Search for superconductivity in LiBC at high pressure*

Lithium borocarbide, which is a structural and electrical analog to high-T$_c$ superconductor MgB$_2$, remains insulating at ambient conditions due to atomic alternation in the crystal structure. We investigated experimentally and theoretically the properties of this material under pressure, including structural and bonding anisotropy and the possibility of metallization and superconductivity under high pressure. It is found to remain stable up to 60 GPa with no crystal structure change and without a previously reported lattice parameter anomaly. In this crystal structure, metallization is not predicted to occur until at least 345 GPa, at which pressure the electronic bands responsible for superconductivity in MgB$_2 $ remain unoccupied in LiBC, ruling out the possibility of a new MgB$_2$-like high pressure superconductor.