D-D中子辐照单晶TiO_2的损伤特性  

D-D neutron irradiation effects on single-crystal TiO_2

作　　者：许楠楠[1] 李公平[1,2] 王云波[1] 钟火平[1] 李天晶[1] 龚恒凤 王宝义[3] 李卓昕[3] 

机构地区：[1]兰州大学核科学与技术学院,兰州730000 [2]山东大学晶体材料国家重点实验室,济南250001 [3]中国科学院高能物理研究所,北京100049

出　　处：《核技术》2012年第2期98-103,共6页Nuclear Techniques

基　　金：山东大学晶体材料国家重点实验室基金(KF0901);兰州大学自然科学类中央高校基本科研专项(860452)资助

摘　　要：利用兰州大学强流中子发生器出射的单能D-D中子对单晶TiO2(金红石相)进行辐照,分别测量了样品的正电子寿命谱及XRD谱。中子辐照会在样品内部产生大量的空位缺陷,由于晶格中Ti原子的位移阈能约为O原子的2倍,因此中子辐照在样品内部产生的空位缺陷以氧空位(VO)为主。结果表明,单晶内部捕获正电子的陷阱Ti空位(VTi)在中子辐照后电子密度增大,可能与Ti空位周围O空位的引入有关,O空位的出现减弱了Ti空位处的库仑排斥作用,使空位体积减少。后续测试的XRD也得到相同的结果,样品由于中子辐照而在c轴方向的晶面间距发生变化,并导致单晶TiO2的结晶度变差。Rutile single-crystal TiO2 were irradiated by 2.5 MeV neutrons from D-D reaction on a neutron generator at Lanzhou University. Positron annihilation lifetime spectra and X-ray diffraction （XRD） patterns of the irradiated samples were compared with those of the virgin. Considering the fact that the threshold displacement energy of titanium atoms is almost two times of that of oxygen atoms, more oxygen vacancies （Vo） would be produced than that of titanium vacancies （VTi） under the neutron irradiation. Lifetime results indicated that the irradiated samples had larger electron density of titanium vacancies than the virgin rutile, as a result of increased oxygen vacancies surrounding the Ti vacancy, because of the coulombic repulsion. From the XRD results, distance along the c-axis shrank slightly and the crystallinity became weaker after the neutron irradiation.

关 键 词：单晶TiO2 D—D中子 辐照损伤 正电子 

分 类 号：O483[理学—固体物理]