地质环境中放射性锆英石的结构演变及抗γ射线辐照能力

Structural Evolvement and the Capability of Resistance to γ-ray Irradiation for Zircon Originating from Geological Environment

为研究放射性核素固化介质备选矿物锆英石随地质年代演变的结构变化及抗γ射线辐照能力,以内蒙古白音宝力道花岗斑岩产出的锆英石(439.8±4.3 Ma)为研究对象,利用60Co源γ射线辐照装置对其进行γ射线辐照,借助多功能显微镜、阴极发光、背散射电子、电子探针、粉末X射线衍射、激光拉曼光谱和红外光谱等表征手段对γ射线辐照前后样品的物相、结构和微观形貌进行观察与分析,并对样品产出的地质背景和化学成分进行了研究。结果表明:内蒙古白音宝力道花岗斑岩所产出的锆英石系岩浆成因,经约4.4亿年的地质演变后,对UO2和ThO2的包容量仍为0.5798%,晶胞参数较标准样品发生了10-3nm量级的微小变化。样品经576 kGy的γ射线辐照后晶胞参数较辐照前发生了10-4nm量级的微小变化。说明锆英石在包容一定量U和Th的情况下具有较好的抗γ射线辐照能力,结构稳定。

In order to investigate the structural evolvement and the capability of resistance to γ-ray irradiation for zircon as mothball waste forms of radionuclide,the zircon crystals（439.8±4.3 Ma） were studied as investigative object,which were collected from the bayan bold granite-porphyry in the inner mongolia autonomous region.All the samples were irradiated using a 60Co γ-ray source with 576 kGy doses.Phases,structures and microstructures of the as-gained samples before and after γ-ray irradiation were characterized by means of a multi-functional microscope,cathodoluminescence（CL）,backscattered electron microprobe（BEM）,X-ray diffraction（XRD）,Raman spectroscopy（Raman）,infrared spectroscopy（IR） and scanning electron microscopy（SEM）,and so on.Moreover,the geological backgrounds and chemical compositions of zircons originating from natural rocks were analyzed as well.The results indicate that the as-gained crystals came from magmatic rock which undergone 439.8±4.3 million years geological evolvement and still contain UO2 and ThO2 with the contents of 0.5798%.The alteration of 10-3 nm magnitude in the crystal cell parameters was measured（cf the standard XRD card of zircon）.The irradiation on the crystalline samples using γ-ray induced to the alteration of 10-4nm magnitude for their crystal cell parameters.The conclusion shows that zircon crystals with a certain amount of UO2 and ThO2 have better structural stability for the γ-ray irradiation.