Systematics in lanthanide and actinide solids
Systematics in lanthanide and actinide solids
复制标题
镧系和锕系固体的系统学
DOI：
10.1016/0925-8388(94)09000-9
复制
发表时间：
1995
影响因子：
6.2
通讯作者：
K. Gschneidner
中科院分区：
文献类型：
--
作者：
K. Gschneidner
镧系元素和锕系元素的广义相图已经问世了大约十年，并且这些已被证明对于理解这两个系列元素的相关系以及在缺乏实验数据时预测相的存在非常有用。检查这两个广义相图的相似点和不同点。系统学在镧系化合物系列中的应用有助于预测晶体结构（相关系）、熔点、生成焓和自由能。对这些数据的分析表明存在与其他价电子和/或成键电子的 4f 杂化。 4f 杂化很可能涉及费米表面上方的空 4f 能级，而不是填充的局部 4f 能级。系统学也已应用于锕系金属。由于实验数据主要限于 Th、U 和 Pu，并且由于早期锕系元素的价态从 3 变为 7，因此这些在镧系元素中非常成功的技术的实用性受到了限制。如果有更多关于锕及其合金系统的实验数据，我们对锕系合金和化合物的理解就可以取得更多进展。此外，由于应用系统学，人们认为所报告的 Ac 和 AcH2 晶格参数很可能是错误的。提出 f.c.c. 的正确晶格参数。 Ac金属为5.670 Å，比目前公认的值大约6.7%。
Generalized phase diagrams have been available for about ten years for both the lanthanides and actinides, and these have proven to be quite useful in understanding the phase relationships in the two series of elements and in predicting the existence of phases when experimental data are lacking. The two generalized phase diagrams are examined for their similarities and differences. The application of systematics in lanthanide compound series has been useful in predicting crystal structures (phase relationships), melting points, and enthalpies and free energies of formation. Analyses of these data indicate that there is 4f hybridization with the other valence and/or bonding electrons. It is most likely that the 4f hybridization involves the empty 4f level(s) just above the Fermi surface and not the filled localized 4f levels. Systematics has also been applied to the actinide metals. Since the experimental data are primarily limited to Th, U and Pu, and since the valence changes from 3 to 7 in the early actinides, the usefulness of these techniques, which have been so successful for the lanthanides, has been limited. If more experimental data were available for actinium and its alloy systems, much more progress could be made in our understanding of actinide alloys and compounds. In addition, as a result of applying systematics, it is thought that the lattice parameters reported for Ac and AcH2are quite likely to be wrong. It is proposed that the correct lattice parameter for f.c.c. Ac metal is 5.670 Å, about 6.7% larger than the value which has been accepted up to now.