Electronic and Lattice Properties of MgB₂ and Related Phases under Various Compression Conditions

Abstract

We calculated the electronic and lattice properties of MgB₂ (WB₂-type structure), MgB (WC-type structure) and Mg₂B₂ (Wurtzite-type structure) under hydrostatic and anisotropic (c-axis and a,b-axis) compressions. The lattice properties were optimized automatically by the first-principles molecular dynamics (FPMD) method. The most stable structure is MgB₂(AlB₂) over a wide range of compression. There is no lattice anomaly for any phase under various compression conditions. The Mg₂B₂(Wurtzite) phase transforms to a hexagonal-BN (h-BN) type structure (P6₃/mmc) under c-axis compression.