Synthesis and characterization of h-MgxWO3 and MgxW18O49 and their intercalation with lithium

New tungsten bronzes, MgxWO3 and MgxW18O49, have been synthetized by magnesium chemical insertion reaction. For the former case, two blue bronzes with composition Mg0.09WO3 and Mg0.15WO3 have been isolated through a topotactic reaction that keeps the parent hexagonal structure unaltered. In the case of W18O49, a new compound with composition Mg0.9W18O49 and lattice parameters close to those of W18O49 has been synthetized. We have also studied the electrochemical lithium insertion in h-MgxWO3 and MgxW18O49. In this way, different phases have been detected in the systems Li-MgxWO3 and Li-MgxW18O49 and a relationship between the maximum quantity of lithium inserted and the magnesium content is deduced and discussed in terms of the ionic potential of the intercalated ions.