Heteroepitaxial growth and interface structure of pyrochlore (Ca,Ti)(2)(Nb,Ti)(2)O-7 thin films on (110) NdGaO3 substrates

Epitaxial thin films of (Ca, Ti)(2)(Nb, Ti)(2)O-7 with pyrochlore structure have been successfully fabricated on orthorhombic (1 1 0) NdGaO3 substrates by a magnetron sputtering system. By analysis of selected-area electron diffraction patterns, the film-substrate orientation relationship is determined to be < 0 0 1 >[1 0 0](film)//(0 0 1)(1 1 0)(substrate). Atomic-scale structure investigations of the heterointerface by means of advanced electron microscopy reveal that a perovskite-type Ca(Ti, Nb)O-3 layer with a thickness of several unit cells forms between the (Ca, Ti)(2)(Nb, Ti)(2)O-7 films and the NdGaO3 substrates. The formation of the Ca(Ti, Nb) O3 layer results from the demand for accommodation of the crystal structure mismatching between the pyrochlore film and the perovskite-type substrate, which favors the epitaxial growth of the (Ca, Ti)(2)(Nb, Ti)(2)O-7 films on the NdGaO3 substrates. (C) 2017 Elsevier B.V. All rights reserved.