Spatial Control of Crystallographic Direction in 2D Microarrays of Anisotropic Nanoblocks on Trenched Substrates.

Elaborate two-dimensional (2D) microarrays of tetragonal Mn3O4 nanocuboids 10-20 nm in size were constructed with parallel trenches 500 nm wide and 500 nm deep on a silicon substrate. By adjusting the conditions, including the dispersion medium, particle concentration, and evaporation rate, the a-face and c-face 2D arrays were selectively deposited on the upper and lower stages of the trenches, respectively. The crystallographic direction of the tetragonal crystal was alternately switched in the 2D microarrays under these specific conditions at the optimal particle concentration and evaporation rate. Spatial switching of their crystallographic direction was achieved via interaction of the anisotropic nanoblocks and the specifically shaped surfaces.