A first-principles comparative study of lithium, sodium, and magnesium storage in pure and gallium-doped germanium: Competition between interstitial and substitutional sites.

Title A first-principles comparative study of lithium, sodium, and magnesium storage in pure and gallium-doped germanium: Competition between interstitial and substitutional sites.
Authors F. Legrain; S. Manzhos
Journal J Chem Phys
DOI 10.1063/1.4973841
Abstract

Thermodynamics and kinetics of Li, Na, and Mg storage in Ge are studied ab initio. The most stable configurations can consist of tetrahedral, substitutional, or a combination of the two types of sites. In the dilute limit, Li and Na prefer interstitial, while Mg prefers substitutional sites. At higher concentrations of Li, Na, and Mg, there is a combination of interstitial and substitutional sites. This is an important finding, as most previous ab initio studies of alloying type electrode materials ignored substitutional sites. Insertion energies computed at dilute concentration (x = 1/64) show that Na and Mg insertion are not thermodynamically favored in Ge vs. the formation of bulk Na and Mg, as opposed to Li insertion which is favored. We investigate the effect of p-doping of Ge (with Ga) on the thermodynamics and find that it considerably lowers the defect formation energies associated with the insertion of Li/Na/Mg at tetrahedral sites. On the other hand, the energetics associated with Li/Na/Mg insertion at substitutional sites are not significantly affected. In addition, we compute the migration energy barriers for Li/Na/Mg diffusion between two tetrahedral sites (0.38/0.79/0.66 eV), between two substitutional sites (0.77/0.93/1.83 eV), and between two sites of different types (2.15/1.75/0.85 eV).

Citation F. Legrain; S. Manzhos.A first-principles comparative study of lithium, sodium, and magnesium storage in pure and gallium-doped germanium: Competition between interstitial and substitutional sites.. J Chem Phys. 2017;146(3):034706. doi:10.1063/1.4973841

Related Elements

Germanium

See more Germanium products. Germanium (atomic symbol: Ge, atomic number: 32) is a Block P, Group 14, Period 4 element with an atomic weight of 72.63. Germanium Bohr ModelThe number of electrons in each of germanium's shells is 2, 8, 18, 4 and its electron configuration is [Ar] 3d10 4s2 4p2. The germanium atom has a radius of 122.5 pm and a Van der Waals radius of 211 pm. Germanium was first discovered by Clemens Winkler in 1886. In its elemental form, germanium is a brittle grayish white semi-metallic element. Germanium is too reactive to be found naturally on Earth in its native state. High Purity (99.999%) Germanium (Ge) MetalIt is commercially obtained from zinc ores and certain coals. It is also found in argyrodite and germanite. It is used extensively as a semiconductor in transitors, solar cells, and optical materials. Other applications include acting an alloying agent, as a phosphor in fluorescent lamps, and as a catalyst. The name Germanium originates from the Latin word "Germania" meaning "Germany."

Lithium

Lithium Bohr ModelSee more Lithium products. Lithium (atomic symbol: Li, atomic number: 3) is a Block S, Group 1, Period 2 element with an atomic weight of 6.94. The number of electrons in each of Lithium's shells is [2, 1] and its electron configuration is [He] 2s1. The lithium atom has a radius of 152 pm and a Van der Waals radius of 181 pm. Lithium was discovered by Johann Arvedson in 1817 and first isolated by William Thomas Brande in 1821. The origin of the name Lithium comes from the Greek wordlithose which means "stone." Lithium is a member of the alkali group of metals. It has the highest specific heat and electrochemical potential of any element on the period table and the lowest density of any elements that are solid at room temperature. Elemental LithiumCompared to other metals, it has one of the lowest boiling points. In its elemental form, lithium is soft enough to cut with a knife its silvery white appearance quickly darkens when exposed to air. Because of its high reactivity, elemental lithium does not occur in nature. Lithium is the key component of lithium-ion battery technology, which is becoming increasingly more prevalent in electronics.

Magnesium

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Sodium

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Gallium

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