Structural, Electrical, and Optical Properties of the Tetragonal, Fluorite-Related Zn0.456In1.084Ge0.460O3

Abstract

We report the discovery of Zn0.456In1.084Ge0.460O3, a material closely related to bixbyite. In contrast, however, the oxygen atoms in this new phase occupy 4 Wyckoff positions, which result in 4 four-coordinate, 24 six-coordinate (2 different Wyckoff positions), and 4 eight-coordinate sites as compared to the 32 six-coordinate (also 2 different Wyckoff positions) sites Of bixbyite. This highly ordered material is related to fluorite, Ag6GeSO8, and gamma-UO3 and is n-type with a bulk carrier concentration of 4.772 x 10(14) cm(-3). The reduced form n displays an average room temperature conductivity of 99(11) S-cm(-1) and an average optical band gap of 2.88(1) eV. These properties ate comparable to those of In2O3, which is the host material for the current leading transparent conducting oxides. The structure of Zn0.456In1.084Ge0.460O3 is solved from a combined refinement of synchrotron X-ray powder diffraction and time-of-flight neutron powder diffraction and confirmed with electron diffraction. The solution is a flew, layered, tetragonal structure in the I4(1)/amd space group with a = 7.033986(19) angstrom and c = 19.74961(8) angstrom. The complex cationic topological network adopted by Zn0.456In1.084Ge0.460O3 offers the potential for future studies to further understand carrier generation in 3 eV oxide semiconductors.