Effect of particle size of starting oxide powders on the performance of doped-lanthanum oxyapatite produced by mechanical alloying followed by microwave sintering

摘要

La9.33Si2Ge4O26 oxyapatite powders were synthesized at room temperature through mechanical alloying of La2O3, GeO2 and SiO2 precursor powders with different particle sizes as well as crystal structure in the case of silica powder (crystalline/amorphous). The mechanical alloyed mixtures were subsequently sintered by microwave heating at 1350 C for 1 h in order to obtain dense and homogeneous materials. All sintered materials consisted of the target apatite phase although minor amounts of secondary phases (e.g.La4GeO8) were also present only in samples obtained from micrometric SiO2 powders with a crystalline structure. The microstructure of the materials obtained from nanometric SiO2 with an amorphous structure was found to be more homogenous than the ones obtained from micrometric/crystalline silica. The mechanical behavior of the samples was slightly dependent on the particle size of the precursors and on the SiO2 crystallinity.