Combinatorial substrate epitaxy: A high-throughput method for determining phase and orientation relationships and its application to BiFeO 3 /TiO 2 heterostructures

Abstract A new technique, combinatorial substrate epitaxy, has been used to study the polymorphic stability and orientation relationships (ORs) for TiO 2 thin films grown by pulsed laser deposition on polycrystalline BiFeO 3 at 600°C. Electron backscatter diffraction data from 150 substrate/film pairs were analyzed to determine that anatase (A) grew with the OR (1 1 2) A || (1 1 1) BFO and ½1 1 0 A jj ½1 1 0 BFO on BiFeO 3 (BFO) substrates oriented within 35°of [1 0 0]. Rutile (R) was found on all other substrate orientations with (1 0 0) R || (1 1 1) BFO . The in-plane orientation was primarily [0 0 1] R || ½1 1 0 BFO , but some films near the anatase/rutile phase boundary were rotated by 30°so that [0 0 1] R || ½ 1 2 1 BFO . Because these substrate film pairs have high-index interface planes, conventional epitaxy arguments based on two-dimensional lattice mismatch in low-index planes are considered to be limiting cases of a more general model involving the three-dimensional alignment of closest packed planes and directions, regardless of the interface plane