Premium
The structure of a multilayer of lead stearate
Author(s) -
Stephens J. F.,
TuckLee C.
Publication year - 1969
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s002188986900639x
Subject(s) - monoclinic crystal system , orthorhombic crystal system , crystallography , stearate , stearic acid , crystal structure , electron diffraction , materials science , chemistry , diffraction , optics , composite material , physics
A study has been made of the molecular and crystallographic structures of Langmuir–Blodgett multilayer films of lead stearate. Electron microscopy and diffraction were used in the examination of such a film which had separated from the glass slide on which it had been formed. The films consist of a large number of three‐dimensionally ordered lead stearate crystals arranged in near‐perfect alignment, with the longest axes of their unit cell projecting from the plane of the supporting substrate. The unit cell of the lead stearate crystal is either monoclinic with the space group P 2 1 / a or orthorhombic with the space group P 2 1 2 1 2. The former is considered to be rather the more likely. The major lattice spacings are 4.96 Å (100), 7.38 Å (010) and 47 Å (001). The β angle of the monoclinic unit cell is not known but is probably within a few degrees of 90°. The lead atoms are in special positions in the basal plane, regardless of which is the correct unit cell, and the hydrocarbon chains make an angle of 62±5 ° with the basal plane. Any free stearic acid in the films occurs as a separate phase.