Quantum mechanics

Supersaturation

Adsorption

Chemical physics

Materials science

Chromatography

Mineralogy

Kinetic energy

Dissolution

Physical chemistry

Thermodynamics

Physics

Organic chemistry

Mathematics

Hillock

Geometry

Composite material

Analytical Chemistry (journal)

Crystallography

Chemistry

Surface energy

Growth rate

Dislocation

Journal of Crystal Growth

A technique has been developed to automatically measure normal growth rates as low as 3 × 10-9 cm/s and higher, the tangential growth rates and hillock slopes. The method was applied to the (101) ADP growth in the kinetic regime at various supersaturations 0.05% < σ < 2.5% and pH = 3.6−5.6. The direct incorporation model allows determination of the effective step free energy, ⋍ 8.5 × 10−7 erg/cm (corresponding to the surface energy of 16 erg/cm2), and the step kinetic coefficient (i.e. the rate of incorporation at the steps), ⋍ 0.3 cm/s. The rates of growth (incorporation) and dissolution at steps were found to be nearly equal, whereas the dissolution rates at dislocations exceed the growth rates by up to 3 times. This effect is considered as evidence of a stress field around a dislocation. At supersaturations σ < σ∗ = 0.25% and pH =3.6, the growth stopped completely. At 0.25% < σ < 0.35%, irregular growth, and at σ > 0.35%, regular growth were observed. Increase in pH results in a shift of these supersaturation ranges to lower values. After an exposure at σ < σ∗, the not-growing face became poisoned: when, after the exposure, the supersaturation is raised to a value σ > σ∗, the face still does not grow for several minutes. If this new value σ > σ∗ is high enough, the growth sta immediately. This phenomenon is attributed to the formation of stoppers previnting propagation of steps (Cabrera-Vermilyea mechanism). The minimal supersaturation above which the growth starts is a direct function of the exposure duration and allowed us to estimate the surface density of stoppers and their adsorption isotherm.

Regular and irregular growth and dissolution of (101) ADP faces under low supersaturations