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]

Lithium nitride
Unit cell ball and stick model of lithium nitride
__ Li+     __ N3−

Crystal structure of lithium nitride.
Names
Preferred IUPAC name
Lithium nitride
Other names
  • Trilithium azanide
  • Trilithium nitride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.043.144 Edit this at Wikidata
EC Number
  • 247-475-2
1156
  • InChI=1S/3Li.N
    Key: IDBFBDSKYCUNPW-UHFFFAOYSA-N
  • InChI=1S/3Li.N/q;;+1;-1
    Key: AJUFTLIHDBAQOK-UHFFFAOYSA-N
  • [Li]N([Li])[Li]
  • [Li+].[Li][N-][Li]
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
reacts with water to release ammonia
GHS labelling:
GHS02: FlammableGHS05: Corrosive
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)
NFPA 704 four-colored diamondHealth (blue): no hazard codeFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
0
2
Related compounds
Other anions
Other cations
Related compounds
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

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Lithium 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

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  • 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

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Reacting 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

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  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  2. ^ 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.
  3. ^ 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.
  4. ^ a b Walker, G, ed. (2008). Solid-State Hydrogen Storage: Materials and Chemistry. §16.2.1 Lithium nitride and hydrogen:a historical perspective.
  5. ^ 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.
  6. ^ 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.
  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.
  8. ^ 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.
  9. ^ Darren Quick (21 May 2012). "Chemical reaction eats up CO2 to produce energy...and other useful stuff". NewAtlas.com. Retrieved 17 April 2019.
  10. ^ 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.
  11. ^ 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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