# Chemicals/Lithiums

This spectrograph shows the visual spectral lines of lithium. Credit: T c951.

Lithiums is a lecture from the school of chemistry about the various lithiums that occur or are manufactured.

## Alkali metal minerals

This is a magnesium-lithium phase diagram. Credit: T. Massalski, H. Okamoto, P. Subramanian, L. Kacprzak, ASM International.

As indicated in the magnesium-lithium phase diagram on the left, lithium occurs in the same crystal structure at lower temperatures as it does up to melting temperature. This is the bcc phase (α-Li).

"Native lithium is rare in nature. Most of the lithium is extracted from the mining [of] spodumene."[1]

## Lithiophosphates

Lithiophosphate has the chemical formula Li3PO4, with 37.5 at % lithium.[2]

## Violets

"Violet satellite bands are caused by those lithium atoms which undergo an optical transition while a helium atom is nearby."[3]

## Nucleosynthesis

${\displaystyle \mathrm {_{1}^{3}T} +\mathrm {_{2}^{4}He} \rightarrow \mathrm {_{3}^{7}Li} +\gamma }$  + ? MeV
${\displaystyle \mathrm {_{4}^{7}Be} +n^{0}\rightarrow \mathrm {_{3}^{7}Li} +p^{+}}$

## Glasses

"In the other series of glasses, Li, Na, and K, in particular, that can be formed out to x=0.75, the IR spectra clearly show that this structural group becomes the dominant group in the glass at this composition [4], [5] and [43]."[4]

## Glaciers

Main sources: Rocks/Glaciers and Glaciers

"Taylor Valley glaciers have the lowest lithium concentrations and lightest δ7Li values in the McMurdo Dry Valleys aquatic system."[5]

"The δ7Li ratios of the glacial snow are among the lightest values observed in surface and groundwater samples (+0.8 to +2.9‰) and are unlike seawater (+30.8‰) (Tomascak, 2004; Rosner et al., 2007). This suggests that marine aerosol or marine-derived salts are not the primary sources of lithium to the glacier surfaces [...] Generally, geologic materials are isotopically lighter than natural water samples because of the preferential retention of 6Li in the solid phase. Despite this general relationship, Taylor Valley glacier snow samples have δ7Li signatures more like granite and rhyolite, which range from −1.2 to +8.0‰ (Tomascak, 2004). Although this wide range of Li isotopic values for granite does not conclusively mean the source to the glaciers is felsic rock, the snow samples are extremely light and resemble aluminosilicates. We therefore conclude that the major source of Li in the glacier ice is likely the dissolution of silicate materials."[5]

## Sun

Main sources: Stars/Sun and Sun (star)

"[T]he standard solar models have enjoyed tremendous success recently in terms of agreement between the predicted outer structure and the results from helioseismology[, but] some observed properties of the Sun still defy explanation, such as the degree of Li depletion" [the "solar Li abundance is roughly a factor of 200 below the meteoritic abundance"].[6]

## Heliogony

Main sources: Stars/Sun/Heliogony and Heliogony

"Using ESO’s very successful HARPS spectrograph, a team of astronomers has found that Sun-like stars which host planets have destroyed their lithium much more efficiently than planet-free stars. This finding does not only shed light on the low levels of this chemical element in the Sun, solving a long-standing mystery, but also provides astronomers with a very efficient way to pick out the stars most likely to host planets. It is not clear what causes the lithium to be destroyed. The general idea is that the planets or the presence of the protoplanetary disc disturb the interior of the star, bringing the lithium deeper down into the star than usual, into regions where the temperature is so hot that it is destroyed."[7]

## Red giants

Main sources: Stars/Giants/Reds and Red giants

In some 824 red giant stars, the Li I 670.78 nm line was detected in several stars, "but only the five objects ... presented a strong line."[8]

"The lithium content of red-giant stars is highly variable (Wallerstein and Conti 1969). The largest amounts of lithium are found in three carbon stars, WZ Cas, WX Cyg, and T Ara, being of the order of 10-2 of calcium. ... Boesgaard (1970) has found a similar high lithium abundance in the S star T Sgr. This is a higher ratio of lithium to calcium than is found in T Tauri stars or in meteorites."[9]

## Brown dwarfs

Some of the incontrovertible brown dwarf substellar objects are "identified by the presence of the 670.8 nm lithium [I] line. The most notable of these objects was Gliese 229B, which was found to have a temperature and luminosity well below the stellar range. Remarkably, its near-infrared spectrum clearly exhibited a methane absorption band at 2 micrometres, a feature that had previously only been observed in gas giant atmospheres and the atmosphere of Saturn's moon, Titan. Methane absorption is not expected at the temperatures of main-sequence stars. This discovery helped to establish yet another spectral class even cooler than L dwarfs known as "T dwarfs" for which Gl 229B is the prototype. ... Lithium is generally present in brown dwarfs and not in low-mass stars. [T]he presence of the lithium line in a candidate brown dwarf's spectrum is a strong indicator that it is indeed substellar. The use of lithium to distinguish candidate brown dwarfs from low-mass stars is commonly referred to as the lithium test ... Some brown dwarfs emit X-rays; and all "warm" dwarfs continue to glow tellingly in the red and infrared spectra until they cool to planetlike temperatures (under 1000 K)."[10]

## Cosmogony

Main source: Cosmogony

"From the cosmogony point of view, there can be many different pathways to form a planet, and this casts some doubt that planet formation could be either an adequate physical quantity or a useful observational criterion to define what a planet is. In practice, it is convenient to adopt a planet definition that heavily relies on the mass of the object because the mass can be either measured directly or it has an impact on observable quantities such as surface gravity. For solar composition the boundary [brown dwarfs] BDs and planets is determined by deuterium fusion, which ceases to be stable at around 13 Jupiter masses [18, 19]. Just as the lithium test has effectively been applied as a tool to distinguish between very low-mass stars and BDs [6, 43, 46, 62, 72], the deuterium test has been proposed to distinguish between BDs and planets [9] but it has not been carried out yet because it is observationally very challenging. This important observational test may have to wait for the advent of the 30-meter class generation of ground-based telescopes such as the European Extremely Large Telescope or the American Thirty Meter Telescope. Particularly promising targets are nearby late-T dwarfs with effective temperatures around 500K that appear to have peculiar properties indicative of young age and planetary mass, such as for example ULASJ1335+11 [37]."[11]

"A possible link between lithium depletion, rotational history and the presence of exoplanets has been explored for solar-type main-sequence stars [15]."[11]

## Recent history

Main sources: History/Recent and Recent history

The recent history period dates from around 1,000 b2k to present.

"Lithium was discovered in 1817 by Johann Arfvedson in Stockholm, Sweden. The name is derived from the Greek, [λίθος] (lithos), meaning stone."[12]

## Hypotheses

Main source: Hypotheses
1. Lithium can be produced by muon induced fusion.

## References

1. Shanghai Xuanshi Machinery Co., Ltd. (2011). "Xuanshi". Shanghai, PRC: Shanghai Xuanshi Machinery Co., Ltd. Retrieved 2015-08-22.
2. Willard Lincoln Roberts, George Robert Rapp, Jr., and Julius Weber (1974). Encyclopedia of Minerals. 450 West 33rd Street, New York, New York 10001 USA: Van Nostrand Reinhold Company. p. 693. ISBN 0-442-26820-3.
3. G. D. Mahan (April 24, 1972). "Violet satellite bands in the spectra of Li perturbed by He". Physics Letters A 39 (2): 145-6. doi:10.1016/0375-9601(72)91056-0. Retrieved 2013-03-23.
4. Jaephil Cho, Steve W Martin (March 2002). "Infrared spectroscopy of glasses and polycrystals in the series xCs2S+(1−x)B2S3". Journal of non-crystalline solids 298 (2-3): 176-92. Retrieved 2013-08-28.
5. RA Witherow, WB Lyons, GM Henderson (2010). "Lithium isotopic composition of the McMurdo Dry Valleys aquatic systems". Chemical Geology 275: 139-47. doi:10.1016/j.chemgeo.2010.04.017. Retrieved 2014-09-20.
6. Jeremy R. King, Constantine P. Deliyannis, and Merchant Boesgaard (April 1, 1997). "The 9Be Abundances of α Centauri A and B and the Sun: Implications for Stellar Evolution and Mixing". The Astrophysical Journal 478 (2): 778. Retrieved 2012-07-11.
7. L. Calçada (11 November 2009). "Burning lithium inside a star (artist's impression)". European Southern Observatory. Retrieved 2014-07-31.
8. L. Monaco, S. Villanova, C. Moni Bidin, G. Carraro, D. Geisler, P. Bonifacio, O. A. Gonzalez, M. Zoccali and L. Jilkova (May 2011). "Lithium-rich giants in the Galactic thick disk". Astronomy & Astrophysics 529 (5): 10. doi:10.1051/0004-6361/201016285.
9. A. G. W. Cameron and W. A. Fowler (February 1971). "Lithium and the s-PROCESS in Red-Giant Stars". The Astrophysical Journal 164 (02): 111-4. doi:10.1086/150821. Retrieved 2013-08-01.
10. "Brown dwarf, In: Wikipedia". San Francisco, California: Wikimedia Foundation, Inc. June 16, 2012. Retrieved 2012-07-11.
11. E. L. Martín (November 2012). "Exoplanet plenitude". Advances in Astronomy and Space Physics 2 (11): 109-13. Retrieved 2013-12-23.
12. Mysterioso (26 July 2014). "The periodic table/Lithium, In: Wikiversity". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2016-08-22.