Screw Dislocation Assisted Spontaneous Growth of HfB 2 Tubes and Rods

The mechanism of anisotropic growth of HfB 2 rods has been discussed in this study. HfB 2 powder has been synthesized via a sol–gel‐based route using phenolic resin, hafnium chloride, and boric acid as the source of carbon, hafnium, and boron respectively, though a small number of comparative experiments involved amorphous boron as the boron source. The effects of calcination dwell time and Hf:C and Hf:B molar ratio on the purity and morphology of the final powder have been studied and the mechanism of anisotropic growth of HfB 2 has been investigated. It is hypothesized that imperfect oriented attachment of finer HfB 2 particles results in screw dislocations in the coarser particles. The screw dislocation facilitates dislocation‐driven growth of particles into anisotropic HfB 2 rods.