Epitaxial growth mechanism of La ₂Zr ₂O ₇ thin film on metal substrate

We have studied the growth behavior of pyrochlore structure La ₂Zr ₂O ₇ (LZO) thin films with different thickness on biaxial texture NiW substrates prepared by metal-organic deposition (MOD) method. The structure and morphology of LZO films were investigated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Our results show that the surface morphology of LZO films varies with changes in the surface coverage ratio of the metal substrates after crystallization in argon-hydrogen atmosphere. The degree of texture of the LZO films reaches a maximum when the film thickness increases to 37 nm, where the NiW substrate surface is just fully covered. The complete coverage of the substrate surface together with the enhanced texture suggests that there exists a possible connection between the surface morphology and the texture development of the films prepared by MOD. Information on the nucleation and growth of oxide thin films on metal substrates with biaxial texture is important for understanding the mechanism of buffer layer formation and also for optimizing the preparation conditions for high-temperature superconducting coated conductors.