Lithium nitride is an inorganic compound with the chemical formula Li3N. It is the only stable alkali metal nitride. It is a reddish-pink solid with a high melting point.[1]
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 Crystal structure of lithium nitride.
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| Names | |
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| Preferred IUPAC name
Lithium nitride | |
Other names
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.043.144 |
| EC Number |
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| 1156 | |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| Li3N | |
| Molar mass | 34.83 g·mol−1 |
| Appearance | Red-purple or reddish-pink crystals or powder |
| Density | 1.270 g/cm3 |
| Melting point | 813 °C (1,495 °F; 1,086 K) |
| reacts | |
| log P | 3.24 |
| Structure | |
| see text | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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reacts with water to release ammonia |
| GHS labelling: | |
 
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| Danger | |
| H260, H314 | |
| P223, P231+P232, P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P335+P334, P363, P370+P378, P402+P404, P405, P501 | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Other anions
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Other cations
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Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation and handling
editLithium nitride is prepared by direct reaction of elemental lithium with nitrogen gas:[2]
- 6 Li + N2 → 2 Li3N
Instead of burning lithium metal in an atmosphere of nitrogen, a solution of lithium in liquid sodium metal can be treated with N2.
Lithium nitride must be protected from moisture as it reacts violently with water to produce ammonia:
- Li3N + 3 H2O → 3 LiOH + NH3
Structure and properties
edit- alpha-Li3N (stable at room temperature and pressure) has an unusual crystal structure that consists of two types of layers: one layer has the composition Li2N− contains 6-coordinate N centers and the other layer consists only of lithium cations.[3]
Two other forms are known:
- beta-Li3N, formed from the alpha phase at 0.42 GPa has the sodium arsenide (Na3As) structure;
- gamma-Li3N (same structure as lithium bismuthide Li3Bi) forms from the beta form at 35 to 45 GPa.[4]
Lithium nitride shows ionic conductivity for Li+, with a value of c. 2×10−4 Ω−1cm−1, and an (intracrystal) activation energy of c. 0.26 eV (c. 24 kJ/mol). Hydrogen doping increases conductivity, whilst doping with metal ions (Al, Cu, Mg) reduces it.[5][6] The activation energy for lithium transfer across lithium nitride crystals (intercrystalline) has been determined to be higher, at c. 68.5 kJ/mol.[7] The alpha form is a semiconductor with band gap of c. 2.1 eV.[4]
Reactions
editReacting lithium nitride with carbon dioxide results in amorphous carbon nitride (C3N4), a semiconductor, and lithium cyanamide (Li2CN2), a precursor to fertilizers, in an exothermic reaction.[8][9]
Under hydrogen at around 200°C, Li3N will react to form lithium amide.[10]
- Li3N + 2 H2 → 2LiH + 2LiNH2
At higher temperatures it will react further to form ammonia and lithium hydride.
- LiNH2 + H2 → LiH + NH3
Lithium imide can also be formed under certain conditions. Some research has explored this as a possible industrial process to produce ammonia since lithium hydride can be thermally decomposed back to lithium metal.
Lithium nitride has been investigated as a storage medium for hydrogen gas, as the reaction is reversible at 270 °C. Up to 11.5% by weight absorption of hydrogen has been achieved.[11]
References
edit- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ E. Döneges "Lithium Nitride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, New York. Vol. 1. p. 984.
- ^ Barker M. G.; Blake A. J.; Edwards P. P.; Gregory D. H.; Hamor T. A.; Siddons D. J.; Smith S. E. (1999). "Novel layered lithium nitridonickelates; effect of Li vacancy concentration on N co-ordination geometry and Ni oxidation state". Chemical Communications (13): 1187–1188. doi:10.1039/a902962a.
- ^ a b Walker, G, ed. (2008). Solid-State Hydrogen Storage: Materials and Chemistry. §16.2.1 Lithium nitride and hydrogen:a historical perspective.
- ^ Lapp, Torben; Skaarup, Steen; Hooper, Alan (October 1983). "Ionic conductivity of pure and doped Li3N". Solid State Ionics. 11 (2): 97–103. doi:10.1016/0167-2738(83)90045-0.
- ^ Boukamp, B. A.; Huggins, R. A. (6 September 1976). "Lithium ion conductivity in lithium nitride". Physics Letters A. 58 (4): 231–233. Bibcode:1976PhLA...58..231B. doi:10.1016/0375-9601(76)90082-7.
- ^ Boukamp, B. A.; Huggins, R. A. (January 1978). "Fast ionic conductivity in lithium nitride". Materials Research Bulletin. 13 (1): 23–32. doi:10.1016/0025-5408(78)90023-5.
- ^ Yun Hang Hu, Yan Huo (12 September 2011). "Fast and Exothermic Reaction of CO2 and Li3N into C–N-Containing Solid Materials". The Journal of Physical Chemistry A. 115 (42). The Journal of Physical Chemistry A 115 (42), 11678-11681: 11678–11681. Bibcode:2011JPCA..11511678H. doi:10.1021/jp205499e. PMID 21910502.
- ^ Darren Quick (21 May 2012). "Chemical reaction eats up CO2 to produce energy...and other useful stuff". NewAtlas.com. Retrieved 17 April 2019.
- ^ Goshome, Kiyotaka; Miyaoka, Hiroki; Yamamoto, Hikaru; Ichikawa, Tomoyuki; Ichikawa, Takayuki; Kojima, Yoshitsugu (2015). "Ammonia Synthesis via Non-Equilibrium Reaction of Lithium Nitride in Hydrogen Flow Condition". Materials Transactions. 56 (3): 410–414. doi:10.2320/matertrans.M2014382.
- ^ Ping Chen; Zhitao Xiong; Jizhong Luo; Jianyi Lin; Kuang Lee Tan (2002). "Interaction of hydrogen with metal nitrides and amides". Nature. 420 (6913): 302–304. Bibcode:2002Natur.420..302C. doi:10.1038/nature01210. PMID 12447436. S2CID 95588150.
See also
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