Premium
Etch pit morphology and calcium sulphate growth on {111} faces of calcium fluoride crystals etched in sulphuric acid
Author(s) -
Sangwal K.,
Desai C. C.,
John V.
Publication year - 1979
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.19790140109
Subject(s) - whiskers , morphology (biology) , etching (microfabrication) , hexagonal crystal system , calcium , materials science , octahedron , crystallography , dislocation , crystal growth , chemistry , chemical engineering , crystal structure , metallurgy , nanotechnology , composite material , biology , layer (electronics) , engineering , genetics
An investigation of the etching behaviour of cleaved octahedral faces of calcium fluoride crystals in sulphuric acid of different concentrations and at various temperatures is carried out. It is observed that the morphology of dislocation etch pits depends on the temperature and concentration of the acid. With an increase in the acid concentration, growth of whiskers, elongated platelets, hexagonal and dice‐shaped elevations, spherulites and sheaves is observed. Temperature of the etchant also has an effect on their formation. By X‐ray diffraction techniques, the compounds forming the whiskers and elongated platelets, and hexagonal and dice‐shaped features are identified as CaSO 4 · 2 H 2 O and CaSO 4 , respectively. The mechanism of the growth of CaSO 4 · 2 H 2 O and CaSO 4 and the change in the morphology of selective etch pit are discussed.