Nano hydroxyapatite (nHAP) is known to exhibit enhanced biological response when interacting with cells. Phase pure HAP nanoparticles were synthesized by self-propagating high temperature synthesis (SHS) using citric acid and urea as fuels and aqueous precipitation with calcium nitrate and ammonium hydrogen phosphate. The effects of the critical factors governing the synthesis protocols such as pH, reaction and calcination temperatures on the stoichiometry, crystallinity, crystal size, and shape of the nano HAP powders are reported. The results indicated that the crystal sizes, similar to natural bone and teeth, varied with some agglomeration in the nanoregime of 10-80 nm. The influence of grain size, sintering temperature and density of bodies using nHAP as precursor is discussed. Microstructure, crystal structure, morphology, surface area of nHAP powders and dense bodies were investigated using XRD, SEM, TEM, DTA-TG and BET analysis.
Key words: nano hydroxyapatite, SHS, precipitation, synthesis, characterisation, line broadening