Resumen: The redox behavior of terbium and praseodymium doped yttria-stabilized zirconia (YSZ) is studied. The aim is to identify spectroscopic probes and a suitable experimental procedure to monitor the oxygen activity in YSZ electrolytes in solid oxide cells with spatial resolution and at operation conditions (e.g. at high temperatures). Sintered ceramics and crystals with 0.3 to 10 at% content of Pr or Tb ions in YSZ were prepared. Upon equilibration in atmospheres from 10-20to 100 bar PO2around 800 °C, the majority of these rare earth ions are in the 3 + oxidation state. At oxygen pressures above 0.001 bar, the small proportion of Tb4+and Pr4+formed give rise to intense optical absorption around 300 500 nm and to decreased reflectance. From the reflectance measurements it is shown that the Tb4+concentration increases as PO21/4, as correspond to the trapping of the holes generated upon the oxygen incorporation as Tb4+. This competitive absorption causes a decrease of the Tb3+luminescence. A quantitative relationship of the Tb3+luminescence intensity with PO2at 800 °C has been found, which is compatible with the trapping model. The spatial resolution of the experimental procedure could be very roughly estimated of the order of 100 µm. Idioma: Inglés DOI: 10.1149/1945-7111/ac60f2 Año: 2022 Publicado en: JOURNAL OF THE ELECTROCHEMICAL SOCIETY 169, 4 (2022), 044503 [10 pp.] ISSN: 0013-4651 Factor impacto JCR: 3.9 (2022) Categ. JCR: MATERIALS SCIENCE, COATINGS & FILMS rank: 7 / 20 = 0.35 (2022) - Q2 - T2 Categ. JCR: ELECTROCHEMISTRY rank: 16 / 30 = 0.533 (2022) - Q3 - T2 Factor impacto CITESCORE: 7.2 - Materials Science (Q1) - Chemistry (Q1) - Energy (Q1) - Physics and Astronomy (Q1)