Lu2Ti2O7和Lu2TiO5陶瓷材料的Kr离子辐照损伤研究

钛酸盐因其优异的物理化学性能，可作为高放射性核废物（HLW）和锕系元素（钚）的重要候选固化材料之一。采用传统的陶瓷烧结工艺制备了多晶的Lu₂Ti₂O₇和Lu₂TiO₅陶瓷材料。在室温下，用800 keVKr2+对两种材料进行辐照，辐照后的样品采用GIXRD进行表征，观察到两种样品都经历了先肿胀、然后再发生非晶相变的过程。不同的是Lu₂Ti₂O₇的晶格肿胀程度大于Lu₂TiO₅。另外，Lu₂TiO₅样品的辐照到2×10₁₄ ions/cm₂时非晶含量达95.54%，而Lu₂Ti₂O₇样品在此剂量下非晶含量只有74.66%。通过第一性原理计算了Lu₂Ti₂O₇晶体的晶格肿胀随反位浓度的变化关系，结果表明，Lu₂Ti₂O₇出现非晶前的晶格肿胀主要由阳离子反位导致，而Lu₂TiO₅是无序的萤石结构，其辐照所导致的晶格肿胀不含阳离子反位的贡献，晶格肿胀程度较低。

Radiation Damage of Lu2Ti2O7 and Lu2TiO5 Ceramics Caused by Kr Ion Irradiation

Titanate are one of the important candidates for solidifying high-level radioactive nuclear waste (HLW) and lanthanide (Plutonium) due to its excellent physical and chemical durability. Polycrystalline Lu₂Ti₂O₇ and Lu₂TiO₅ ceramic materials were prepared by a conventional ceramic sintering process, then the samples were irradiated with 800 keV Kr2+ at room temperature, and were subsequently characterized by GIXRD method. In the two kinds of samples, lattice swelling was observed firstly, and then amorphization phase transition took place. However, the lattice swelling of Lu₂Ti₂O₇ is greater than that of Lu₂TiO₅. In addition, when Lu₂Ti₂O₇ and Lu₂TiO₅ were irradiated to a fluence of 2×10₁₄ ions/cm₂, the amorphous content of Lu₂TiO₅ sample reaches 95.54%, while the amorphous content of Lu₂Ti₂O₇ sample is only 74.66%. The first-principle was used to calculate the lattice swelling of Lu₂Ti₂O₇ with increasing of anti-sites concentration. The results show that the lattice swelling of Lu₂Ti₂O₇ before amorphization is mainly caused by the cation anti-sites. While the pristine Lu₂TiO₅ is a disordered fluorite structure, so that no cation anti-sites will contribute to the lattice swelling of Lu₂TiO during the ion irradiation process. Therefore, the lattice swelling of Lu₂TiO₅ is lower compared to that of Lu₂Ti₂O₇.