A TEM image and selected area electron diffraction pattern are shown in Fig. 2. In Fig. 2a, the material exhibits slightly agglomerated particle morphology. The particle size is estimated in the range of 10–20 nm in diameter. In Fig. 2b, the diffraction rings match the hexagonal ZrB2 (1 0 0), (1 0 1) and (1 1 0) planes, in good agreement with the XRD results.