Diametral strength testing of hydroxyapatites doped with yttrium and fluoride

This study aimed to investigate the diametral strength testing of hydroxyapatite (HA) doped with Y and fluoride with different compositions. Hydroxyapatites were synthesised by precipitation method and sintered at 900, 1100 and 1300 degrees C for 1 h. High amounts of doping caused a decrease in relative densities of HAs. Higher sintering temperatures helped in increasing the relative densities. No second phases were observed by X-ray diffraction spectra of 2.5 mol.-%Y and 2.5 mol.-%F doped HA after the sintering at all temperatures. Trace amounts of beta-tricalcium phosphate was found in 7.5 mol.-%Y and 2.5 mol.-%F doped HA sintered at 1100 and 1300 degrees C. Diametral strength of doped HAs mostly enhanced with the addition of Y3+ and F- . 2.5YFHA sintered at 1300 degrees C had the highest diametral strength of 11.6 MPa with a relative density of 94.3% of theoretical density.