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Electrical Conductivity of A1 2 O 3 : Fe + Y
Author(s) -
KORIPELLA CHOWDARI R.,
KRÖGER FERDINAND A.
Publication year - 1986
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.1151-2916.1986.tb07389.x
Subject(s) - electrical resistivity and conductivity , diffusion , acceptor , analytical chemistry (journal) , oxide , activation energy , conductivity , solubility , oxygen , materials science , electrolyte , aluminium , doping , chemistry , inorganic chemistry , thermodynamics , metallurgy , condensed matter physics , electrode , physics , optoelectronics , organic chemistry , chromatography , electrical engineering , engineering
High‐temperature dc electrical conductivity and emf of oxygen concentration cells with A1 2 O 3 as the electrolyte were studied. The defect structure of α‐Al 2 O 3 doped with Fe and Y was investigated to test an explanation proposed for the favorable effect of Y addition to super alloys (Fe, Cr, Ni, Al) which leads to well‐adherent and nonconvoluted A1 2 O 3 oxide scales. Results indicate that Y is a singly ionizable donor in Al 2 O 3 and Y additions are effective in compensating Fe acceptors in A1 2 O 3 at iron concentrations up to the solubility limit of Y. At higher acceptor concentrations leading to a decrease in [ V “‘ Al ] and an increase in [Al … i ], incorporation of Y leads to a small increase in the concentration of V’” Al . This suggests that the mechanism proposed for the prevention of oxide scale spallation based on the Y donor action to suppress the bulk diffusion of aluminum interstitials created by the Fe acceptors cannot explain the effect. Energy level positions of Fe and Y in A1 2 O 3 are estimated, and values for electron and hole mobility at 1500°C are derived.