ThO₂ is a promising matrix either for incineration or direct disposal of plutonium and (Th, Pu)O₂ is a potential advanced fuel. In this view, a ThO₂–CeO₂ mixed oxide system has been investigated under oxidizing as well as reducing conditions wherein CeO₂ has been employed as a non-radioactive surrogate for PuO₂. Selected compositions in Th_1−xCe_xO₂ (0 ≤ x ≤ 0.5) series were prepared by gelcombustion synthesis and thoroughly characterized by XRD and Raman spectroscopy. Both the studies confirm the formation of a fluorite-type (F-type) solid solution throughout the series after calcination of gelcombusted powders at 873 K in air. The F-type phase is retained even on annealing these solid solutions at an elevated temperature 1773 K in air. Lattice parameter of the F-type phase decreases as a function of ceria content in accordance with the Vegard’s law. On the contrary, the position of the F_2g Raman band in these solid solutions exhibits non-ideal behavior. Annealing of calcined samples at 1873 K in a reducing atmosphere (Ar−8% H₂) yields a single phase of F-type structure at x ≤ 0.2, while a biphasic phase field at x ≥ 0.3. Characteristic Raman vibration bands have been utilized to identify the presence of possible defects (due to Ce⁴⁺/Ce³⁺ substitution in ThO₂) that are otherwise difficult to detect by the XRD studies. Detailed structure and defect analysis in ThO₂–CeO₂ mixed oxides will not only give valuable insight to the fuel designer but also bring out fundamental chemical aspects of such mixed oxides.

ThO ₂是用于焚烧或直接处置p的有前途的基质，而（Th，Pu）O ₂是潜在的先进燃料。根据这种观点，已经在氧化和还原条件下研究了ThO ₂ -CeO ₂混合氧化物体系，其中CeO ₂被用作PuO ₂的非放射性替代物。Th _1-x Ce _x O _2中的选定成分（0≤x≤0.5）系列通过凝胶燃烧合成制备，并通过XRD和拉曼光谱进行了全面表征。两项研究均证实了凝胶燃烧粉末在空气中于873 K煅烧后，整个系列中均形成了萤石型（F型）固溶体。即使在空气中将这些固溶体在1773 K的高温下退火时，F型相也会保留。根据Vegard定律，F型相的晶格参数随二氧化铈含量的变化而降低。相反，在这些固溶体中F _2g拉曼能带的位置表现出不理想的行为。在还原性气氛（Ar−8％H ₂）在x≤0.2时产生F型结构的单相，而在x≥0.3时产生双相场。拉曼振动带的特征已被用于识别可能存在的缺陷（由于ThO _2中的Ce ⁴⁺ / Ce ³⁺取代），而这些缺陷很难通过XRD研究进行检测。ThO ₂ -CeO ₂混合氧化物的详细结构和缺陷分析将不仅为燃料设计者提供宝贵的见解，而且还将揭示这种混合氧化物的基本化学方面。