Thermal Etching of Sodium Chloride

Abstract

Preliminary results obtained with NaCl thermally etched in air for short periods (from 15 min to 4 h) are reported. It is found that several surface structures appear successively with the corresponding transition patterns, emphasising the dynamic character of the process. The results are interpreted in terms of the classical theories of crystal growth, and as such, offer a direct confirmation of them.

Thermal etching of (100) surfaces in sodium chloride single crystals

“…5): with symmetric diagonals, with one symmetric and one nonsymmetric diagonal, and with two non-symmetric diagonals. These pyramidal pits are of the same type as those associated with dislocations, found by Gilman, Johnston & Sears (1958) on chemical etching of LiF crystals, and by Mendelson (1961) in sodium chloride single crystals. The results are summarized in Table 2.…”

“…6. It was observed that the pits were approximately circular from the very beginning so they are probably not the result of the evolution of square pits, as Grinberg (1963) proposed. The pits have a definite origin and may be associated with an imperfection in the crystal.…”

“…temperature near the melting point), pits and other corrosion figures are produced due to the evaporation of the crystal. Grinberg (1963) reported that no relationship was found between the development of the pits and the structural crystal defects in sodium chloride single crystals, but that the pits are produced when the surface is changing to higher equilibrium states; however, a relationship between evaporation pits and crystal defects was shown by Patel, Bahl & Vagh (1965) for the case of sodium chloride.…”

The Action of Adsorptive Inhibitors in Some Corrosive Systems

“…The existence of a balance between diffusion and interface control in evaporating systems is suggested by the tendency to depart from crystallographic morphologies when the surface temperature is raised, as exemplified by studies on the alkali halides (10,18), germanium (6), and diamond (38). In the work of Kern and Pick (18) on evaporation of some alkali halides, the surfaces exhibit the types of morphologies discussed herein for lithium fluoride in aqueous environment.…”

Epitaxic growth of [2,3,9,10,16,17,23,24-octacyano-29H,31H-phthalocyaninato(2–)]metal complex crystals

“…6 shows a representative electron micrograph of the film. As is well known, when alkali halides are etched thermally in vacuum, their (001) surfaces exhibit evaporation pits and other corrosion figures (Grinberg, 1963). A rectangular contour in the figure corresponds to a plateau which is made by thermal etching, and it reveals the [100] and [010] directions of the KCI crystal.…”