. the stoichiometric hydroxyapatite) . Potassium hydroxide S Ca NO 3 () 2 4H 2 O⋅ S Ca CH 3 COO() 2 H 2 O⋅ Klog O 3 – The Influence of N , CH 3 COO – , and Cl – Ions on the Morphology of Calcium. (up to 4 wt %) [3] . The presence of the absorption bands of nitrate and acetate groups can be explained by adsorption of the corresponding ions on the surface of HA crystals. Fur- ther annealing. the modifying effect of anions on the mor- phology of HA crystals could be caused by specific interactions of the anions with growing crystals: (i) adsorption of the anion on the apatite surface