Nickel oxide films with the zinc blende-type structure – A re-evaluation of X-ray diffraction data

The previously unobserved formation of zinc blende-type structured nickel oxide films (NiO 1.2 ) was discovered by the re-evaluation of X-ray powder diffraction data. Nickel oxide films were synthesized by deposition of nickel together with activated oxygen at substrate temperatures of 83 K and 298 K. At 83 K, amorphous NiO films are formed, which crystallize at around 473 K forming the rock salt-type structure. In contrast, films deposited at 298 K are polycrystalline and form the zinc blende-type structure. Both structures have largely identical lattice parameters with the same nickel fcc sublattice, but with either tetrahedral or octahedral sites filled with oxygen atoms. The only difference observed between the X-ray powder patterns is the intensity of the reflections. The calculation of X-ray difference maps was decisive in distinguishing between the two structures. The Ni-O distances in the zinc blende structure are 181 pm, confirming the presence of Ni III in the NiO 1.2 film.