Phase relationships and physical properties of homologous compounds in the zinc oxide-indium oxide system

Equilibrium phase relationships in the ZnO-In₂O₃ system were determined between 1100° and 140O°C using solidstate reaction techniques and X-ray diffractometry. In addition to ZnO and In₂O₃, nine homologous compounds, Zn_kIn₂O_k+₃ (where k = 3, 4, 5, 6, 7, 9, 11, 13, and 15), were observed. Electrical conductivity and diffuse reflectance of the k = 3, 4, 5, 7 and 11 members were measured before and after annealing at 40O°C for 1 h under forming gas (4% H₂-96% N₂). Room-temperature conductivity increased as k decreased, because of increased carrier concentration as well as increased mobility. In general, transparency in the wavelength range of 450-900 nm increased as k increased. Reduction in forming gas resulted in increased conductivity and reduced transparency for all compounds measured. The highest room-temperature conductivity measured, 270 S/cm, was that of reduced Zn₃In₂O₆.