Structural Signature of beta-Relaxation in La-Based Metallic Glasses
Structural Signature of beta-Relaxation in La-Based Metallic Glasses
复制标题
La 基金属玻璃中 β-弛豫的结构特征
DOI：
10.1021/acs.jpclett.8b02013
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发表时间：
2018
影响因子：
5.7
通讯作者：
Jiang J. Z.
中科院分区：
文献类型：
--
作者：
Wang X. D.;Zhang J.;Xu T. D.;Yu Q.;Cao Q. P.;Zhang D. X.;Jiang J. Z.
二次β弛豫是玻璃态材料的一个固有特征。然而，它的结构起源仍然没有得到很好的理解。本文报道了La_（50）Al_（15）Ni_（35）和La_（50）Al_（15）Cu_（35）金属玻璃的β弛豫主要依赖于局域笼中小Ni和Cu原子的振动。利用先进的同步辐射X射线技术和理论计算，阐明了壳层中含有较多较大La原子的三角锥状多面体有利于中心Ni原子的局域振动，从而导致明显的β-弛豫事件.与此相反，笼内振动的铜原子在某种程度上抑制了更多的壳层铜原子的出现。然而，与Ni相比，它们可以容易地扩散出笼，从而触发α-弛豫的开始。这一工作为从局域原子堆积和动力学角度理解MG和其他无序材料的不同结构弛豫行为提供了一条途径。
The secondary β-relaxation is an intrinsic feature in glassy materials. However, its structural origin is still not well understood. Here we report that the β-relaxations in La50Al15Ni35and La50Al15Cu35metallic glasses (MGs) mainly depend on the vibration of small Ni and Cu atoms in local cages. By using advanced synchrotron X-ray techniques and theoretical calculations, we elucidate that the tricapped-trigonal-prism-like polyhedra with more large La atoms in shells favor the local vibration of center Ni atoms, leading to the pronounced β-relaxation event. In contrast, the in-cage vibration of Cu atoms is somehow suppressed by the appearance of more shell Cu atoms. Nevertheless, they could easily diffuse out of the cages compared with Ni, thus triggering the onset of α-relaxation. This work provides a pathway to understand the different structural relaxation behaviors in MGs and other disordered materials from their local atomic packing and dynamics points of view.