Elatresh Sabri F, Cai Weizhao, Ashcroft N W, Hoffmann Roald, Deemyad Shanti, Bonev Stanimir A
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853.
Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112.
Proc Natl Acad Sci U S A. 2017 May 23;114(21):5389-5394. doi: 10.1073/pnas.1701994114. Epub 2017 May 10.
The low-temperature crystal structure of elemental lithium, the prototypical simple metal, is a several-decades-old problem. At 1 atm pressure and 298 K, Li forms a body-centered cubic lattice, which is common to all alkali metals. However, a low-temperature phase transition was experimentally detected to a structure initially identified as having the stacking. This structure, proposed by Overhauser in 1984, has been questioned repeatedly but has not been confirmed. Here we present a theoretical analysis of the Fermi surface of lithium in several relevant structures. We demonstrate that experimental measurements of the Fermi surface based on the de Haas-van Alphen effect can be used as a diagnostic method to investigate the low-temperature phase diagram of lithium. This approach may overcome the limitations of X-ray and neutron diffraction techniques and makes possible, in principle, the determination of the lithium low-temperature structure (and that of other metals) at both ambient and high pressure. The theoretical results are compared with existing low-temperature ambient pressure experimental data, which are shown to be inconsistent with a phase for the low-temperature structure of lithium.
元素锂作为典型的简单金属，其低温晶体结构是一个存在了数十年的问题。在1个大气压和298K的条件下，锂形成体心立方晶格，这是所有碱金属共有的结构。然而，实验检测到在低温下会发生相变，转变为一种最初被认为具有 堆积结构。这种结构由奥弗豪泽于1984年提出，多次受到质疑但未得到证实。在此，我们对锂在几种相关结构中的费米面进行了理论分析。我们证明，基于德哈斯 - 范阿尔芬效应的费米面实验测量可作为一种诊断方法，用于研究锂的低温相图。这种方法可能克服X射线和中子衍射技术的局限性，原则上使得在常压和高压下确定锂的低温结构（以及其他金属的结构）成为可能。将理论结果与现有的低温常压实验数据进行了比较，结果表明这些数据与锂低温结构的 相不一致。
