Structural study of LiB to 70 GPa

The interest in low-Z superconducting analogs to MgB2 has motivated a search for new high-pressure phases in metal boride systems. Phases of LiB have electronic features intermediate between those of MgB2 and intercalated graphites, and are expected to exhibit superconductivity. A previously unknown series of layered metal-sandwich structures that are suggested to form under pressure has been identified by ab initio data-mining techniques. We report on an experimental effort to search for structural changes in LiB related to the predicted novel behavior. We find that LiB, while becoming increasingly disordered, maintains its ambient pressure structure up to at least 70 GPa. At 5 GPa, however, we observe an abrupt change in the evolution of c/a as a function of pressure, which is likely related to pressure-induced filling of Li-B bonding states.