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Control of Grain‐Boundary Pinning in Al 2 O 3 /ZrO 2 Composites with Ce 3+ /Ce 4+ Doping
Author(s) -
Xue Liang A.,
Meyer Karsten,
Chen IWei
Publication year - 1992
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.1151-2916.1992.tb04147.x
Subject(s) - microstructure , materials science , grain boundary , intergranular corrosion , doping , dopant , cerium , phase (matter) , grain growth , analytical chemistry (journal) , intergranular fracture , electron microprobe , valence (chemistry) , mineralogy , composite material , metallurgy , chemistry , optoelectronics , organic chemistry , chromatography
The control of the microstructure of Ce‐doped Al 2 O 3 /ZrO 2 componsites by the valence change of cerium ion has been demonstrated. Two distinctively different types of microstructure, large Al 2 O 3 grains with intragranular ZrO 2 particles and small Al 2 O 3 grains with intergranular ZrO 2 particles, can be obtained under identical presintering processing conditions. At doping levels greater than ∼ 3 mol% with respect to ZrO 2 , Ce 3+ raises the alumina grain‐boundary to zirconia particle mobility ratio. This causes the breakaway of grain boundary from particles and the first type of microstructure. On the other hand, Ce 4+ causes no breakaway and produces a normal intergranular ZrO 2 distribution. The dramatic effect of Ce 3+ on the relative mobility ratio is found to be associated with fluxing of the glassy boundary phase and is likewise observed for other large trivalent cation dopants. The ZrO 2 second phase acts as a scavenger for these trivalent cations, provided their solubility limit in ZrO 2 is not exceeded.