Zigzag configurations of Hafnium carbide nanowires synthesised by chemical vapour deposition below the eutectic temperature

Hafnium carbide nanowires were synthesised by a Ni-catalysed vacuum chemical vapour deposition method below the eutectic temperature of the Ni-C-Hf alloy. The zigzag growth behaviour of the hafnium carbide nanowires resulting from metastable growth was investigated by transmission electron microscopy in order to understand the sub-eutectic growth. Three typical zigzag configurations at joint angles of ∼125°, 45°, and 90° can be observed from the synthesised nanowires, where the structure with an angle of ∼125° is the most common, formed via a change in the growth direction from [211] to [011], or vice versa. The 45° zigzag structure is the second most common and is formed by alternating the axial direction three times between 〈011〉 and 〈001〉. The number of the zigzag structures with a 90° angle is the most rare among the three types and is formed by the change in growth direction between two energy-equal directions, from [110] to [110]. Although alternating the growth direction brings about the zigzag geometry, the zigzag structured hafnium carbide nanowires have a single-crystal structure. In addition, the surface energies of the crystal planes play an important role in the growth of the hafnium carbide zigzag nanowires.