Stacking faults and metallic properties of triangular lattice CoO2 with a three-layer structure
Abstract
A triangular lattice system CoO2 is synthesized through chemical extraction of Li from LiCoO2 with H2SO4. On the basis of the x-ray powder diffraction and various composition analyses, the structure approximately modelled with space group R\overline {3}m and cell dimensions a = 2.8388(6) and c = 13.439(1) Å in the hexagonal basis has three oxygen layers with a prismatic oxygen environment (P3) between the layers. It also has stacking faults with shift vectors \bi {s}_{1}=\frac
{2}{3}\bi {a}+\frac {1}{3}\bi {b} and \bi {s}_{2}=\frac {1}{3}\bi {a}+\frac {2}{3}\bi {b} along the shift of \frac {1}{3}\bi {c} . Through measurements of the thermoelectric power and magnetic susceptibility, CoO2 (P3) is suggested to be a weakly correlated metal with a mass enhancement of 2.6. Na0.09CoO2 synthesized through Na extraction from Na0.7CoO2 also shows metallic properties with correlation effects probably stronger than those of CoO2 (P3).- Publication:
-
Journal of Physics Condensed Matter
- Pub Date:
- April 2008
- DOI:
- 10.1088/0953-8984/20/17/175207
- Bibcode:
- 2008JPCM...20q5207O