**5. Effects of Chemical Composition**

This review has so far focused on SHI irradiation effects in pure CeO<sup>2</sup> having ideal or near-ideal stoichiometry. However, the study of related materials that deviate from this ideal composition can also provide valuable insight into its radiation response. First, swift heavy ion irradiation has been shown to induce local nonstoichiometry in CeO2, such that later ion impacts will interact not with ideal CeO2, but rather with a nonstoichiometric phase. Second, since CeO<sup>2</sup> is used as a surrogate for nuclear fuel materials, doping with different atomic species (mimicking the accumulation of fission products) is an important aspect to consider in SHI irradiations. Finally, because the redox chemistry of Ce appears to play a key role in the radiation response of CeO2, a comparative study of structurallyrelated materials featuring cations with distinct redox behavior can help to isolate the effects of cation chemistry on the response of this material to SHI irradiation.
