Mn-Promoted Growth of Mg-Based Spinel and Pyroxene Nanostructures

In this work, we demonstrate Mn-promoted growth of oxide nanostructures standing on a single-crystal MgAl₂O₄ substrate after heat treatment. Unlike the short truncated spinel pyramids under Au seeds, the addition of Mn produces spinel nanopillars with lengths of 100-300 nm and pyroxene nanowires up to 10 μm. Compared to Au seeds, Au/Mn seeds have different adsorption behavior and therefore provide an additional mass transfer path along seed surfaces that promotes the growth of nanostructures. This vaporization approach has a potential of being applicable to a wide range of complicated oxides.