We report a simple technique for the synthesis of uniaxially textured, metastable hexagonal close-packed-like uranium thin films with thicknesses between 175-2800 {\AA}. 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 \alpha-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 {\alpha}-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 {\gamma}-U(110) to hcp-U(00.1) to {\alpha}-U(001) displacive phase transition. Alternative transition pathways are discussed.

中文翻译：

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亚稳六方铀薄膜的结构和相变

我们报告了一种用于合成厚度在 175-2800 {\AA} 之间的单轴织构、亚稳六方密排状铀薄膜的简单技术。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，并且已经通过类似技术绘制了样品到正交α-U 的各种取向的时间相关转变。发现每个系统的最终晶体取向和发生转变的时间尺度取决于原始层的晶格参数。跃迁产物中没有 {\alpha}-U (001) 取向表明，这些层中的跃迁是由先前为立方 {\gamma}-U 提出的 [110] 横向声子模式以外的机制介导的(110) 到 hcp-U(00. 1) 到 {\alpha}-U(001) 位移相变。讨论了替代的过渡途径。