Physics of electrochromism: An advanced laboratory experiment

Amorphous tungsten trioxide films offer an interesting electrochromic system whose properties are readily amenable to study in a senior undergraduate laboratory. Basic optical color center properties, and electron and proton diffusion processes are characterized for the H/sub x/WO3 produced; additional experiments including the variation of the chemical potential of the hydrogen component and low-temperature exploration of the metal-insulator transition are proposed for the advanced student. The samples are easily prepared and measured by elementary means. The broad solid-state concepts involved enrich standard advanced laboratory repertoires of more conventional nuclear and NMR experiments