Quantum and/or thermal melting of a polaron Wigner crystal

We study the properties of a lattice of large polarons at low density, whic h crystallize due to the long-range Coulomb repulsion. We analyze the insul ator-to-metal transition occurring in the system as the density or the temp erature increase, and propose a new transition mechanism based on polaron d issociation. Finally, an optical signature for such a mechanism is provided in the limit of strong electron-phonon coupling.