Abstract
Hollow magnetite (Fe3O4) microspheres a few tens micrometers in diameter were fabricated by calcining iron hydroxide precipitated on spherical polydivinylbenzene (PDVB) template with enzymatically supplied ammonia. Monophasic Fe3O4 hollow spheres were obtained by calcining the precursor at 1073 K for 3.6 ks in an equimolar mixed gas of CO2 and H2. The prepared Fe3O4 hollow spheres had smooth surfaces. The particle size and monodispersity of Fe3O4 spheres reflected those of the PDVB template, and the latter was controllable 10-30 μm in diameter during the process of the polymerization. The Fe3O4 spheres showed ferrimagnetic behavior. The use of urease to precipitate the precursor was found to be effective for preparing template-directed microspheres, and the Fe3O4 microspheres synthesized are considered to be promising thermoseeds for hyperthermic treatment.
