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

A graphite-like material boron carbide (BC) was synthesized under various heat treatment conditions and extensively characterized. First, we synthesized the BC precursor phase by a single-step reaction using a mixed solution of BBr and CH. 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. The high-temperature annealing for the precursor phase yields the highest Pauli paramagnetic susceptibility χ, 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 precursor phase. The crystal structure can be indexed by the AlB structure, indicating that Ti atoms are intercalated between the BC layers. The χ value of TiBC is obtained to be 1 order of magnitude smaller than that of BC, suggesting the compensation of hole carriers by electron doping through Ti intercalation into the BC system.