Investigation of the growth and stability of (1 0 0)[0 0 1] NiO films grown by thermal oxidation of textured (1 0 0)[0 0 1] Ni tapes for coated conductor applications during oxygen exposure from 700 to 1400 °C

Abstract

Thin (<1 μm) transparent epitaxial NiO films were grown on oxide-free (1 0 0)[1 0 0] Ni tapes by thermal oxidation at about 1250 °C in air. The growth of this oxide layer successfully suppressed the secondary recrystallization of pure Ni tapes, normally observed at these temperatures. A dense NiO <1 0 0> nucleation rather than competitive grain growth controls the texture in this case. Nevertheless, the removal of the native oxide layer is crucial. Further oxidation of these templates in the temperature range from 800 to 1400 °C produced single crystal-like NiO films with a thickness up to ~70 μm and an improved cube texture. Comparison with the literature data indicates that volume diffusion of Ni contributes predominantly to the NiO growth over the whole temperature range. These NiO films can act as a good oxidation barrier at lower temperatures (~800 °C) for coated conductor applications.