Single-crystalline hafnium carbide nanowire growth below the eutectic temperature by CVD

• Single-crystal HfC nanowires were obtained below the eutectic temperature (TE) by CVD.
• The nanowires had diameters of ~50 nm and lengths of tens of microns.
• Most of the nanowires metastably grew along 〈112〉 crystal direction.
• The synthesis temperature greatly affected the product growth in diameter.
• Nanosize effects and curvature effects probably led to the VLS-type growth below TE.

Single-crystalline hafnium carbide (HfC) nanowires were synthesized by a Ni-catalyst-assisted chemical vapor deposition (CVD) method at 1025 °C below the eutectic temperature (TE). The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). XRD and EDX results indicate that well stoichiometric HfC nanowires were obtained. SEM and TEM investigations show the HfC nanowires possess typical diameters of ~50 nm and lengths of tens of microns. Most of the nanowires are grown along 〈112〉 crystal directions and the cluster/column interfaces at the wire tips parallel to the {011} crystal planes. Although the synthesis temperature of the nanowires is at least 75 °C lower than TE, the vapor -liquid -solid growth of the HfC nanowires still occurs probably due to nanoscale size effects and curvature effects. In addition, it is found that the diameters of the synthesized products increase when raising the synthesis temperature.