CHARACTERIZATION OF LONG-PERIODIC LAYERED STRUCTURES BY X-RAY-DIFFRACTION .2. LATTICE DISTORTION OF LANGMUIR-BLODGETT-FILMS OF LEAD STEARATE

X-ray 00l reflections from three kinds of 25-layer Langmuir-Blodgett films of lead stearate were measured, using a high resolution reflection Kratky camera system. The accurate thicknesses of a bilayer were evaluated by the modified Bragg law. According to the microstrain, the paracrystalline and the Wilson models, line breadths of the reflections were separated into broadening due to crystallite size and lattice distortion. The crystallite sizes thus obtained agree well with those calculated from the thickness and number of bilayers. Regardless of which distorion model is used, gaussian profiles always give a larger lattice distortion than Cauchy profiles. To describe the lattice distortion of the present specimens, the microstrain and the Wilson models are more favourable than the paracrystalline model. The lattice distortion has been proven to be very sensitive to preparation conditions such as surface pressure and surface treatment of the substrate. © 1990.