Characterization of single-crystal and plasma-sprayed spinels before and after Ar+-ion irradiation was performed by XPS and RBS techniques. Two Olsand Mg2ppeaks were observed in both spinels, respectively, and the second peaks were observed at the positions of higher energies than those in unirradiated spinel. In the Ar+-ion irradiated plasma-sprayed spinel, Olspeak with higher energy was observed predominantly. Two Al2ppeaks were observed in Ar+-ion irradiated single-crystal spinel whereas only one Al2ppeak was observed in Ar+-ion irradiated plasma-sprayed spinel. It is indicated from these results that plasma-sprayed spinel is easily amorphized by Ar+-ion irradiation, compared with single-crystal spinel.