X-Ray Diffractometers
X-Ray Diffractometer is an instrument used in studying diffraction, as in the determination of crystal structure by diffraction of X-rays. An x-ray diffractometer illuminates a sample of material with x-rays of known wavelength, moving the sample and detector in order to measure the intensity of the diffracted radiation as a function of beam and sample orientation. From the resulting intensity versus angle plot much can be inferred about the structure of the material.
The X-ray diffractometer is used to solve various problems of X-ray diffraction analysis. It permits the intensity of radiation diffracted in a specified direction to be measured with an accuracy of tenths of a percent; diffraction angles can be measured with an accuracy of tenths of a minute. X-ray diffractometers can be used for such tasks as the phase analysis of polycrystalline objects, the investigation of textures, the orientation of single-crystal blocks, the obtaining of a complete set of intensities of reflections from a single crystal, and the structure analysis of substances under various external conditions.
The X-ray diffractometer consists of an X-ray source; an X-ray goniometer, in which the specimen under study is placed; a radiation detector; and an electronic measuring and recording device. Unlike X-ray cameras, which use photographic film, X-ray diffractometers use quantum counters—scintillation, proportional, semiconductor, or Geiger counters as Detectors. The diffraction pattern of a specimen is obtained in an X-ray diffractometer in a sequential manner: the counter moves in the process of measurement and records the radiant energy incident on it over a certain time interval. X-ray diffractometers have better accuracy, greater sensitivity, and higher speed than X-ray cameras. The process of obtaining data in an X-ray diffractometer can be completely automated, since there is no need to develop a photographic film. Such an automatic X-ray diffractometer is controlled by an electronic computer, and the data obtained are fed to the computer for processing. General purpose X-ray diffractometers can be used for different X-ray diffraction investigations by fitting attachments to the goniometric device. Large laboratories use special diffractometers designed to solve particular problems of X-ray diffraction analysis.