Structure and composition of sputter-deposited nickel-tungsten oxide films

Films of mixed nickel-tungsten oxide, denoted Ni x W 1− x oxide, were prepared by reactive DC magnetron co-sputtering from metallic targets and were characterized by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x < 0.50 the films comprised a mixture of amorphous WO 3 and nanosized NiWO 4, at x = 0.50 the nanosized NiWO 4 phase was dominating, and at x > 0.50 the films contained nanosized NiO and NiWO 4.