Evaporation of NaCl Cleavage Planes in Vacuum

Abstract

Cleavage planes of NaCI (99.999%) were produced in air and heated in vacua of 10-'-10-6 Torr between 454° and 593°C. Reproducible variations in pit densities were observed between 10 6 and 10 2 cm-2 • Evidence IS presented showing that these variations are due to changes in surface contamination. Matching cleavage planes showed no correlation in their pit sites; slip lines and small-angle boundaries showed no perferred pitting. It is concluded that dislocation emergence points per se are not sufficient for the formation of thermal pits in vacuum of 10-6 Torr. The evaporation process caused the development of (1) pits with different slope angles and (2) slope-dependent variatIOns of their shape and faceting behavior. There was no rounding of leading or trailing edges between surface sections of different inclinations. These observations cannot be explained in terms of evaporation theories which have been suggested before. A different interpretation in terms of surface energy is given. A numerical estimate for the required variations in surface energy is included.

A simple technique for interference microtopography

“…As the fringe width is inversely proportional to the wedge angle care must be exercised in placing the cover slide on the sample surface, so that a suitable fringe spacing results. The interferograms presented here are comparable in quality to those obtained by using an interference microscope (Budke 1969). The quality of the intefferograms can be enhanced by coating the surface of the sample with silver, however the interferograms presented in this article were taken without providing any such coating on the sample surface.…”

Структура и механизмы образования наноразмерных пленок примесного металла кобальта и никеля в монокристаллах LiF и MgF-=SUB=-2-=/SUB=-

“…Гринберг [32] и Будке [33] в своих исследованиях не нашли корреляции между дислокациями и термическими ямками травления. Также эти авторы не нашли определенной связи термической ямки с примесями.…”

Monitoring Sintering / Densification and Crystallization / Grain-Growth in Tl-Based High Temperature Superconductors by Electrical Conductivity Measurements

“…Patel and Chaudhari (1969) believed in the correspondence of the etch patterns produced by chemical and thermal etchings. Budke (1969) held the view that for the formation of thermal etch pits on NaCl cleavages, the surface contamination due to environment, and not the dislocations, play a vital role.…”