EXAFS study of mixed nickel molybdenum oxide thin films at the Ni and Mo K-edges

摘要

Mixed nickel molybdenum oxide thin films were produced by DC magnetron co-sputtering technique with the nickel content about 8, 16 and 25 at%. X-ray absorption spectroscopy at the Ni and Mo K-edges was used to study the local atomic structure in the films. The best-fit analysis of the EXAFS signals suggests that (ⅰ) the films are amorphous, except for the highest nickel content (25 at%), at which a segregation of NiO phase was observed; (ⅱ) nickel and molybdenum atoms are octahedrally coordinated by oxygen atoms. Opposite to the NiO_6 octahedra, the MoO_6 octahedra are strongly distorted, that results in an existence of two groups of oxygen atoms — four nearest at ～ 1.76 A and two distant at ～ 2.2 A. It was also found that the MoO_6 octahedra are joined by edges, with the Mo-Mo distance about 3.26-3.31 A.