Negative expansions of interatomic distances in metallic melts
Negative expansions of interatomic distances in metallic melts
复制标题
金属熔体中原子间距离的负膨胀
DOI：
10.1073/pnas.1307967110
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发表时间：
2013-06-18
影响因子：
11.1
通讯作者：
Jiang, Jian-zhong
中科院分区：
文献类型：
--
作者：
Lou, Hongbo;Wang, Xiaodong;Jiang, Jian-zhong
当材料被加热时，通常它会膨胀。在这里，我们发现了一个总的趋势，中心原子和原子之间的平均距离在第一个最近的邻居壳层的合同几种金属熔体加热时。利用同步辐射X射线衍射技术和分子动力学模拟，我们阐明了这种异常是由温度影响的多面体团簇的重新分布引起的。在金属熔体中，随着温度的升高，高配位多面体有向低配位多面体演化的趋势。随着配位数的减少，多面体簇合物中中心原子与第一壳层原子之间的平均原子距离减小。这种现象是由不同尺寸的多面体组成的金属熔体的普遍特征。这一发现有助于理解无序材料的原子结构和热行为，并将引发更多的实验和理论研究液体，非晶合金，玻璃，铸造温度对结晶材料凝固过程的影响。
When a material is heated, generally, it dilates. Here, we find a general trend that the average distance between a center atom and atoms in the first nearest-neighbor shell contracts for several metallic melts upon heating. Using synchrotron X-ray diffraction technique and molecular dynamics simulations, we elucidate that this anomaly is caused by the redistribution of polyhedral clusters affected by temperature. In metallic melts, the high-coordinated polyhedra are inclined to evolve into low-coordinated ones with increasing temperature. As the coordination number decreases, the average atomic distance between a center atom and atoms in the first shell of polyhedral clusters is reduced. This phenomenon is a ubiquitous feature for metallic melts consisting of various-sized polyhedra. This finding sheds light on the understanding of atomic structures and thermal behavior of disordered materials and will trigger more experimental and theoretical studies of liquids, amorphous alloys, glasses, and casting temperature effect on solidification process of crystalline materials.