Complex structures of dense lithium: Electronic origin

31st International Conference on Equations of State for Matter

Degtyareva, V.F.^1

Institute of Solid State Physics of the Russian Academy of Sciences, Institutskaya Street 2, Chernogolovka, Moscow Region

142432, Russia^1

关键词: Ambient pressures;    Electronic behaviors;    Electronic configuration;    High-pressure form;    High-pressure phasis;    High-pressure structures;    Optical reflectivity;    Structural and physical properties;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/774/1/012003/pdf
DOI  :  10.1088/1742-6596/774/1/012003

来源: IOP

【 摘 要 】

Lithium - the lightest alkali metal exhibits unexpected structures and electronic behavior at high pressures. Like the heavier alkali metals, Li is bcc at ambient pressure and transforms first to fcc (at 7.5 GPa). The post-fcc high-pressure form Li-cI 16 (at 40-60 GPa) is similar to Na-cI 16 and related to more complex structures of heavy alkalis Rb-oC52 and Cs- oC84. The other high pressure phases for Li (oC88, oC40, oC24) observed at pressures up to 130 GPa are found only in Li. The different route of Li high-pressure structures correlates with its special electronic configuration containing the only 3 electrons (at 1s and 2s levels). Crystal structures for Li are analyzed within the model of Fermi sphere-Brillouin zone interactions. Stability of post-fcc structures for Li are supported by the Hume-Rothery arguments when new diffraction plains appear close to the Fermi level producing pseudogaps near the Fermi level and decreasing the crystal energy. The filling of Brillouin-Jones zones by electron states for a given structure defines the physical properties as optical reflectivity, electrical resistivity and superconductivity. To understand the complexity of structural and physical properties of Li above 60 GPa it is necessary to assume the valence electron band overlap with the core electrons and increase the valence electron count under compression.