A 1D periodic structure of ferroelectric domains in epitaxial BiFeO3 films is created. By careful control of the growth mechanism for the SrRuO3 bottom electrode, its in-plane lattice parameters are confined by the underlying DYSCo3 (110)(O) single-crystal substrate, enabling the formation of an expitaxial film of (110)(O) SrRuO3 with a single structural domain (see figure).