View of a 25%v.f. sample before the field is turned on. The spheres have sedimented to the bottom. The bottom few layers are hexagonally packed, and the layers above are less densely packed. The two electrodes are at the bottom of the image and at the white line (separated by ~70 microns, and the electric field will be applied parallel to the view plane.

View after an electric field ~1kV/mm has been applied for about 15 minutes. The particles have formed into interlinked columns with regions devoid of particles. Within the columns, the particles are arranged as misaligned BCT clusters. The electric field is parallel to the view, indicated by the white arrow.

View of the 'columns' perpendicular to the electric field. The interlinked columns separated by void regions can be seen.

A section through the sample before the field was turned on. The view is parallel to the electrode plane. At this volume fraction, most of the sample is in the solid state, this section shows hexagonal ordering parallel to the electrodes. (gravity is perpendicular to the electrode).

The same section about 6 hours after the field (~1kV/mm) was turned on. Areas of the sample have transformed into the BCT structure while some areas remain as hexagonal planes parallel to the electrodes. The transition occurs via defects in the hexagonal ordering.