论文标题
亚稳态六边形铀薄膜的结构和相变
Structure and Phase Transitions of Metastable Hexagonal Uranium Thin Films
论文作者
论文摘要
我们报告了一种简单的技术，用于合成单轴纹理的，亚稳定的六角形封闭式封闭式铀薄膜，厚度在175-2800Å之间。已经通过X射线衍射和反射率研究了层的初始结构和纹理，以及样品到正交$α$ -U的各种方向的时间依赖性过渡已通过相似技术映射。发现每个系统的最终晶体学方向以及发生过渡的时间尺度取决于原始层的晶格参数。过渡产品中的$α$ -U（001）取向的不存在表明，这些层中的过渡是由先前建议的[110]横向声音声子模式以外的其他机制介导的，该模式先前建议的是CubiC $γ$ -U（110）到HCP-U（00.1）至$α$ -U -U-a $ -u -u-u（00.1）的转移。讨论了替代性过渡途径。
We report a simple technique for the synthesis of uniaxially textured, metastable hexagonal close-packed-like uranium thin films with thicknesses between 175-2800 Å. The initial structure and texture of the layers have been studied via X-ray diffraction and reflectivity and the time-dependent transitions of the samples into various orientations of orthorhombic $α$-U have been mapped by similar techniques. The final crystallographic orientations of each system and the timescales on which the transitions occur are found to depend on the lattice parameters of the original layer. The absence of the $α$-U (001) orientation in the transition products suggests that the transitions in these layers are mediated by mechanisms other than the [110] transverse acoustic phonon mode previously suggested for the cubic $γ$-U(110) to hcp-U(00.1) to $α$-U(001) displacive phase transition. Alternative transition pathways are discussed.
