Volume Contraction During Melting; Emphasis on Lanthanide and Actinide Metals
Volume Contraction During Melting; Emphasis on Lanthanide and Actinide Metals
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DOI：
10.1063/1.1677899
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发表时间：
1972
影响因子：
4.4
通讯作者：
L. Wittenberg;R. Dewitt
中科院分区：
文献类型：
--
作者：
L. Wittenberg;R. Dewitt
在熔化过程中的体积变化的审查表明，大多数金属表现出3.8%的平均体积增加在此相变。La、Pr、Nd和Np的体积增加非常小，而半金属加上铈和钚的体积增加是负的。基于粘性流的自由体积关系，计算出液体的密堆积结构V10，其几乎与许多密堆积金属，稀有气体固体Ar、Kr和H2O，碱金属Hg以及镧系金属La和Yb在熔点时的固体体积（Vs）相同。对于Bi、Ga、Ce、Pr、U和Pu，Vl0的值显着小于Vs。Bi，Ga和Pu的相图的检查显示，Vl0对应于在压力下形成的相的体积，在该点处熔化曲线的斜率变为零。形成小于Vs的Vl0的假设机制是半金属的紧密堆积和轻微的价态增加。
A review of the volume change during melting indicates that the majority of metals exhibits an average volume increase of 3.8% during this phase transformation. The volume increase is unusually small for La, Pr, Nd, and Np, and is negative for the semimetals plus cerium and plutonium. Based on a free‐volume relationship for viscous flow, a close‐packed structure for the liquid V l0 was calculated which was nearly the same as the volume of the solid (Vs) at the melting point for a number of close‐packed metals, the rare gas solids Ar, Kr, and Xe, the alkali metals, Hg, and the lanthanide metals La and Yb. The value of V l0 was significantly less than Vs for Bi, Ga, Ce, Pr, U, and Pu. Examination of the phase diagrams of Bi, Ga, and Pu revealed that V l0 corresponded to the volume of the phase formed under pressure at which point the slope of the melting curve became zero. The mechanisms postulated for the formation of V l0 smaller than Vs were closer‐packing for the semimetals and slight valence increases ...