Growth Kinetics and Morphology of Barite Crystals Derived from Face-Specific Growth Rates

We
investigate the growth kinetics and morphology of barite (BaSO4) crystals by measuring the growth rates of the (001), (210),
(010), and (100) surfaces using vertical scanning interferometry.
Solutions with saturation indices 1.1, 2.1, and 3.0 without additional
electrolyte, in 0.7 M NaCl, or in 1.3 mM SrCl2 are investigated.
Face-specific growth rates are inhibited in the SrCl2 solution
relative to a solution without electrolyte, except for (100). Contrarily,
growth of all faces is promoted in the NaCl solution. The variation
of face-specific rates is solution-specific, which leads to a change
of the crystal morphology and overall growth rate of crystals. The
measured face-specific growth rates are used to model the growth of
single crystals. Modeled crystals have a morphology and size similar
to those grown from solution. Based on the model the time dependence
of surface area and growth rates is analyzed. Growth rates change
with time due to surface area normalization for small crystals and
large growth intervals. By extrapolating rates to crystals with large
surfaces areas, time-independent growth rates are 0.783, 2.96, and
0.513 mmol·m–2·h–1,
for saturation index 2.1 solutions without additional electrolyte,
NaCl, and SrCl2, respectively.