Evidence for Tetrahedral Zinc in Amorphous In2–2xZnxSnxO3 (a‐ZITO)

The structure of amorphous In2-2xZnxSnxO3 (a-ZITO, x = 0.2, 0.3, 0.4) was investigated with transmission electron microscopy (TEM), the total scattering pair-distribution function (PDF) and X-ray absorption spectroscopy (XAS), which revealed a well-defined short-range structure that differed from the crystalline bixbyite and corundum ZITO polymorphs. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were used to detect InO6 and SnO6 octahedra and ZnO4 tetrahedra in a-ZITO, which differ from the InO6, SnO6 and ZnO6 pseudo-octahedra that are observed in the bixbyite and corundum ZITO polymorphs. The formation of the ZnO4 tetrahedron likely inhibits the crystallization of ZITO when synthesized under mild conditions. in situ XRD showed a gradual transition from a-ZITO to a mixture of the bixbyite and corundum ZITO polymorphs as the temperature was raised from 300 degrees C to 568 degrees C.