Electrochemical zinc insertion into W18O49: Synthesis and characterization of new bronzes

Divalent zinc ions have been electrochemically inserted into W18O49, producing zinc bronzes. Under our experimental conditions, W18O49 accepts zinc reversibly as a guest up to 0.9 ions per formula. The reaction seems to proceed through the formation of a solid solution in which the W–O framework of the parent oxide is maintained. The location of the Zn2+ ions in the framework of W18O49 has been determined by neutron diffraction on a chemically prepared sample having the composition Zn0.34W18O49. As a main result, we found that Zn prefers to insert in one of the four types of quadrangular tunnels. More precisely, it is displaced from the center to occupy a low coordination site. This result indicates that a significant covalent character exists in the Zn–O bond.