Stability of layered Li-Mg-B compounds from first-principles

Numerous metal borides with honeycomb boron networks have been considered in the past two decades in the search for MgB₂-type superconductors. One of the most promising candidates, a layered LiB compound with desired structural and electronic features, has been recently synthesized in diamond anvil cells and predicted to have a critical temperature above 32 K under ambient pressure. Based on our present re-examination of the LiB thermodynamic stability at different (T,P) conditions, we propose that the desired phase could be obtained at lower pressures starting with a delithiated LiB_y compound. We also assess the feasibility of making related Li-Mg-B materials and demonstrate that layered compounds with targeted layered morphologies are metastable under typical synthesis conditions.