This powder x-ray diffraction apparatus was used from 1964 to 2009 in undergraduate experiments.
X-ray diffraction is widely used to determine the atomic structure of crystal where atoms, ions or molecules are regularly arranged in space. When monochromatic and collimated x-rays are directed onto crystalline sample ground into fine powder or polycrystalline sample, x-rays are observed only along some cones. Tips of the cones are on the irradiated position and the central axis is the incident direction. Since the wavelength of x-rays is close to the interatomic distance, x-rays are diffracted by the crystal. The crystal structure of the sample is analyzed by utilizing the fact that the Bragg’s law determines the diffracted angles of x-rays. The powder diffraction method is also called Debye-Scherrer method.
Three low cylinders seen in the upper parts in top two pictures are Debye-Scherrer cameras. Samples are set at the center of each camera. There are small windows from which x-rays are emitted in the center region surrounded by the cameras. X-rays are introduced into the cameras through collimators and impinge onto the sample. A rectangular film strip is set on the inside wall of each cylinder. While the samples are exposed to x-rays, the apparatus is shielded by thick lead plates to protect operators against radiation exposure.
Some black curves are observed on the film after exposure as seen in the right bottom picture. The center of the hole of the film is on the incident direction of the x-rays. The curves of intersection between the cones described above and the film are symmetrically distributed. As is the case for medical radiographs, the film is observed on a Schaukasten, which has a flat piece of backlit opaque glass.
The top left: Powder x-ray diffractometer. Three low cylinders are Debye-Scherrer cameras. Lower part is control unit for x-ray tube.
The top right: Powder x-ray diffractometer.
The right in the middle: Control unit for x-ray tube.
The bottom right: Observation of Debye-Scherrer rings on film with Schaukasten.