## 3 Results and Discussion  
### Characterization and Optical Properties of S-Phosphor  
As can be seen from Figure 1a, the monoclinic diffraction peaks of the reacted phosphor dominate in the XRD spectra, which were similar to those of the SAOED before the reaction. It indicates that the crystal structure of the phosphor was not destroyed after treatment. As shown in Figure 1b, the broad XPS spectra of the solvent-heat-treated phosphor in the range of 0-1200 eV showed the presence of Sr (3s, 3p, 3d), Al (2s, 2p), O1s, and C1s peaks in the spectra, which indicated that the product consisted of strontium, aluminum, and oxygen elements. The results of the XPS analyses indicated that the compositions of the reacted phosphors were essentially the same as those of the untreated bulk phosphor. EDX spectroscopy (Figure 1c) further confirmed the chemical composition of the products. The mass and atomic ratios of the elements of the untreated bulk phosphor and the reacted phosphor conform to the stoichiometric formula of SrAl2O4. Figure 1f shows HRTEM images taken on the reacted phosphor. The spacing between neighboring lattice planes was 0.201 nm, which corresponds to the (\(-\)2 2 2) crystal planes of Joint Committee on Powder Diffraction Standards (JCPDS) standard card No. 34-0379. As can be seen in Figure 1e,f, as well as Figure 2, the overall particle size of the phosphor was reduced from 42.3 \(\upmu\)m to 23.6 \(\upmu\)m after solvent heat treatment, and the change in particle size was obvious. Although the average size cannot be directly reduced to nanometer size or submicron size, the phosphor size in the submicron size range before and after the reaction was increased from 0.56% to 3.158% by volume. Compared with the untreated phosphor, most of the surface corners of the reacted phosphor became less obvious. Figure 1: (**a**) X-ray diffraction (XRD) patterns of original phosphors and S-phosphor. (**b**) X-ray photoelectron spectroscopy (XPS) pattern of S-phosphor. (**c**) Energy dispersive analysis (EDS) pattern of S-phosphor. (**d**) Selective area electron diffraction (SAED) pattern of S-phosphor. (**e**) Scanning electron microscopy (SEM) image of original phosphors. (**f**) SEM image of S-phosphor. As can be seen in Figure 3, the excitation and emission spectra of the phosphor remain relatively stable in their positions before and after the reaction. The excitation spectrum consists mainly of excitation bands in the wavelength range of 300-450 nm, with a distinct peak at 360 nm and a shoulder peak at 420 nm. This indicates that the sample has a good excitation response to both UV and visible light. On the other hand, the emission spectrum shows a symmetrical and continuous broadband spectral pattern with the emission peak clearly located at 512 nm, and the emission intensity of S-phosphor remains at 91.39% of the original sample. This peak was mainly attributed to the radiative excitation process between the 46\({}^{\circ}\) 5d\({}^{1}\) excited state and the 47\({}^{\prime}\) ground state of the Eu\({}^{2+}\) ion [39]. In addition, the afterglow decay curves before and after the reaction show a similar trend, and the afterglow lifetime of S-phosphor was 94.98% of the original sample. This indicates that the luminescence center of the phosphor and its crystal structure were not significantly damaged after the dynamic solvent heat treatment. In this work, we found that during the reaction process, cracks appeared in the phosphor blocks and \"tore\" at the cracks, thus splitting the large-particle block phosphor into multiple small-particle block phosphors. In the reaction kettle, we added a magnetic stirrer and stirred while reacting. The block phosphor was constantly subjected to pressure and solvent washing inside the kettle, and the block produced cracks during the reaction process. The surface of the untreated strontium aluminate luminescent material was relatively smooth, and no cracks appeared (Figure 4a).