Sol-Gel Combustion Synthesis of La-9.33(SiO4)(6)O-2 Oxyapatite

Abstract

Synthesis of La-9.33(SiO4)(6)O-2 was performed by a new method that represents the combination of sol-gel and combustion procedures using glycine as the fuel. Syntheses were performed from ethanol-water solutions of oxides precursors, lanthanum nitrate and tetraethyl orthosilicate. The optimum synthesis parameters have been established by varying molar ratio of tetraethyl orthosilicate to water as well as glycine to NO3- ions. The phase identification and the structural characterization were performed by X-ray powder diffraction. The pure nanocrystalline La-9.33(SiO4)(6)O-2 with the crystallite sizes of 32 nm was directly synthesized during combustion process of homogeneous gel that was generated in solution with the following molar ratios: glycine: NO3- = 0.56 and tetraethyl orthosilicate: water = 1:20. Well-crystallized La-9.33(SiO4)(6)O-2 structure was obtained after heating at 1200 degrees C. The lattice parameters a = 9.7156(9) and c = 7.1810(8) angstrom confirmed the composition La-9.33(SiO4)(6)O-2.