Interleaved oxovanadium cations in the rancieite manganese oxide delta-MnO2

A mixed vanadium manganese oxide was synthesized through a chimie douce rou te. The synthesis proceeds via a cationic exchange reaction occurring betwe en the layers of a synthetic rancieite, a lamellar manganic acid. The vanad ium atoms were found to be at a distance from Mn close to the Mn-Zn distanc e in chalcophanite, a model for the phyllomanganates. XAS refinements did n ot reveal the presence of manganese atoms between the layers of either the protonic or Li-exchanged forms of the rancieite. Li insertion is largely im peded by the presence of dioxovanadium cations, which seem to be accommodat ed into one of the Li potential sites present in the Li-exchanged phase.