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Seeman–Bohlin X‐ray diffractometer for thin films
Author(s) -
Feder R.,
Berry B. S.
Publication year - 1970
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/s0021889870006441
Subject(s) - diffractometer , crystallite , optics , monochromator , materials science , diffraction , thin film , scattering , powder diffractometer , physics , nanotechnology , scanning electron microscope , wavelength , metallurgy
A focusing Seeman–Bohlin diffractometer of 20 inches diameter has been designed and constructed with special emphasis on its suitability for the examination of polycrystalline thin films. The apparatus employs a pyrolytic graphite monochromator crystal to obtain a high‐intensity beam, which is incident upon the specimen at a selected low angle of incidence, so as to increase the path length through the sample. Atmospheric scattering of the diffracted rays is reduced substantially by the use of a helium chamber. The attitude of the X‐ray counter is controlled by a simple servomechanism, without the use of lever arms. The unit is operated by a data acquisition and control system, and executes a preset step‐scan with data collection on punched cards or paper tape. The performance of the diffractometer is illustrated by a variety of measurements made on metallic films of 150 to 8000 Å in thickness. The results demonstrate the utility of the diffractometer for precise lattice parameter measurements, for the determination of internal strains and crystallite size, and as a tool for studying reactions in multicomponent or multilayer films.