Hyperfine Study on Sol-Gel Derived-Hematite Doped Zirconia

The nature and thermal evolution of nanoconfigurations around cations in a sol-gel derived solid solution of a ZrO2 15 mol % Fe2O3 nominal concentration have been investigated by means of the hyperfine techniques of the Mössbauer effect at the Fe sites and perturbed angular correlation spectroscopy (PAC) at the Zr sites, assisted by X-ray diffractometry and thermal analyses. The resulting substitutional solid solution is metastable tetragonal zirconia and exhibits a solubility of 12 mol % of Fe2O3 up to temperatures near 750 °C. The hyperfine experiments allowed the establishment of the existence of two nonequivalent sites for each of the probe cations. The most disordered one reflects the influence of the oxygen vacancy introduced after Fe3+ substitution for Zr4+, which is shared by host and dopant cations. The other tetragonal nanoconfiguration, characterized by PAC for the first time, has been thought to involve a direct interaction between the nearest Fe and Zr ions of the largely distorted cation network.