Influence of Na₂O and TiO₂ Additives on Properties of Bioactive Thin Film Materials Based SiO₂–P₂O₅–СаO System

The purpose of this study was to use the sol-gel method in synthesis of thin films of alcohol film-forming solutions based on tetraethoxysilane, phosphoric acid, calcium chloride, sodium chloride, tetrabutoxytitanium. We obtained thin films on single-crystal silicon substrates (model substrate) by centrifugation followed by heat treatment at 60 °C for 20 minutes and at 600, 800 °C for 1 hour. Findings of the research show that solutions for preparing the films could be used from 2 to 7 days from the date of preparation. According to the X-ray phase analysis in the sample at a temperature of 600 °С and above crystalline forms of SiO₂, CaSiO₃, Ca₂P₂O₇, complex phosphates, anatase are fixed. Furthermore, we studied the acid-base properties of the surface of film-forming solutions dried at a temperature of 60 °C and annealed at 600 and 800 °C. Regardless of the composition of the initial system, the Brensted acid sites predominate on the surface of the samples dried at 60 °C; for samples annealed at 600 and 800 °C, the pH value increases sharply and the finely divided sample is the Brensted base. We evaluated the average pore size for the samples. For the SiO₂--P₂O₅--CaO system, samples dried at 60 °C have an average pore size of 5 nm, with the addition of sodium oxide to the system, the average pore size decreases to 2.41 nm, when the titanium oxide is added to the system, the average pore size increases to 7.6 nm. For the samples annealed at 600 °C, the average pore size is 20; 6.9; 26.3 nm respectively. At a temperature of 800 °C, the average pore size is 26.2; 8.1; 34.4 nm respectively. The biological activity of the resulting materials was evaluated in SBF medium. When introduced into the titanium oxide system, the material shows high bioactivity

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