Phase formation and lattice distortion of Lu2O3-doped ZrO2 in comparison with Y2O3-doped ZrO2

Lu2O3 and Y2O3 doping of 8, 11, and 18 mol% in ZrO2 were prepared by solid solution reaction, aiming to study the phase stabilization of Lu2O3-doped ZrO2 and Y2O3-doped ZrO2 in terms of phase formation and lattice distortion. The Rietveld refinement results indicated that Lu2O3-doped ZrO2 and Y2O3-doped ZrO2 followed the same trend in terms of cubic phase fraction, increasing from 25%-30% (8 mol%) to 95%-100% (11 and 18 mol%). This phase formation was confirmed by observing the same diffraction ring pattern observed for the Lu2O3-doped ZrO2 and Y2O3-doped ZrO2. The Vickers hardness of the Lu2O3-doped ZrO2 was 4.3% higher than that of Y2O3-doped ZrO2 at 8 mol%, but 9.7% and 14.8% lower at 11 and 18 mol%, respectively. This was likely caused by the lattice distortion effect of Y2O3 doping overpowering the field strength difference between Lu3+ and Y3+.