【摘要】 摘要利用高温原位XAFS技术研究了半金属Sb在固态和熔态时的局域结构特点。结果表明在893K高温时固态Sb的局域结构与常温(298K)时晶态Sb的相似,但其热无序度较大。随着温度再升高20K到熔化后的913K时,熔态Sb的主配位峰形状有较大变化,其强度仅为熔化前的70%左右。这一结果表明熔化导致Sb的结构无序显著增加,我们认为这是熔态Sb中Sb原子的第一近邻配位的大部分共价键断裂造成的。模型无关的ReverseMonteCarlo方法拟合计算结果也表明熔化引起Sb样品的第一近邻配位数由固态的6增加到熔态的9。当温度升高至1058K时,Sb样品的Sb原子的径向结构函数曲线的形状与913K的Sb样品的相似,说明在熔化后的100至200K的温度范围,熔态Sb中Sb原子的局域结构差别不大。更多还原

【Abstract】 The in-situ XAFS technique has been employed to study the local structures of semi-metal Sb in the pre-molten and liquid states. The results reveal that the local structure of the pre-molten Sb at the temperature of 893 K is similar to that of crystalline Sb at 298 K, except that the thermal disorder of the former is relatively larger. With the temperature increasing to 913 K ( melting point Tm= 903 K for the element Sb ) , the main peak intensity of radial distribution function of the molten Sb ( 913 K) is strongly reduced to about 70% of the pre-molten Sb ( 893 K ) . This indicates that the structural disorder of the liquid Sb increases remarkably during the solid-liquid tran- sition, which can be attributed to the fact that the covalent bonds of the first shell are mostly broken in liquid Sb. The results obtained from the model-independent reverse Monte Carlo calculation in the process of solid-liquid transition shows that the coordination number of the first neighbor around Sb atoms increases from 6 to 9. As the temperature further rises to 1058 K, the radial structural function of Sb ( 1058 K ) indicates that liquid Sb possesses a similar local structure in the temperature range of 100—200 K beyond the melting point.更多还原