(3)F(C4.85-rMgxBF):0.15Bi(3+) and Ca-4.85(BO3)(3)F1-yCly(C4.85BF1-yCly):0.15Bi(3+), there are no Frenkel defects due to weaker covalence and smaller volume of the crystal in C4.85-xMgxBF:0.15Bi(3+). However, Frenkel defects can be observed in C4.85BF1-yCly:0.15Bi(3+) due to stronger covalence and larger volume of the crystal, furthermore, and the emission spectra and thermoluminescence spectra of C4.85BF1-yCly:0.15Bi(3+) are similar to those of 0.15Bi(3+) doped C4.85-xNaxBF:0.15Bi(3+), C4. 85-xSr(x)BF:0.15Bi(3+), and C4.85-xBaxBF:0.15Bi(3+).