Lu 2 O 3 and Y 2 O 3 doping of 8, 11, and 18 mol% in ZrO 2 were prepared by solid solution reaction, aiming to study the phase stabilization of Lu 2 O 3 -doped ZrO 2 and Y 2 O 3 -doped ZrO 2 in terms of phase formation and lattice distortion. The Rietveld refinement results indicated that Lu 2 O 3 -doped ZrO 2 and Y 2 O 3 -doped ZrO 2 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 Lu 2 O 3 -doped ZrO 2 and Y 2 O 3doped ZrO 2 . The Vickers hardness of the Lu 2 O 3 -doped ZrO 2 was 4.3% higher than that of Y 2 O 3 -doped ZrO 2 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 Y 2 O 3 doping overpowering the field strength difference between Lu 3+ and Y 3+ .
K E Y W O R D Scomparable tripositive ion, crystal structure, Lu 2 O 3 -doped ZrO 2 , nanoindentation, phase formation
The degradation behavior of yttria-stabilized zirconia by thermal aging was investigated in terms of phase transformation, local atomic structure, and electrical conductivity. The average grain size of 8YSZ was increased from 20.83 μm to 25.81 μm with increasing aging temperature. All 8YSZ samples degraded at different temperatures had a predominantly cubic structure. The (400) peak of 8YSZ deteriorated at 1300 and 1400 °C shifted to a high angle, and the peak of tetragonal was not indexed. For 8YSZ degraded at 1500 °C, the (400) peak shifted to a lower angle, and the peak of tetragonal was identified. Analysis of the local microstructure of aged 8YSZ using extended X-ray absorption fine structure showed that the intensity of the Zr-O peak gradually increased and that the intensity of the peak of cationic Zr decreased as the aging temperature increased. The changes in the peaks indicate that the oxygen vacancies were reduced and Y3+ ions escaped from the lattice, leading to the destabilization of 8YSZ. The activation energies of 8YSZ at 1300 °C and 1400 °C were derived to be 0.86 and 0.87 eV, respectively, and the activation energy of 8YSZ at 1500 °C increased significantly to 0.92 eV. With the thermal deterioration of 8YSZ, the cation (Y3+) escaped from the lattice and the number of oxygen vacancies decreased, resulting in the formation of a tetragonal structure and high activation energy at 1500 °C.
The degradation behavior of yttria-stabilized zirconia under thermal stress was investigated in terms of phase transformation, local atomic structure, and electrical conductivity. The average grain size of 8YSZ were increased from 20.83 µm to 25.81 µm with increasing aging temperature. All 8YSZ samples degraded at different temperatures had a predominantly cubic structure. The (400) peak of 8YSZ deteriorated at 1300 and 1400°C shifted to high angle, and the peak of tetragonal was not indexed. For 8YSZ degraded at 1500°C, the (400) peak shifted to a lower angle, and the peak of tetragonal was identified. In the local atomic structure of the aged 8YSZ with extended X-ray absorption fine structure, the intensity of the Zr-O peak gradually increased, and the intensity of the Zr-Cation peak decreased as the aging temperature increased. The changes in the peaks indicate that the oxygen vacancies were reduced and Y3+ ions escaped from the lattice, leading to destabilization of 8YSZ. The activation energies of 8YSZ at 1300°C and 1400°C were derived to be 0.86 and 0.87 eV, respectively, and the activation energy of 8YSZ at 1500°C increased significantly to 0.92 eV. With the thermal deterioration of 8YSZ, the cation (Y3+) escaped from the lattice and the number of oxygen vacancies decrease, resulting in the formation of a tetragonal structure and high activation energy at 1500°C.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.