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The Rapid Formation of La(OH) 3 from La 2 O 3 Powders on Exposureto Water Vapor
Author(s) -
Fleming Peter,
Farrell Richard A.,
Holmes Justin D.,
Morris Michael A.
Publication year - 2010
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.1551-2916.2009.03564.x
Subject(s) - reactivity (psychology) , crystallite , water vapor , hydroxide , chemistry , hydroxylation , oxide , materials science , analytical chemistry (journal) , inorganic chemistry , crystallography , organic chemistry , medicine , enzyme , alternative medicine , pathology
The reactivity of various lanthana powders in air was studied. The materials rapidly hydroxylate to form a stable hydroxide, La(OH) 3 , at room temperature. Smaller amounts of an oxycarbonate species (La 2 O 2 CO 3 ) are also observed following air exposure. This oxycarbonate phase is stable to hydroxylation. All oxide materials synthesized here show rapid reactions so that 24 h of exposure to atmosphere is generally sufficient to cause complete hydroxylation at room temperature. The rate of reaction was related to the crystallite size as determined by XRD. The reaction was found to follow a two‐stage kinetic process, a relatively slow surface reaction followed by a rapid bulk reaction. The relevance of the reactivity of these powders is discussed.