Abstract
The ZnCr&sub2;O&sub4;/ZnO materials system has a wide range of potential applications, for example, as a photocatalytic material for waste-water treatment and gas sensing. In this study, probe-corrected high-resolution scanning transmission electron microscopy and geometric phase analysis were utilized to study the dislocation structure and strain distribution at the interface between zinc oxide (ZnO) and embedded zinc chromium oxide (ZnCr&sub2;O&sub4;) particles. Ball-milled and dry-pressed ZnO and chromium oxide (α-Cr&sub2;O&sub3;) powder formed ZnCr&sub2;O&sub4; inclusions in ZnO with size ~400 nm, where the interface properties depended on the interface orientation. In particular, sharp interfaces were observed for ZnO [2113]/ZnCr&sub2;O&sub4; [110] orientations, while ZnO [1210]/ZnCr&sub2;O&sub4; [112] orientations revealed an interface over several atomic layers, with a high density of dislocations. Further, monochromated electron energy-loss spectroscopy was employed to map the optical band gap of ZnCr&sub2;O&sub4; nanoparticles in the ZnO matrix and their interface, where the average band gap of ZnCr&sub2;O4 nanoparticles was measured to be 3.84 ± 0.03 eV, in contrast to 3.22 ± 0.01 eV for the ZnO matrix.