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Autoradiographic Investigations on the Incorporation of Ca Ions in KCl Crystals during Kyropoulos Growth
Author(s) -
Beleites H.,
Fröhlich F.
Publication year - 1972
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19720071204
Subject(s) - cleavage (geology) , ion , crystallography , doping , materials science , crystal (programming language) , dissociation (chemistry) , crystal growth , analytical chemistry (journal) , chemistry , chromatography , composite material , organic chemistry , optoelectronics , fracture (geology) , computer science , programming language
Ca doped KCl crystals were grown by the Kyropoulos method. 10 −5 to 10 −3 mole fractions of Ca (as CaCl 2 with a small amount of Ca‐45 (β‐emitter)) were added to the melt. By autoradiography of suitable cleavage planes the incorporation of the Ca ions was found to take place preferentially in a periodic manner parallel to the solid liquid interface. In the case of a rotating seed there is a segregation process in which only one zone of maximum Ca content is built up like a helix throughout the whole crystal, the axis being identical with the growth axis of the crystal and the slope of the helix corresponding to the growth rate per seed rotation, this leading to striations of long range periodicity on vertical cleavage planes. In the case of a non‐rotating seed there is a different segregation process including a periodical incorporation too, but in discrete layers of relatively small separation parallel to the solid liquid interface in short range periodicity. Explanations for the segregation phenomena are given in terms of periodically varying effective growth rates related to periodic temperature fluctuations in the neighbourhood of the solid liquid interface.