Furthermore, the influence of the gelation temperature on the morphology of the samples was also investigated, and the SEM images of the as-calcined samples are shown in Fig. 5. It is observed that the morphology of the samples was affected by the gelation temperature. For the ZrB2 sample gelated at 65 °C, the SEM revealed a sphere-like morphology of ZrB2 nanoparticles (see Fig. 5(a)). At 75 °C, the morphology showed a particle chain (see Figs. 5(b) and 6(a)). With the increasing of the temperature to 85 °C, the morphology of the ZrB2 particles evolved to a rod-like shape. Additionally, the size of ZrB2 particle also increased notably with the increasing of the gelation temperature.