Chemistry:Lithium iridate
| |||
![]() | |||
![]() Crystal structure of α-Li2IrO3 with Ir shown in yellow, Li in purple and O in red
| |||
Names | |||
---|---|---|---|
Preferred IUPAC name
Lithium iridate | |||
Identifiers | |||
3D model (JSmol)
|
|||
| |||
| |||
Properties | |||
Li2IrO3 | |||
Appearance | Black crystals | ||
Structure | |||
Monoclinic, C2/m[2] | |||
a = 5.1633(2) Å, b = 8.9294(3) Å, c = 5.1219(2) Å α = 90°, β = 109.759(3)°, γ = 90°
| |||
Formula units (Z)
|
4 | ||
Related compounds | |||
Other anions
|
Lithium ruthenate, lithium platinate | ||
Other cations
|
Sodium iridate | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
![]() ![]() ![]() | |||
Infobox references | |||
Lithium iridate, Li2IrO3, is a chemical compound of lithium, iridium and oxygen. It forms black crystals with three slightly different layered atomic structures, α, β, and sometimes γ. Lithium iridate exhibits metal-like, temperature-independent electrical conductivity, and changes its magnetic ordering from paramagnetic to antiferromagnetic upon cooling to 15 K.
Structure
Li2IrO3 typically crystallizes in the α or β phase, and a rare γ phase has been reported. The crystal structure of α-Li2IrO3 consists of an alternate stacking of hexagonal Li layers and honeycombs of edge-sharing IrO6 octahedra with Li in the center. The offset in adjacent layers results in a relatively low (monoclinic) crystal symmetry. Li2IrO3 crystals have abundant twinning defects where the ab crystal planes are rotated by 120° around the c axis.[1]
Synthesis


Li2IrO3 crystals can be grown by direct sintering of Ir and Li metals, which both oxidize during heating in ambient atmosphere. The α phase is formed at 750–1050 °C, while heating to higher temperatures results in the β phase. The use of Li metal instead of more traditional lithium carbonate, which is easier to handle and store, results in larger crystals. The γ phase can be obtained by the calcination of lithium carbonate and iridium(IV) oxide, followed by annealing in molten lithium hydroxide at 700–800 °C.[1]
Properties
Lithium iridate is black in color and has a relatively high, temperature-independent electrical conductivity characteristic of metals.[2] Its both α and β phases exhibit the Kitaev exchange coupling between magnetic spins originating from Ir4+ ions. These spins form an antiferromagnetic lattice at temperatures below 15 K (Néel temperature, TN), while the material is paramagnetic above TN.[1]
Potential applications
Lithium iridate is a potential electrode material for the lithium-ion battery.[2] This application is hindered by the high costs of Ir, as compared to the cheaper Li2MnO3 alternative.[3]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Freund, F.; Williams, S. C.; Johnson, R. D.; Coldea, R.; Gegenwart, P.; Jesche, A. (2016). "Single crystal growth from separated educts and its application to lithium transition-metal oxides". Scientific Reports 6: 35362. doi:10.1038/srep35362. PMID 27748402. Bibcode: 2016NatSR...635362F.
- ↑ 2.0 2.1 2.2 O'Malley, Matthew J.; Verweij, Henk; Woodward, Patrick M. (2008). "Structure and properties of ordered Li2IrO3 and Li2PtO3". Journal of Solid State Chemistry 181 (8): 1803. doi:10.1016/j.jssc.2008.04.005. Bibcode: 2008JSSCh.181.1803O.
- ↑ Yoshio, Masaki; Brodd, Ralph J.; Kozawa, Akiya (17 July 2010). Lithium-Ion Batteries: Science and Technologies. Springer Science & Business Media. p. 10. ISBN 978-0-387-34445-4. https://books.google.com/books?id=gkYhDYk6ftQC&pg=PA10.
![]() | Original source: https://en.wikipedia.org/wiki/Lithium iridate.
Read more |