Figure 4. 3D surface of SEM images of the selected area for elemental analysis of hydroxyapatite Figure 4. 3D surface of SEM images of the selected area for elemental analysis of hydroxyapatite (HAp) (HAp) ( a ) 7ZnHAp ( b ), and 20ZnHAp ( c ) samples. ZnHAp: zinc-doped hydroxyapatite. ( a ) 7ZnHAp ( b ), and 20ZnHAp ( c ) samples. ZnHAp: zinc-doped