Belin Renaud C, Martin Philippe M, Valenza Philippe J, Scheinost Andreas C
CEA, DEN, DEC, CEN Cadarache F-13108 Saint-Paul-Lez-Durance, France.
Inorg Chem. 2009 Jun 15;48(12):5376-81. doi: 10.1021/ic900369b.
Our works shows that the americium pyrochlore (241)Am(2)Zr(2)O(7) undergoes a phase transition to a defect-fluorite structure along with an unusual volume contraction when subjected to internal radiation from alpha-emitting actinides. Disorder relaxation proceeds through the simultaneous formation of cation antisites and oxygen Frenkel pairs. X-ray absorption spectroscopy at the Am-L(II) and the Zr-K edges reveals that Am-O polyhedra show an increasing disorder with increasing exposure. In contrast, the Zr-O polyhedral units remain highly ordered, while rotating along edges and corners, thereby reducing the structural strain imposed by the growing disorder around americium. We believe it is this particular property of the compound that provides the remarkable resistance to radiation (>9.4 x 10(18) alpha-decay events g(-1) or 0.80 dpa).
我们的研究表明，当受到α发射锕系元素的内辐射时，镅烧绿石（241）Am(2)Zr(2)O(7)会发生相变，转变为缺陷萤石结构，同时伴随着异常的体积收缩。无序弛豫通过阳离子反位和氧弗伦克尔对的同时形成而进行。在Am-L(II)和Zr-K边缘的X射线吸收光谱表明，随着辐照剂量的增加，Am-O多面体的无序度增加。相比之下，Zr-O多面体单元保持高度有序，同时沿边和角旋转，从而降低了镅周围不断增加的无序所施加的结构应变。我们认为正是该化合物的这一特殊性质赋予了其显著的抗辐射能力（>9.4×10(18)α衰变事件 g(-1)或0.80 dpa）。
