Die Vorgeschichte eines Kaliumchlorid-Einkristalls wird besonders deutlich an den Spaltflächen beim Verdampfen unterhalb des Schmelzpunktes. Innerhalb engbegrenzter Temperaturbereiche bilden sich 1. rechtwinkelige Lamellenstrukturen (unterhalb 720°C), 2. Übergangsstrukturen (720-740°C) und 3. kreisförmige Lamellenstrukturen (740-770°C). Zeitrafferaufnahmen im Phasenkontrastmikroskop.

The thermal history of a crystal plays a very important part in the visual and electrical examination of alkali halides. For this reason, crystal surfaces are examined at high temperatures. During evaporation in air the fracture planes show characteristic changes. Thus, below the melting point of 770°C, various surface structures are observed. Rectangular lamella structures form within narrowly defined temperature ranges below 720°C. Between 720°C and 740°C intermediate structures occur and circular lamella structures appear between 740°C and 770°C. The observations were carried out with the aid of a phase contrast microscope. The micro-cinematographic exposures were made using time lapse photography with ratios of 3:1 to 144:1.