Phase Composition of Hydroxyapatite Synthesis Products from a Model Solution of Synovia in the Presence of Magnesium and Zinc Ions

The paper considers the possibility of cationic isomorphic substitutions for controlling and changing the properties of hydroxyapatite (HA). HA was synthesized by changing the concentration of Mg2+, Ca2+ ions and adding Zn2+ ions at physiological pH 7.45 ± 0.05 from a model solution of synovia. It was found that the synthesis carried out with an increase in the concentration of magnesium ions leads to the appearance of a new phase—whitlockite. A large volume of the unit cell and a variety of different structural positions determine the ability of whitlockite to a variety of isomorphism. This largely serves as a source of a wide range of functional properties inherent in compounds with this structural type. Synthesis carried out with a simultaneous increase in the concentration of Mg2 ions and a decrease in the concentration of Ca2+ ions has a huge destabilizing effect on the formation of HA and leads to the formation of new phases: whitlockite, phosphate, oxide and hydroxide of magnesium. It has been established that synthesis with the introduction of small amounts of Zn2+ ions (up to 12 mg/L inclusive) does not affect the phase composition of the obtained samples, the amorphousness of the solid phase and the mass of the resulting sediments increase slightly, and the size of the crystallites decreases. Synthesis of new compounds with specified physical properties and chemical composition is a relevant and practical task.