Quantum mechanical investigations on the insertion compounds of early transition metal oxides

We present the results of electronic structure ab initio Hartree-Fock calcu lations performed on the perovskite, hexagonal, pyrochlore and layered poly morphic structures of MoO3 and WO3. We also examine their sodium and potass ium insertion compounds, i.e. the molybdenum and tungsten bronzes; the mate rials examined are at the basis of applications in electrochromic devices a nd rechargeable batteries. Results of the calculations allow to gain insigh t into the processes occurring at the atomic level during the insertion pro cess: we examine the relative stability of the host MoO3 and WO3 frameworks under addition of electrons to the conduction band, and extraframework ion s in the empty interstices of the host lattice, which occur upon electroche mical insertion. The extraframework ions show a templating behaviour for th e structure of the host transition metal oxide framework, reminiscent of ze olite synthesis. We exploit the knowledge gained in the latter field of res earch to examine the feasibility of the synthesis of novel microporous tran sition metal oxide lattices with composition MoO3 and WO3.