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On crystal growth of orthorhombic alkali acid phthalates. An application of fourier transform of crystal morphology to tracht and habitus
Author(s) -
Schwarz H.,
Fiedler R.,
Follner H.
Publication year - 1985
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170200310
Subject(s) - orthorhombic crystal system , alkali metal , crystallography , chemistry , crystal (programming language) , crystal growth , potassium , crystal structure , organic chemistry , computer science , programming language
The orthorhombic alkali acid phthalates crystallize in three different structure types. The structure of potassium acid phthalate (P2 1 ab) can be regarded as a basic structure. The elementary cells of ammonium (Pcab) and sodium crystals (B2ab) contain two potassium structure units which are connected to each other along [001] by a symmetry centre in the first case and by a twofold rotation axis in the second case. It will be shown that close morphological relations between the crystals also can be observed. The morphological lattices of the substances agree fairly well with the centres of gravity of the phthalate ions (HP). The reciprocal crystals have mmm (KHP, NH 4 HP) and mm2 symmetry (NaHP), respectively. The growth rates of the faces are proportional to the areas of the net plane meshes, divided by the number of the morphological units per growth layer. The thickness of the growth layer is determined by the morphological extinction rules. The specific surface energies are proportional to the surfaces of the reciprocal crystals parallel to the crystal faces, divided by the areas of the net plane meshes. The theoretical growth and equilibrium forms of the hydrogen phthalates are in good agreement with the experimental observations.