Fig. 1. Characterization of BGO∶Cr_0.06, Sm_x. (a) XRD patterns of BGO∶Cr_0.06, Sm_x (x=0, 0.002, 0.004, 0.006, 0.008, 0.010) PersL materials; (b) refinement XRD patterns of BGO∶Cr_0.06, Sm_0.004 PersL materials; (c) crystal structure of BGO∶Cr_0.06, Sm_0.004 PersL material; (d) SEM picture of BGO∶Cr_0.06, Sm_0.004 PersL material; (e) EDS spectrum of BGO∶Cr_0.06, Sm_0.004 PersL material; (f) element distribution mapping of BGO∶Cr_0.06, Sm_0.004 PersL material

Fig. 2. Optical properties of BGO∶Cr0.06,Smx. (a) Gaussian fitting curves of emission spectra of BGO∶Cr_0.06, Sm_x (x=0, 0.002, 0.004, 0.006, 0.008, 0.010) PersL materials; (b) afterglow decay curves of BGO∶Cr_0.06, Sm_x (x=0, 0.004) PersL materials; (c) afterglow decay fitting curve of BGO∶Cr_0.06, Sm_0.004 PersL material; (d) thermoluminescence of BGO∶Cr_0.06, Sm_0.004 PersL material; (e) two-dimensional thermoluminescence curve of BGO∶Cr_0.06, Sm_0.004 PersL material; (f) NIR persistent luminescence mechanism of BGO∶Cr, Sm PersL materials

Fig. 3. CIE color coordinates of PersL materials. (a) BGO∶Cr_0.06; (b) BGO∶Cr_0.06,Sm_0.004

Fig. 4. Thermal stability of BGO∶Cr_0.06, Sm_0.004 PersL material. (a) Emission spectra from 30 to 300 ℃; (b) contour graph of thermal quenching behavior; (c) temperature-dependent integrated intensity and full width at half-maximum (FWHM)

Fig. 5. XRD patterns and emission spectra of BGO∶Cr_0.06, Sm_0.004 PersL material prepared at different calcination temperatures. (a) XRD patterns; (b) emission spectra

Table 1. Fitting parameters of afterglow decay curve of BGO∶Cr_0.06, Sm_0.004 PersL material