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High‐Temperature Conductivity and Creep of Polycrystalline AI 2 O 3 Doped with Fe and/or Ti
Author(s) -
EIAIAT M. M.,
HOU L. D.,
TIKU S. K.,
WANG H. A.,
KRÖGER F. A.
Publication year - 1981
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.1151-2916.1981.tb10252.x
Subject(s) - creep , materials science , ionic conductivity , grain boundary , acceptor , crystallite , activation energy , ionic bonding , conductivity , doping , partial pressure , grain size , analytical chemistry (journal) , diffusion creep , dopant , diffusion , valency , mineralogy , oxygen , microstructure , composite material , metallurgy , thermodynamics , electrolyte , chemistry , condensed matter physics , ion , electrode , philosophy , linguistics , chromatography , physics , optoelectronics , organic chemistry
Partial ionic and electronic dc conductivities and compressional creep rate were measured for hot‐pressed poly crystalline AI 2 O 3 made from AI‐isopropoxide (AI 2 O 3 (II)). The undoped material was found to contain 1.5×10 18 cm −3 fixed valency acceptors (Mg). Properties of undoped material and material doped with Fe or Ti were investigated as a function of grain size, dopant concentration, oxygen pressure, and temperature. No fast ionic conduction along grain boundaries is found in either acceptor‐ or donor‐dominated material. Absolute values of self‐diffusion coefficients calculated from conductivity and creep indicate that both effects are limited by migration of AI, involving V AI “in donor‐, AI,” in acceptor‐dominated material. In creep, oxygen is transported along grain boundaries in a neutral form (O i p ). The p O2 dependence of σ t and σ h are as expected on the basis of a defect model. That of creep is weaker for reasons that are not entirely clear. An ionic conductivity with low activation energy, observed at low temperature, is attributed to the presence of AI‐silicate second phase.