Study on Hollow Hydroxyapaptite Microspheres Prepared by a Borate Glass Conversion Process

Hollow hydroxappatite(HAP) microspheres consisting of a hollow core and a porous shell were prepared by a Li-Ca-B glass conversion process.The phase composition,morphology and pore structure on the shell wall were investigated using XRD,SEM and BET.The results showed that the as-prepared microspheres possessed good internal hollow structure.The shell wall of the microsphere was made up of HAP crystals fully.After heat-treated at 600℃ for 2h,the compressive strength of the microsphere was determined to be(2.1±0.6)MPa,and the porosity and pore size of the shell wall were 85% and 60nm,respectively.Furthermore,the formation mechanism of the hollow HAP microsphere was also suggested.In phosphate solution,Ca-P-OH hydrate was in-situ formed on the surface of the glass and precipitated in the position initially occupied by Ca2+,while the pores were formed in the position initially occupied by Li+ and B3+.These hollow HAP microspheres may be useful for drug delivery.