The Chemical Instability of Na2IrO3 in Air

Abstract

We report that Na2IrO3, which has a layered honeycomb iridium oxide sublattice interleaved by Na planes, decomposes in laboratory air while maintaining the same basic crystal structure. The decomposition reaction was monitored by time-dependent powder x-ray diffraction under different ambient atmospheres, through which it was determined that it occurs only in the simultaneous presence of both CO2 and H2O. A hydrated sodium carbonate is the primary decomposition product along with altered Na2IrO3. The diffraction signature of the altered Na2IrO3 is quite similar to that of the pristine material, which makes the detection of decomposition difficult in a sample handled under ordinary laboratory conditions. The decomposed samples show a significantly decreased magnetic susceptibility and the disappearance of the low temperature antiferromagnetic transition considered to be characteristic of the phase. Samples that have never been exposed to air after synthesis display a previously unreported magnetic transition at 5K.

Submitted to Materials Research Bulletin, 22 double spaced pages, 3 tables, 5 figures

References in corpus (4)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Quantum spin Hall effect in a transition metal oxide Na2IrO3
• Crystal Structure and Elementary Properties of NaxCoO2 (x = 0.32, 0.5, 0.6, 0.75, and 0.92) in the Three-Layer NaCoO2 Family

Cited by in corpus (11)

• Models and Materials for Generalized Kitaev Magnetism
• Short-range correlations in the magnetic ground state of Na4Ir3O8
• New Honeycomb Iridium (V) Oxides: NaIrO${}_3$ and Sr${}_3$CaIr${}_2$O${}_9$
• High-pressure versus isoelectronic doping effect on the honeycomb iridate Na${}_2$IrO${}_3$
• Chemical- and hydrostatic-pressure effects on the Kitaev honeycomb material Na${}_2$IrO${}_3$
• Spin orientations of the spin-half Ir4+ ions in Sr3NiIrO6, Sr2IrO4 and Na2IrO3: Density functional, perturbation theory and Madelung potential analyses
• Evolution of Magnetism in the $N{a}_{3-d}N{a}_{1-x}M{g}_{x}I{r}_2{O}_6$ Series of Honeycomb Iridates
• High-temperature magnetic anomaly via suppression of antisite disorder through synthesis route modification in a Kitaev candidate Cu${}_2$IrO${}_3$
• Conductivity of Dirac-like surface states in correlated honeycomb transition metal oxide Mott insulators
• Dynamic Surface Modification due to Effusion of Na in Na${}_2$IrO${}_3$
• Metallic conductivity on Na-deficient structural domain walls in the spin-orbit Mott insulator Na${}_2$IrO${}_3$