A series of sintered UO₂ pellets doped with lanthanide (Ce, Nd, Yb) elements were investigated using powder X-ray diffraction, Raman spectroscopy, thermogravimetric analyses and differential scanning calorimetry. A combination of electron microprobe and thermogravimetric analyses, for oxygen content, enabled precise determination of the hypostoichiometry for lanthanide-doped samples at 1 and 5 atom percent. Two Raman laser wavelengths (785 and 455 nm) have afforded greater sensitivity to spectroscopic signatures of the phonon bands (1LO and 2LO) associated with oxidation of (U_1-yM_y)O_2-x and the anion defects introduced by lanthanide substitution. Oxygen hypostoichiometry forces a reduction in the average coordination number surrounding (U,M) sites, which is compensated by a decrease in U–O bond length, and concomitantly the lattice parameter, consistent with the obtained Raman spectra. The evolution of O/M ratio up to (U_1-yM_y)O₂ after oxidation was also examined using Raman spectroscopy, revealing that the ‘defect band’, including a component attributed to oxygen vacancies (∼540 cm⁻¹) and the 1LO phonon (∼575 cm⁻¹) increased in intensity with increasing dopant concentration and upon oxidation. The lanthanide dopants inhibited oxidation to U₃O₈, most prominently for Yb 5 at%, having been delayed by ∼180 °C. Thermogravimetric analyses reveal an early oxidation feature that may be related to influx of O to satisfy hypostoichiometry up to (U_1-yM_y)O₂, possibly stabilizing a U₄O₉ or U₃O₇ intermediate, delaying oxidation to U₃O₈.

使用粉末X射线衍射，拉曼光谱，热重分析和差示扫描量热法研究了掺杂镧系元素（Ce，Nd，Yb）的一系列烧结UO ₂球团。通过电子探针和热重分析的结合，可以测定氧含量为1和5原子百分比的镧系元素掺杂样品的化学计量比。两个拉曼激光波长（785和455 nm）对与（U _1-y M _y）O _2-x氧化有关的声子带（1LO和2LO）的光谱特征提供了更高的灵敏度以及由镧系元素取代引起的阴离子缺陷。氧化学计量法迫使（U，M）位点周围的平均配位数减少，这由U–O键长的减少以及相应的晶格参数的减少所补偿，与获得的拉曼光谱一致。还使用拉曼光谱法检查了氧化后O / M比例直至（U _1-y M _y）O ₂的演变，发现“缺陷带”包括归因于氧空位（〜540 cm ^-1）的成分。1LO声子（〜575 cm ^-1）的强度随掺杂剂浓度的增加和氧化而增加。镧系元素掺杂剂可抑制氧化成U ₃ O ₈，最显着的是Yb 5 at％，已延迟了〜180°C。热重分析揭示了一种早期氧化特征，该特征可能与O的流入有关，以满足高达（U _1-y M _y）O _2的化学计量，可能稳定了U ₄ O ₉或U ₃ O ₇中间体，从而延迟了氧化至U _{3的过程。} O ₈。