A transmission electron microscopy study of orientation relationships and interfacial reaction products in GdFe0.5Cr0.5O3 films grown on (001) SrTiO3 substrates by solution synthesis

GdFe₀.₅Cr₀.₅O₃ (GFCO) is a single-phase magnetoelectric multiferroic at temperatures close to ambient. Epitaxial thin films of this orthorhombic perovskite would offer the possibility of tuning its electrical and magnetic properties through control of strain and interface effects. Here, 200 nm thick GFCO thin films have been grown on (001) SrTiO₃ substrates by solution synthesis and the microstructures have been investigated by cross-sectional transmission electron microscopy. The GFCO films are epitaxial but exhibit a mixture of three different orientation relationships in the form of domains ≈50 nm in diameter. Geometric analyses of the lattice matching show that the misfits for these domains would be tensile with magnitudes of less than 2 %. Pockets of a SrCrO₄ reaction product form at the film/substrate interface and do not exhibit any simple orientation with the adjacent phases. The product morphology indicates that the outward diffusion of Sr is more rapid than the inward diffusion of Cr, and this is related to the microstructures of the surrounding phases. These data show that epitaxial films of GFCO can be obtained via this route, but careful control of process parameters would be required to produce single-domain films, and alternate substrates or buffer layers would be needed to inhibit SrCrO₄ formation.