Effect of isothermal annealing on formation of self-assembled nanostructures in manganese spinel ZnMnGaO4.

The effects of isothermal annealing on the self-assembled nanostructures of spinel manganese oxide ZnMnGaO₄ were investigated using transmission electron microscopy and x-ray diffraction. The checkerboard nanostructures and zigzag nanostructures (named "Sierra" nanostructures) coexisted owing to the chemical phase separation of Mn³⁺ and Ga³⁺ ions by isothermal annealing at 575 °C. It was observed that the checkerboard nanostructures were dominant in short-time annealing and that the volume fraction of the Sierra nanostructures became more prominent as the annealing period increase. The interdiffusion of Mn³⁺ and Ga³⁺ is indicated to play an important role in gaining the total energy of the system by the reduction in the local strain caused by the formation of nanostructures. These results provide further insights into the fabrication of distinct types of nanostructures in complex transition-metal compounds. [ABSTRACT FROM AUTHOR]