Effect of iron impurity on structural development in ball-milled ZrO2–3 mol% Y2O3

Powders Mixture of monoclinic ZrO2 and 3 mol% Y2O3 were prepared by high-energy ball milling. Ball-milled products were investigated by means of X-ray diffraction, Rietveld refinement, spectrophotometry and Mössbauer spectroscopy. The tetragonal Zr1–xYxO1.982 (x=0.037) was formed within 30 min of ball milling in which the crystallite size decreases up to 13 nm and appears almost unchanged even after 30 h of milling. Peak intensities of the monoclinic phase decrease and disappear after 10 h of milling. The unit cell-volume of tetragonal phase decreases with increasing iron content incorporated from milling media. In the calcined product ball-milled for 30 h the monoclinic phase takes place in the range 700–900 °C and disappears at 1100 °C due to the presence of Y3+ cations. It was concluded that at room temperature, the stabilization of tetragonal phase at the beginning of milling process was attributed to the substitutional Fe3+ cations, while the hematite Fe2O3 was formed at the end of ball milling.