The crystal was adhered to a rectangular piece of Kapton tape to prevent it from moving and fluctuating under the N2 gas stream used for temperature control. The crystal had a straight configuration before the screw was tightened. The position of the microfocus X-ray beam (height: structure. The ω-scan range was restricted to -45° to 45° to avoid the X-ray irradiation of positions other than the centre of the crystal. As summarised in Figure , the a-axis length of the straight crystal was nearly independent of the beam position and similar to that in the MT state.