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Measurement of Oxygen Diffusion in Dy 2 O 3 and Gd 2 O 3 by Studying High‐Temperature Oxidation of the Metals
Author(s) -
BASLER D. B.,
BERARD M. F.
Publication year - 1974
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1974.tb11379.x
Subject(s) - diffusion , oxide , oxygen , ionic bonding , analytical chemistry (journal) , metal , electrical resistivity and conductivity , monoclinic crystal system , ionic conductivity , materials science , ionic radius , single crystal , crystallography , chemistry , crystal structure , ion , thermodynamics , metallurgy , physics , organic chemistry , electrode , chromatography , electrolyte , electrical engineering , engineering
Studies of the oxidation of Gd and Dy at P O2 's from 10 −0.3 to 10 −14.5 atm and temperatures from 727° to 1327°C indicate both semiconducting and ionic‐conducting domains in the sesquioxides formed. At higher temperatures, where dense coarsegrained oxide layers developed, the rate of oxidation in the high‐ P 02 semiconducting domain yielded oxygen diffusion coefficients in Dy 2 O 3 in excellent agreement with literature values derived from oxidation of partially reduced oxide single crystals. Under the same conditions, the oxidation of Gd yielded oxygen diffusion coefficients in cubic Gd 2 O 3 which are considerably below literature values for monoclinic single‐crystal Gd 2 O 3 . At lower temperatures, porous scales were formed, and apparent diffusion coefficients derived from oxidation rates show a smaller temperature dependence than the high‐temperature data. At low P O2 , the oxides behave as ionic conductors, and metal oxidation rates result in estimates of the electronic contribution to the electrical conductivity of the order of 10 −6 to 10 −7 Ω −1 cm −1 .