Structural Characterization of Graphite Analogue BC x Synthesized Under Various Conditions and Its Application to Ti Intercalation.

A graphite-like material boron carbide (BC x ) was synthesized under various heat treatment conditions and extensively characterized. First, we synthesized the BC x precursor phase by a single-step reaction using a mixed solution of BBr 3 and C 6 H 6 . We confirmed that the precursor phase had a graphite-like structure with B-C chemical bonds, but its crystallinity was poor. To improve their crystallinity, we annealed the precursor sample at high temperature using a high-frequency furnace and determined the annealing condition. We also investigated the magnetic properties of BC x . The high-temperature annealing for the precursor phase yields the highest Pauli paramagnetic susceptibility χ Pauli , indicating the highest density of states at the Fermi level. Accordingly, the high-temperature treatment for the precursor phase is significant to improve its crystallinity and physical properties. In addition, we synthesized a Ti-intercalated material TiBC by using the same procedure as that for making the BC x precursor phase. The crystal structure can be indexed by the AlB 2 structure, indicating that Ti atoms are intercalated between the BC layers. The χ Pauli value of TiBC is obtained to be 1 order of magnitude smaller than that of BC x , suggesting the compensation of hole carriers by electron doping through Ti intercalation into the BC x system.