lithium nitride

Lithium nitride is prepared by direct reaction of elemental lithium with nitrogen gas: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.

:{{chem2|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 {{chem2|N2}}.

Lithium nitride is an extremely strong base, so it must be protected from moisture as it reacts violently with water to produce ammonia:

:{{chem2|Li3N + 3 H2O → 3 LiOH + NH3}}

• alpha-{{chem2|Li3N}} (stable at room temperature and pressure) has an unusual crystal structure that consists of two types of layers: one layer has the composition {{chem2|Li2N−}} contains 6-coordinate N centers and the other layer consists only of lithium cations.{{cite journal |author1=Barker M. G. |author2=Blake A. J. |author3=Edwards P. P. |author4=Gregory D. H. |author5=Hamor T. A. |author6=Siddons D. J. |author7=Smith S. E. | journal = Chemical Communications | year = 1999 | pages = 1187–1188 | doi = 10.1039/a902962a | title = Novel layered lithium nitridonickelates; effect of Li vacancy concentration on N co-ordination geometry and Ni oxidation state | issue = 13}}

Two other forms are known:

• beta-{{chem2|Li3N}}, formed from the alpha phase at 0.42 GPa has the sodium arsenide ({{chem2|Na3As}}) structure;
• gamma-{{chem2|Li3N}} (same structure as lithium bismuthide {{chem2|Li3Bi}}) forms from the beta form at 35 to 45 GPa.{{cite book | title =Solid-State Hydrogen Storage: Materials and Chemistry| editor-first = G| editor-last = Walker| at = §16.2.1 Lithium nitride and hydrogen:a historical perspective|year = 2008}}

Lithium nitride shows ionic conductivity for {{chem2|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.{{cite journal | journal = Solid State Ionics| volume = 11| issue = 2| date = October 1983| pages = 97–103| title = Ionic conductivity of pure and doped Li₃N| first1 = Torben |last1 = Lapp |first2= Steen|last2= Skaarup|first3 = Alan|last3=Hooper|doi = 10.1016/0167-2738(83)90045-0}}{{cite journal | title = Lithium ion conductivity in lithium nitride| first1 = B. A. |last1 = Boukamp|first2= R. A. |last2 = Huggins| doi = 10.1016/0375-9601(76)90082-7 |journal = Physics Letters A| volume = 58| issue =4| date =6 September 1976|pages = 231–233| bibcode = 1976PhLA...58..231B}} The activation energy for lithium transfer across lithium nitride crystals (intercrystalline) has been determined to be higher, at c. 68.5 kJ/mol.{{cite journal | journal = Materials Research Bulletin| volume = 13| issue = 1| date = January 1978| pages = 23–32| title = Fast ionic conductivity in lithium nitride| first1 = B. A. | last1 = Boukamp| first2= R. A.|last2 = Huggins| doi = 10.1016/0025-5408(78)90023-5}} The alpha form is a semiconductor with band gap of c. 2.1 eV.

Reacting lithium nitride with carbon dioxide results in amorphous carbon nitride ({{chem2|C3N4}}), a semiconductor, and lithium cyanamide ({{chem2|Li2CN2}}), a precursor to fertilizers, in an exothermic reaction.{{cite journal|title=Fast and Exothermic Reaction of CO₂ and Li₃N into C–N-Containing Solid Materials |journal=The Journal of Physical Chemistry A |volume=115 |issue=42 |pages=11678–11681 |publisher=The Journal of Physical Chemistry A 115 (42), 11678-11681 |author=Yun Hang Hu, Yan Huo |date=12 September 2011 |doi=10.1021/jp205499e |pmid=21910502 |bibcode=2011JPCA..11511678H}}{{cite web|url=https://newatlas.com/co2-li3n-reaction/22620/ |title=Chemical reaction eats up CO₂ to produce energy...and other useful stuff |publisher=NewAtlas.com |author=Darren Quick |date=21 May 2012 |access-date=17 April 2019}}

Under hydrogen at around 200°C, Li₃N will react to form lithium amide.{{cite journal |last1=Goshome |first1=Kiyotaka |last2=Miyaoka |first2=Hiroki |last3=Yamamoto |first3=Hikaru |last4=Ichikawa |first4=Tomoyuki |last5=Ichikawa |first5=Takayuki |last6=Kojima |first6=Yoshitsugu |year=2015 |title=Ammonia Synthesis via Non-Equilibrium Reaction of Lithium Nitride in Hydrogen Flow Condition |journal=Materials Transactions |volume=56 |pages=410–414 |doi=10.2320/matertrans.M2014382 |doi-access=free |number=3}}

:{{chem2|Li3N + 2 H2 → 2LiH + LiNH2}}

At higher temperatures it will react further to form ammonia and lithium hydride.

:{{chem2|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.{{cite journal |author1=Ping Chen |author2=Zhitao Xiong |author3=Jizhong Luo |author4=Jianyi Lin |author5=Kuang Lee Tan |year=2002 |title=Interaction of hydrogen with metal nitrides and amides |journal=Nature |volume=420 |issue=6913 |pages=302–304 |bibcode=2002Natur.420..302C |doi=10.1038/nature01210 |pmid=12447436 |s2cid=95588150}}

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{{Lithium compounds}}

{{Nitrides}}

Category:Nitrides

Category:Lithium compounds

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