Head: Jiří Hybler
Some physical measurements, optical or magnetic should be done using single crystal specimens aligned in a given orientation with respect to crystal axes, as their properties are anisotropic (dependent on the direction). Orienting of such specimens is done in the Laboratory for orienting single crystals.
In most cases, bulk crystals of size of several cm are studied. The classical back-reflection Laue X-ray diffraction method is used, sometimes combined with Buerger precession method. If possible, crystals are checked optically and eventually pre-oriented with aid of crossed polarizers.
Experimental setting is apparent in the Figure. The crystal studied, glued on the substrate is attached on the special holder allowing, in cetrain extent, rotation, tilt and shifts. From the arrangement of diffraction spots on the photograph the correction angles are determined. After setting into the correct position, the crystal together with a holder is mounted onto a saw and oriented specimens (usually plates or prisms) are cut.
The back-reflection Laue photographs are interpreted with the Greninger chart, available in the webpage: http://www-xray.fzu.cz/xraygroup/www/grchart.html.
More details about the laboratory and about the method can be found in the webpage: http://www.xray.cz/ms/bul2010-2a/hybler.pdf.
Orienting of crystals are performed mostly in cooperation with the Department of Optical Materials, Department of Magnetic and Superconductors, as well as with researchers outside the Institute of Physics. Other interested researchers are welcome.
