Microwave-Hydrothermal Synthesis of Nanostructured Zinc-Copper Gallates

Zinc gallate is an important semiconductor for manifold applications, e.g. in field emission displays or as a photocatalyst for water splitting. In addition to these interesting properties, zinc gallate is also an excellent matrix material that can be furthermore tuned through the incorporation of guest cations to form functional solid solutions with new optical and catalytic properties. We present a convenient microwave-hydrothermal synthesis of nanostructured Cu2+-substituted ZnGa2O4 spinels and their characterization with respect to morphology, chemical composition, structural, magnetic and optical properties. The microwave-based approach offers a straightforward and one-step access to nanostructured zinc gallate-based materials and related compounds as a new preparative advantage. As the properties of mixed spinel-based solid solutions strongly depend on the distribution of the guest ions between the different lattice sites, we have employed a wide range of analytical techniques to investigate the physico-chemical properties of the obtained copper-containing zinc gallate materials. The element specific EX-AFS analysis at the Cu K- and Zn K-edge shows a difference in the coordination environments with Zn mostly situated on the tetrahedral sites of the spinel lattice whereas Cu is located on the octahedral sites of the nanostructured ZnGa2O4:Cu2+ materials.