Original Layered OP4-(Li,Na)CoO Phase: Insights on Its Structure, Electronic Structure, and Dynamics from Solid State NMR.

The OP4-(Li/Na)CoO phase is an unusual lamellar oxide with a 1:1 alternation between Li and Na interslab spaces. In order to probe the local structure, electronic structure, and dynamics, Li and Na magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy was performed in complementarity to X-ray diffraction and electronic and magnetic properties measurements. Li MAS NMR showed that NMR shifts result from two contributions: the Fermi contact and the Knight shifts due to the presence of both localized and delocalized electrons, which is really unusual.

Alkali-Glass Behavior in Honeycomb-Type Layered LiNaNiSbO Solid Solution.

Layered oxide compositions LiNaNiSbO have been prepared by solid-state synthesis. A complete solid solution is evidenced and characterized by X-ray and neutron diffraction as well as Li and Na solid-state nuclear magnetic resonance spectroscopy. The transition-metal layer is characterized by the classic honeycomb Ni/Sb ordering, whereas a more uncommon randomly mixed occupancy of lithium and sodium is evidenced within the alkali interslab space.

Oscillations in an array of bistable microelectrodes coupled through a globally conserved quantity.

The dynamical behavior of an array of microelectrodes is investigated under controlled current conditions during CO electrooxidation, a bistable electrochemical reaction with an S-shaped negative differential resistance (S-NDR) current-potential curve. Under these conditions, the total current constitutes a globally conserved quantity, thus coupling all microelectrodes globally. Upon increasing the total current, the microelectrodes activate one by one, with a single microelectrode being on its intermediate S-NDR current branch and the other ones being either on their passive or their active branches.