Probing High Oxygen Activity in YSZ Electrolyte. Issue 4 (1st April 2022)

• Record Type: Journal Article
• Authors: Robles-Fernández, Adrián; Orera, Alodia; Peña, José I.; Merino, Rosa I.
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 4(2022)
• Publication Date: 2022-04-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac60f2
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : 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 −20 to 100 bar PO2 around 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 Tb 4+ and Pr 4+ formed give rise to intense optical absorption around 300–500 nm and to decreased reflectance. From the reflectance measurements it is shown that the Tb 4+ concentration increases as PO2 1/4, as correspond to the trapping of the holes generated upon the oxygen incorporation as Tb 4+ . This competitive absorption causes a decrease of the Tb 3+ luminescence. A quantitative relationship of the Tb 3+ luminescence intensity with PO2 at 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 μ m.