Chemical preparation of dielectrics for studying their microtopography by the SEM

Abstract

A procedure for the chemical preparation of dielectrics to make their surfaces conductive is proposed. Its simplicity and rapidity, as well as the possibility of using it to study etching kinetics of specimen surface morphology are noteworthy. The procedure is demonstrated by the interaction of F‐apatite with acids. The procedural steps include careful attention to the washing of the specimen following its interaction with an acid and to its drying thereafter. The composition of the washing solution and the washing time must be carefully controlled. Positive results are obtained for the interaction between F‐apatite and phosphoric, hydrochloric, nitric acids and between glass and hydrofluoric acid. Acetone was employed as the washing solution and in all cases sharp images of the specimen surface were obtained in the SEM. The subsequent washing of the specimen in water restored the dielectric properties of its surface. By sequentially etching, drying, and observing the specimen in the SEM, a series of images was obtained of an area of the surface as it was being etched. This series of images permitted determination of the growth rate of etched pits.

Process of epitaxial crystal growth for CaSO4 · 0.5H2O on a surface of dissolving fluorapatite crystals studied by scanning electron microscopy

“…This article continues the earlier published investigation of fundamentals for phosphorus-containing fertilizer production by scanning electron microscopy (SEM) (Dorozhkin 1995, Dorozhkin and Nikolaev 1993, Dorozhkin et al 1992) and aims to estimate the main stages for calcium sulfate epitaxial crystallization on the surface of natural fluorapatite (FAP) (Ca 10 (PO 4 ) 6 F 2 ) crystals. The choice of the object and the experimental conditions of the investigation was made according to modern technologic practice of wet-process phosphoric acid production by the hemihydrate method (Becker 1989, Kopylev 1980 Under experimental conditions, the CaSO 4 • 0.5H 2 O crystals obtained have fastened onto the FAP crystal surface, covered it, and formed a continuous coating of CaSO 4 • 0.5H 2 O.…”

“…5) and inside etch pits (Figs. 4a,b and 5, center), having already formed on the FAP crystal surface under the chosen experimental conditions (Becker 1989, Dorozhkin 1995, Dorozhkin et al 1992, and references therein). Our careful investigations, however, have resulted in the conclusion that sometimes the formation centers of CaSO 4 • 0.5H 2 O star-like and besom-like aggregates are situated not only in the mentioned places.…”

“…The second group of experiments was based on a special technique for studying dielectrics by the SEM without any conductive coating deposition (Dorozhkin et al 1992). The experiments were carried out in the same heated vessel, but without any stirring because the purpose of this group was to study the details of crystal growth for individual CaSO 4 • 0.5H 2 O crystals.…”

“…As a result, series of successive photographs illustrating the process of epitaxial crystal growth for the same group of CaSO 4 • 0.5H 2 O crystals were obtained. The principles and details of the experimental technique have been published earlier (Dorozhkin et al 1992).…”

A study of the kinetics of topochemical reactions by scanning electron microscopy

“…As was shown in Dorozhkin et al (1991), the experimental procedures under consideration enable one to observe the relief of apatite crystal surface using SEM methods without applying a metal coating film. During the contact with acid solutions and subsequent short rinsing with water or acetone, a conducting phosphate layer is being formed on the surface of apatite crystals, thus making the application of a metal coating film not necessary.…”