Physical Sciences and Mathematics Commons^™

Electronic Texture Of The Thermoelectric Oxide Na0.75coo2, M -H Julien, C De Vaulx, H Mayaffre, C Berthier, M Horvatic, V Simonet, J Wooldridge, G Balakrishnan, M R. Lees, Dapeng Chen, C T. Lin, P Lejay

Australian Institute for Innovative Materials - Papers

From 59Co and 23Na NMR, we demonstrate the impact of the Na+ vacancy ordering on the cobalt electronic states in Na0.75CoO2: at long time scales, there is neither a disproportionation into 75 % Co3+ and 25 % Co4+ states, nor a mixed-valence metal with a uniform Co3.25+ state. Instead, the system adopts an intermediate configuration in which 30 % of the lattice sites form an ordered pattern of localized Co3+ states. Above 180 K, an anomalous mobility of specific Na+ sites is found to coexist with this electronic texture, suggesting that the formation of the latter may contribute to stabilizing …