Tungsten trioxide powder for electrochromic device is an electrochromic metal oxide. Experts say that almost all electrochromic oxides have a BO6 configuration. The figure below shows a unit cell of ABO3 perovskite lattice structure.
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From the figure, we can see that the B ion occupies the top of the cube, the O atom bisects the edge, and the central atom A can be ignored here. It is vacant in almost all electrochromic oxides, and the corresponding (defective) perovskite structure is often referred to as the "ReO3" structure. Obviously, this structure can be seen as a continuous framework formed by a myriad of octahedrons sharing a corner oxygen atom. There are a wide range of channels. The octahedron can be regular or deformed. The way octahedrons are connected is related to the stoichiometry of their skeleton, which can be co-angled, co-edge or coplanar. But even if the stoichiometry is the same, different metal oxides are connected in different ways. The filling of the central cation reduces the average oxidation state of B, thereby forming a mixed oxide with high electronic conductance and varying degrees of ionic conductance. Films of electrochromic oxides rarely exhibit long-range order and can be thought of as "microcrystals" rather than true "amorphous".
