TRACK FORMATION AND DISLOCATION LOOP INTERACTION IN SPINEL IRRADIATEDWITH SWIFT HEAVY-IONS

The microstructure of polycrystalline stoichiometric magnesium alumina te spinel (MgAl2O4) has been examined by cross-section electron micros copy following 430 MeV Kr+ or 614 MeV Xe+ ion irradiation near room te mperature up to a fluence of 1.1 x 10(16) ions/m(2). In addition, the microstructure was examined for two spinel specimens which had been pr eirradiated with either 2 MeV Al+ ions or 3.6 MeV Fe+ ions and subsequ ently irradiated with 430 MeV Kr+ ions. The Al+ and Fe+ preirradiated specimens contained a high density (10(21)-10(23) m(-3)) of interstiti al dislocation loops with diameters between 5 and 30 nm prior to the s wift heavy ion irradiation. Near-continuous latent ion tracks were obs erved in all of the specimens irradiated with swift heavy ions. The sw ift heavy ions also appeared to efficiently destroy pre-existing dislo cation loops with diameters <5 nm, whereas larger loops remained intac t following the swift heavy ion irradiation. The swift heavy ions caus ed structural disordering of the octahedral cautions, but did not appe ar to produce amorphous cores in the ion tracks, The disordered ion tr ack diameters were similar to 2.0 and similar to 2.6 nm for the 430 Me V Kr and 614 MeV Xe ion irradiations, respectively. (C) 1998 Published by Elsevier Science B.V. All rights reserved.