“…This is because not only are impurities ubiquitous through the lifetime of PuO 2 such as in its production, purification, fabrication, storage, application, and recovery but also the inherent radioactivity (decay and fission) of Pu results in the continuous accumulation of a large variety of transmuted products . On the whole, impurities in PuO 2 exhibit negative effects; particularly, the incompatible rare gases (RGs) have been confirmed to deteriorate the macroscopic properties of PuO 2 or other Pu-based materials despite the fact that the underlying microscopic mechanisms remain unclear. − However, a few impurities are found to be beneficial; for instances, Zr can stabilize oxide-type nuclear fuels under radiation conditions and enhance their thermal conductivity, and carbon can retard or restrain Pu corrosion. − Naturally, the positive effects provide guidance for tailoring the functionalities of PuO 2 , similar to the cases of its analogues such as UO 2 and CeO 2 ; in fact, U-Zr-O and Ce-Zr-O ternary compounds have been technologically and industrially used, and more ternary compounds are under validation for potential applications. − Unfortunately, to our knowledge, there is still an extraordinary scarcity of relevant comprehensive studies in the literature regarding impurities in PuO 2 . In experiments, on one hand the scarcity is attributed to the difficulties in handling and preparing high-quality radioactive PuO 2 samples; on the other hand, a detailed microscopic characterization of solid-state materials doped by low-concentration impurities is quite a challenging task.…”