FAST NEUTRON-IRRADIATED MAGNETITE AND HEMATITE INVESTIGATED BY NEUTRON-DIFFRACTION

In this paper, we present new experimental results about crystallograp hic and magnetic properties obtained on magnetite Fe3O4 and haematite alpha-Fe2O3 samples irradiated by fast neutrons. Polycrystalline rods were irradiated at 350K by fast neutrons inside the core of Melusine n uclear reactor (CENG) in Grenoble at various fluences (4 10(19), 9.2 1 0(19) and 20 10(19) neutrons/cm(2)). The irradiated samples have been studied by the neutron diffraction technique. Contrary to the case of garnets ferrites, where amorphization is observed at such fluences, no similar effect is observed in magnetite : one just observes a very we ak swelling. Results about haematite are also discussed.