Controlling self-assembled perovskite-spinel nanostructures

We report a discovery that self-assembled perovskite-spinel nanostructures can be controlled simply by selecting single-crystal substrates with different orientations. In a model BiFeO 3-CoFe 2O 4 system, a (001) substrate results in rectangular-shaped CoFe 2O 4 nanopillars in a BiFeO 3 matrix; in contrast, a (111) substrate leads to triangular-shaped BiFeO 3 nanopillars in a CoFe 2O 4 matrix, irrespective of the volume fraction of the two phases. This dramatic reversal is attributed to the surface energy anisotropy as an intrinsic property of a crystal. © 2006 American Chemical Society.