A Spectrometer for Studying Single Crystals Using the Method of Synchrotron Radiation Diffraction at Near-Backscattering Angles

A spectrometer has been developed at the beamline EXAFS-D station of the Kurchatov synchrotron-radiation source at the Kurchatov Institute National Research Center for the precision determination of relative variations in the lattice parameters of single crystals. The spectrometer allows measurements of small (up to 3 × 10−7) relative variations in the lattice parameter, which may be caused by stoichiometry violation or external actions, e.g., inverse piezoelectric effect. The method of X-ray diffraction in a geometry that is close to backscattering at angles as large as 179.5° is implemented in the spectrometer. Using a synchrotron source, it is possible to select the radiation wavelength for tuning the spectrometer to the near-backscattering diffraction geometry. The equipment of the spectrometer allows simultaneous monitoring of the lattice-parameter variation and mapping of the elemental composition over the crystal surface.