Рroperties of Bioactive Thin-Films Based on System SiO2-P2O5-CаO and SiO2-P2O5-СаO-Na2O Obtained by Sol-Gel Method

Thin films were synthesized from alcohol film-forming solutions based on tethraethoxysilane, phosphoric acid, calcium chloride and sodium chloride using sol-gel method. Thin films were produced on the single-crystal silicon substrates (model substrate) by extraction at a velocity of 5 mm/s following by heat treatment at a temperature of 60°С for 20 minutes and at a temperature of 600°С for 1 hour. During the experiment it was established that film-forming solutions are usable only for 2 to 7 days from the moment of preparation. Using thermal and infra-red – spectroscopic analysis main stages of oxide system formation were retraced. According to data from x-ray phase analysis phases CaClH2PO4∙H2O, Ca (H2PO4)2∙H2O, CaHPO4∙2H2O, Ca2SiO4∙H2O, Ca5(PO4)3Cl и CaSiO3,NaCl, CaCl2, H2PO4·H2O, Ca5(PO4)3Cl, SiO2 are being registered in the sample. Biological activity of the received material was evaluated in SBF environment. Presence of the sodium oxide in the system leads to the increase in the bioactivity of the material. Such material intensively exchanges with solution in calcium ions and phosphate-ions; silanol groups fix calcium ions, furthering the formation of the layer of amorphous calcium phosphates gradually crystallizing in hydroxyapatite, and other calcium phosphates.