Zinc nickel oxide forms a rocksalt solid solution ZnxNi1-xO up to a concentration of approximately x =0.3, placing Zn2+ into the cation sites of the stable NiO rocksalt lattice.  X-ray diffraction (XRD) indicates that the solid solution follows Vegard's law, implying an ideal solution with random substitution of Zn2+ into octahedrally coordinated Ni2+ sites even though Zn2+ prefers tetrahedral coordination.  The local environment of the zinc cation in the solid solution is not easily measured by long-range diffraction techniques.  Utilizing X-ray absorption fine structure (XAFS) multiple-scattering analysis of the metal K edge, Zn2+ and Ni2+ are shown to be structurally equivalent, with a local octahedral environment, and also display the characteristic expansion of the metal-oxygen bond with increasing x that is expected for an ideal solid solution.  The X-ray absorption near edge structure (XANES) regions for Ni2+ and Zn2+ are very similar, but both the Zn2+ edge energy and the XANES spectrum are markedly different from wurtzite ZnO.  The local Zn2+ environment is undistorted from octahedral coordination and is comparable to that of the Ni2+ cation.  The ZnxNi1-xO solid solutions are therefore demonstrated to be ideal in both long-range and local order.

Metal structural environment in Zn<sub>x</sub>Ni<sub>1-x</sub>O solid solutions by XAFS

246th National Meeting (2013)

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Metal structural environment in ZnxNi1-xO solid solutions by XAFS

Metal structural environment in Zn_xNi_1-xO solid solutions by XAFS