posted on 2014-06-05, 00:00authored byMatthea
A. Peck, Marjorie A. Langell
The metal structural environments
in macroscale and nanoscale ZnxNi1–xO
solid solutions were examined using X-ray diffraction (XRD), X-ray
absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy
(XPS). XRD demonstrates that solid solutions form for both macroscale
(bulk) and nanoscale crystallites, and that the lattice parameter
increases linearly as the amount of zinc increases, an indication
of a homogeneous solid solution. XAS for both the bulk material and
the nanoparticles reveals that the zinc atoms are incorporated into
the rocksalt lattice and do not form zinc oxide clusters. The X-ray
absorption near edge spectroscopy (XANES) of the Zn k-edge region in the solid solution is similar to the Ni k-edge region of NiO, and not the Zn k-edge region
of ZnO. XPS confirms that solid solutions are formed; Auger parameters
for zinc are consistent with a different geometry than the tetrahedral
coordination of wurtzite ZnO. Nanoscaled solid solutions show evidence
of a lattice contraction relative to macroscale solutions of the same
concentration. While the contraction persists across the entire concentration
range, the nanoparticle lattice parameter approaches the bulk ZnxNi1–xO
value as the concentration of zinc increases to predict ZnO rocksalt
lattice parameters that are in agreement with observed ZnO data.