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On the Real Structure of Gypsum Crystals
Author(s) -
Follner S.,
Wolter A.,
Helming K.,
Silber C.,
Bartels H.,
Follner H.
Publication year - 2002
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 - 10.1002/1521-4079(200202)37:2/3<207::aid-crat207>3.0.co;2-l
Subject(s) - gypsum , crystallography , crystal structure , chemistry , materials science , mineralogy , composite material
X‐ray diffraction patterns of gypsum exhibit different reflection intensities, depending on the conditions under which the gypsum was manufactured. Pole figures and area detector images have shown that these differences in intensity result in large part from the formation of textures during the preparation of the powder. The differences in intensity of integrated area detection images suggest that gypsum crystals can be categorized as mosaic crystals. Weissenberg photographs confirmed this claim. Calculations of lattice energy based on the theory of reciprocal crystals indicated that interpenetration twins form according to known laws through isoepitaxial overgrowth. Crystallite pairs of gypsum were known intergrown at different angles with the (010)/(0 $\bar 1$ 0) and (010)/(010) faces. This results in six different layer arrangements. Energy was calculated by shifting one layer against another along a grid parallel to (010) and rotating it 360° around each grid point in increments of 10°. In all cases, an energetically favourable angle range was found for nearly every point on the grid.