Surface composition of ceramic CeGd–oxide

• Published in: Solid state ionics Vol. 112; no. 1; pp. 123 - 130
• Main Authors: Scanlon, P.J, Bink, R.A.M, van Berkel, F.P.F, Christie, G.M, van IJzendoorn, L.J, Brongersma, H.H, van Welzenis, R.G
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02-09-1998; Elsevier Science
• Subjects: Ceria; Composition; defects and impurities; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fuel Cells; Physics; Segregation; SOFC; Solid surfaces and solid-solid interfaces; Surface composition; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); 68.35.Dv; Segregation; 89.30.+f; Ceria; Fuel Cells; 82.80.Ms; 61.18.Bn; Surface composition; SOFC; 82.80.Yc; RBS; Inorganic compounds; Ternary compounds; Surfaces; Rare earth compounds; Experimental study; Oxide ceramics; Low energy; Gadolinium oxides; Ion scattering; Chemical composition; Solid electrolytes; Surface layers; Cerium oxides
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(98)00198-2

The atomic composition of the outermost atomic layers of gadolinium-doped ceria, Ce
0.8Gd
0.2O
1.9, was determined with Low Energy Ion Scattering (LEIS). Due to the surface sensitivity of this technique it was possible to determine that the outer 5 monolayers are Gd-enriched. The Ce/Gd ratio changes from 1 at the outermost surface to 4.2 in the `bulk'. When this ceria would be used as the electrolyte in a fuel cell, such a surface Gd enrichment could influence its operation. Only in the first monolayer was some Ca observed. No difference in surface composition was observed between samples sintered at 1300 and 1600°C, in spite of large differences in oxygen ionic-conductivity observed previously. At a depth of about 20 monolayers a sudden shift in surface conductivity is observed that might be correlated with a structural change of the material at the grain boundary. The quantification with LEIS was checked with Rutherford Backscattering Spectroscopy (RBS), giving good agreement for the bulk composition.