• Gallet, Sophie Le
• Salem, Ezzedine Ben
• Hajji, Hanen
• Millot, Nadine
• Saviot, Lucien

Abstract

The presence of fluoride, lithium and carbonate group within hydroxyapatite occurring naturally within the body provides the basis for investigating the sintering ability of co-substituted hydroxyfluorapatites nanopowders for use as biomaterials. Ca10-xLix(PO4)6-x(CO3)x(OH)F nanopowders, with x equal to 0, 0.5, 1, 1.5, 2 and 2.5 were prepared using mechanosynthesis and their extensive characterization was realized. Substitution causes contraction of the unit hexagonal cell along the a-axis and elongation along the c-axis, as well as a decrease in the degree of crystallinity of the powders, and an increase of the amounts of unreacted calcium and lithium carbonates. Crystallite sizes and strains, determined by the Halder & Wagner method, remain the same whatever x. Spectroscopic analyses show that B-type carbonated apatite is formed. Annealing at 500°C improves the crystallinity of the apatite phase with low percentages of calcite and lithium phosphate as secondary phases (x<=2). Transmission electron microscopy observations show that untreated and calcined powders consist mainly of spherical nanoparticles. As-mechanosynthesized Ca9Li(PO4)5(CO3)(OH)F powder, sintered by Spark Plasma 2 Sintering, densifies in the temperature range of 580 to 650 °C. The crystallite size remains the same than that of the untreated-powder (about 15 nm).

Topics

• nanoparticle
• impedance spectroscopy
• phase
• transmission electron microscopy
• Lithium
• annealing
• Calcium
• biomaterials
• crystallinity
• sintering