URL https://www.researchgate.net/publication/337455760/figure/fig2/AS:941651950333967@1601518728481/SEM-images-of-the-Sr091Er001Yb005F2-particles-along-with-12-a-13-b-14-c.jpg
URL2 https://www.researchgate.net/figure/SEM-images-of-the-Sr091Er001Yb005F2-particles-along-with-12-a-13-b-14-c_fig2_337455760
