Iron-stabilized nanocrystalline ZrO2 solid solutions: Synthesis by combustion and thermal stability

Abstract

The synthesis of Fe3+-stabilized zirconia by the nitrate/urea combustion route was investigated. Using several characterization techniques, including X-ray diffraction, field-emission-gun scanning electron microscopy and notably Mo¨ ssbauer spectroscopy, it was possible to determine the appropriate amount of urea that allows to obtain a totally stabilized Zr0.9Fe0.1O1.95 solid solution. The nanocrystalline zirconia solid solution is mostly tetragonal, but the presence of the cubic phase could not be ruled out. An indepth study of the thermal stability in air showed that the Fe3+ solubility in the stabilized solid solution starts to decrease at about 875 8C which results in the formation of hematite (possibly containing some Zr4+) at the surface of the zirconia grains and further provokes the progressive transformation into the monoclinic zirconia phase.