[001]. The appearance of these reflections in our data may suggest the 'down-chain' samples exhibit Pbcm space group symmetry rather than the A21am packing reported by Dorset (Figure ). Notably, both orientations closely resemble SAED patterns reported by Dorset and colleagues. However, the (110) reflections are symmetry allowed in Pbcm whereas very similar spots can be seen in simulated SAED patterns for the A21am structure when viewing down the [011] axis. This axis is only a small 3° tilt from the [001] axis (Figure ). The patterns simulated from the Pbcm [001] direction and the A21am structure [011] direction are not readily distinguishable. The appearance of strong bend contours (Figure ) indicates there is some variation in the crystal orientation across the field of view, and so contributions from A21am {111} reflections cannot be excluded. In either case, these crystals are in the 'down-chain' orientation.