中文摘要：

钛酸盐Ln2TiO5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多晶正交结构Gd2TiO5陶瓷材料.样品经抛光后,在室温下用400 keV He＋和800 keV Kr2＋辐照.辐照后,样品结构变化利用掠入式X射线衍射（GIXRD）表征.结果发现：采用重离子Kr2＋辐照时,样品Gd2TiO5发生非晶化转变现象,从结晶相转变为非晶相; 而采用轻离子He＋辐照时,在辐照剂量为1.0×10^16 cm-2时,辐照样品几乎完全从正交结构转变为立方结构,另外,当He＋辐照剂量为5.0×10^16 cm-2,Gd2TiO5仍没有发生非晶化转变现象,但完全从正交结构转变成立方结构,同时,样品晶格体积收缩约3.0%.样品在高剂量He＋辐照下没有发生非晶化转变现象可归因于400 keV He＋辐照引起的强电子能损抑制了Gd2TiO5的非晶化转变过程.

英文摘要：

Titanate Ln2TiO5 can act as one of the important candidates for high-level radioactive nuclear waste（HLW）and dismantled plutonium due to their excellent physical and chemical durability.Polycrystalline pellets of Gadolinium titanate Gd2TiO5 with orthorhombic structure were irradiated at room temperature with 400 keV He＋ and 800 keV Kr2＋.Ion irradiation-induced microstructural evolution was characterized using grazing incidence X-ray diffraction（GIXRD）.Crystalline-to-amorphous transition was observed in orthorhombic Gd2TiO5 under 800 keV Kr2＋ irradiation.When irradiated with 400 keV He＋,the crystal structure of the irradiated Gd2TiO5 almost completely changed from an orthorhombic structure to a cubic fluorite structure at a fluence of 1.0×10^16 cm-2.When the ion irradiation dose was up to 5.0×10^16 cm-2,crystal structure transformation occurred completely,and no amorphization was observed due to the intense ionizing radiation inhibiting amorphization in orthorhombic Gd2TiO5.This structural transformation is accompanied by a decrease in molecular volume（or density increase）of approximately 3.0%.