Sweegers-C; van-Enckevort-WJP; Meekes-H; Bennema-P;
Hiralal-IDK; Rijkeboer-A
JOURNAL-OF-CRYSTAL-GROWTH. FEB 1999; 197 (1-2)
: 244-253
Abstract:
Gibbsite, gamma-Al(OH)3, is an important
technical product, used mostly as an intermediate in the production of
aluminium. According to the literature, the morphology of natural and industrial
gibbsite crystals is pseudohexagonal with {0 0 1} basal, and {1 0 0} and
{1 1 0} side faces. Laboratory experiments on the growth of gamma-Al(OH)3
crystals from unseeded sodium aluminate/sodium hydroxide solutions result
in crystals land agglomerates) with various morphologies, such as lozenge-shaped
or hexagonal plates as well as prisms. Optical polarisation microscopy
shows many of the crystals to be twinned. Three kinds of reflection twin
with both mirror and composition planes {1 1 0}, {0 0 1} and {1 0 0} were
identified. In addition, [1 3 0] rotation twins with :0 0 1) as composition
plane were found. The effect of various kinds of twinning on the growth
morphology and growth kinetics of gamma-Al(OH)3 crystals is
studied.