To explain the morphology influenced by the gelation temperature requires a multidisciplinary knowledge. A further investigation, a high-resolution TEM (HRTEM), was conducted to clarify the microstructure and crystal feature of the ZrB2 particles. At a lower temperature, the rate of nucleation was faster than that of growth, whereas the monomer concentration was sharply decreased [30]. Such slow growth conditions favored the formation of a sphere-like shape (see Fig. 5(a)). With increasing the gelation temperature, Figs. 5(b) and 6(a) show that a particle chain of ZrB2 was evolved at 75 °C. The HRTEM image of ZrB2 particle chain revealed that each unique particle chain was composed of several sphere-like particles. These sphere-like particles aligned one by one to form a polycrystalline particle chain of ZrB2 and shared a quasi-parallel crystal orientation at the grain interfaces (see Fig. 6(a) and (b)). It is notable that the interface between the two grains in the rectangle region (magnified in Fig. 6(b)) involved edge dislocations (arrowhead). With the temperature further increased, adjacent particles fused together to form strong links resulting in the evolution of ZrB2 rods (see Figs. 5(c) and 6(c)). In the same way, the adjacent grains shared a common crystallographic orientation, followed by joining of these grains at a planar interface with edge dislocations (arrowhead) (see Fig. 6(d)). It also may be found from the HRTEM image that these particle chain/rod shared {0 0 1} lattice fringes with interplanar spacings of 0.35 nm.