The synthesis and characterization of B6O, B4C and ZrB2 at a pressure of 6 GPa

We obtained a series of B 6 O, B 4 C, ZrB 2 crystals at a pressure of 6 GPa and temperature of 1673–1973 K. These crystals were characterized by XRD and SEM. At a pressure of 6 GPa, the minimum synthesis temperature for B 6 O is 1673 K. The grain size of B 6 O in all the samples remained consistent at around 30–50 nm, with a uniform distribution in each sample. The bonding force between B 6 O grains is weak, and the B 6 O grain size remains relatively stable, showing minimal change with increasing temperature and time. In the sample synthesized at 1973 K, B 6 O icosahedra (multiply twinned particles, MTPs) with a diameter of 12 μm, B 4 C particles with a diameter of 25 μm, and flaky ZrB 2 were observed. We conducted theoretical calculations on B 6 O and B 4 C using density functional theory (DFT).