Growth and characterization of pyrochlore-type (Ca,Ti)2(Nb,Ti)2O7 thin films

Abstract Pyrochlore-type (Ca,Ti)2(Nb,Ti)2O7 thin films have been grown on single-crystalline LaAlO3 and yttria-stabilized zirconia substrates by a magnetron sputtering system. Atomic-scale interface structure and growth mode of the (Ca,Ti)2(Nb,Ti)2O7 films on the substrates with different crystal structures have been investigated by advanced electron microscopy techniques. In both heterosystems, the film/substrate orientation relationship of [100](001)film//[100](001)substrate has been determined. In the heterosystem of (Ca,Ti)2(Nb,Ti)2O7/yttria-stabilized zirconia, the films directly grow on the substrates. In contrast, in the (Ca,Ti)2(Nb,Ti)2O7/LaAlO3 heterosystem, a perovskite-type Ca1-□(Ti,Nb)O3 interlayer with a few unit cells in thickness forms at the interface and interfacial reconstruction occurs at the (Ca,Ti)2(Nb,Ti)2O7/Ca1-□(Ti,Nb)O3 interface. Our findings indicate that the formation of the interlayer and the (Ca,Ti)2(Nb,Ti)2O7/Ca1-□(Ti,Nb)O3 interface reconstruction can accommodate the film/substrate dissimilarities in the crystal structures and facilitate the growth of single-crystalline pyrochlore-type films on the perovskite-type substrates.