Specific heat measurements on Na 0.5 CoO 2 show that the transitions observed at 87 and 53 K in the resistivity and magnetic susceptibility are accompanied by changes in entropy, whereas the one near 20 K is not. Electron diffraction studies suggest that the 87 K transition has a structural component. The crystal structure of Na 0.5 CoO 2 , determined by powder neutron diffraction, consists of layers of edge-shared CoO 6 octahedra in a triangular lattice, with Na ions occupying ordered positions in the interleaving planes. The Na ions form one-dimensional zigzag chains. Two types of Co ions are also found in chains.
No takes yet. Share an insight, caveat, or question.
Huang et al. (2004) studied this question.
Synapse has enriched one closely related paper. Consider it for comparative context: