Lithium nitride

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Lithium nitride
Unit cell ball and stick model of lithium nitride
Names
Preferred IUPAC name
Lithium nitride
Other names
Trilithium nitride
Identifiers
3D model (JSmol)
ChEBI
ECHA InfoCard 100.043.144
EC Number 247-475-2
Properties
Li3N
Molar mass 34.83 g/mol
Appearance red, purple solid
Density 1.270 g/cm3
Melting point 813 °C (1,495 °F; 1,086 K)
reacts
log P 3.24
Structure
see text
Hazards
Main hazards reacts with water to release ammonia
Related compounds
Other anions
Lithium oxide
Other cations
Sodium nitride
Related compounds
Lithium amide Lithium imide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Lithium nitride is a compound with the formula Li3N. It is the only stable alkali metal nitride. The solid is a red or purple color and has a high melting point.[1]

Preparation and handling[edit]

Lithium nitride is prepared by direct combination 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 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 sheet has the composition Li2N contains 6-coordinate N centers and the other sheet consists only of lithium cations.[3] Two other forms are known: beta-Lithium nitride, formed from the alpha phase at 4,200 bars (4,100 atm) has the Sodium arsenide (Na3As) structure; gamma-Lithium nitride (same structure as Li3Bi) forms from the beta form at 35 to 45 gigapascals (350,000 to 440,000 atm).[4]

Lithium nitride shows ionic conductivity for Li+, with a value of c. 2x10−4Ω−1cm−1, and an (intracrystal) activation energy of c. 0.26eV (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. 2.1eV.[4]

Reaction with hydrogen at under 300 °C (0.5MPa pressure) produces Lithium hydride and Lithium amide.[8]

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.[9]

References[edit]

  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9. 
  2. ^ E. Döneges "Lithium Nitride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. 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". Chem. Commun. (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 Sep 1976), "Lithium ion conductivity in lithium nitride", Physics Letters A, 58 (4): 231–233, 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. ^ Goshome1, Kiyotaka; Miyaoka2, Hiroki; Yamamoto1, Hikaru; Ichikawa3, Tomoyuki; Ichikawa1, Takayuki; Kojima1, 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 
  9. ^ 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. PMID 12447436. doi:10.1038/nature01210. 

See also[edit]