Effect of annealing on the valence state of Ce ions and electrical properties in (ZrO2)0·88(CeO2)0.12 and (ZrO2)0.89(Sc2O3)0·1(CeO2)0.01

• Published in: Results in materials 2023-06, Vol.18, p.100395, Article 100395
• Main Author: Nakayama, Susumu
• Format: Article
• Language: English
• Subjects: Complex plane impedance analysis; Nyquist plot; Scanning electron microscope; X-ray diffraction; X-ray photoelectron spectroscopy
• ISSN: 2590-048X; 2590-048X
• DOI: 10.1016/j.rinma.2023.100395

For (ZrO2)0·88(CeO2)0.12 (CEZ-12) and (ZrO2)0.89(Sc2O3)0·1(CeO2)0.01 (10Sc1CeSZ) sintered at 1450 °C, the effect of annealing at 600 °C in air for 500, 1000, and 2000 h on the valence state of Ce and the material electrical properties was investigated. For CEZ-12 and 10Sc1CeSZ, the XRD patterns showed no CeO2 peak before and after annealing. Further, the SEM images of the surfaces before and after annealing showed no change in the crystal grain size. No change in the apparent densities was observed either. On the other hand, XPS revealed that most of the Ce was trivalent before annealing, with some tetravalent Ce forming following annealing. The bulk resistivity, grain-boundary resistivity, and electrode interface resistivity were not significantly affected by annealing and the difference in annealing time. •Before and after annealing, the XRD patterns, crystal grain sizes (observed by SEM), and apparent densities of (ZrO2)0·88(CeO2)0.12 and (ZrO2)0.89(Sc2O3)0·1(CeO2)0.01 showed no apparent change.•XPS analysis of (ZrO2)0·88(CeO2)0.12 and (ZrO2)0.89(Sc2O3)0·1(CeO2)0.01revealed that most of the Ce was trivalent before annealing, and some of the Ce changed to a tetravalent state after annealing.•The bulk, grain-boundary, and electrode interface resistivities in (ZrO2)0·88(CeO2)0.12 and (ZrO2)0.89(Sc2O3)0·1(CeO2)0.01 ceramics were not significantly changed by annealing for various annealing times.