magnesium telluride (MgTe), a compound of magnesium and tellurium, is a white crystal with a very low melting point and a high thermal conductivity. It is obtained by heating magnesium in tellurium vapour with a current of hydrogen, or by acidulating water with a high concentration of hydrogen telluride, or by dissolving magnesium oxide in tellurium vapour and hydrogen telluride.
MgS and MgSe are the members of group II-VI alkaline earth magnesium chalcogenides and they crystallize in rock-salt (B1) structure [41,42]. Theoretical studies have shown that the stable structural phase for MgTe is wurtzite (B4) and that it transforms to nickel-arsenide (B8) under high pressure.
Using first-principles self-consistent local-density calculations in a large plane-wave basis, the electronic structure and total energy of MgSe and MgTe in their rock-salt, wurtzite, zinc blende, nickel arsenide and iron silicide structures are studied. For MgSe, the transition to the iron silicide structure is observed at 107 GPa, and for MgTe it occurs at up to 160 GPa.
Thermoelectric properties are investigated for MgTe, showing a room temperature thermal conductivity of less than 1.4 Wm-1K-1. This is significantly lower than the room temperature thermal conductivity of the wurtzite and the nickel arsenide structures and can be used for efficient thermoelectric conversion.