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Aluminum Titanate Formation by Solid‐State Reaction of Coarse Al 2 O 3 and TiO 2 Powders
Author(s) -
FREUDENBERG B.,
MOCELLIN A.
Publication year - 1988
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.1151-2916.1988.tb05755.x
Subject(s) - nucleation , materials science , metastability , titanate , activation energy , phase (matter) , aluminium , kinetics , chemical engineering , mineralogy , thermodynamics , chemistry , metallurgy , ceramic , physics , organic chemistry , quantum mechanics , engineering
Reaction kinetics in a coarse equimolar powder mixture were slow enough to allow for the different stages to be identified, notably in the lower and higher temperature ranges, respectively. In the former ( T ≤ 1600 K), Al 2 TiO 5 nucleation was hindered by the strain energy contribution to the overall driving force. The setting up of metastable layer sequences Al 2 TiO 5 /TiO 2 /Al 2 O 3 was found to occur generally during subsequent growth. The high Al mobility in the TiO 2 provided a rapid aluminum transport from the metastable Al 2 O 3 /TiO 2 interface to the TiO 2 /Al 2 TiO 5 front. At temperatures above ∼1700 K the Al 2 O 3 /TiO 2 interface was very rapidly sealed off by Al 2 TiO 5 formation. Reactant transport across the Al 2 TiO 5 was slow because of the low mobilities in the product phase. Therefore, much lower product growth velocities were observed at higher temperatures than at lower temperatures.