Effect of stress from the glue on single-crystal X-ray intensities at high or low temperatures

For high- or low-temperature single-crystal X-ray data collection, the glues used to bind crystals to silica rods may induce strong modifications of the intensities. When an yttrium iron garnet (YIG) crystal was cooled, reflections which were equivalent at room temperature became different. This is explained by strong stresses of the glue on the crystal which lead to an anisotropic modification of the secondary extinction. At low temperatures, `glues' such as beeswax or paraffin do not exert stresses.