It was noted that magnesium silicide with its calcium fluorite structure had hardly

been investigated. However, metastable phases of Mg2Si played an important role

in the hardening of 6xxx (AlMgSi-) alloys, and this made it worthwhile to

investigate the formation energy of vacancies in Mg2Si. Here, the formation energy

of vacancies on various sub-lattices was calculated by using an ab initio method.

While the values for the silicon (1.04eV) and magnesium vacancy (1.74eV) were

within the expected range, the formation energy of the di-vacancy and the

stoichiometic tri-vacancy were only 0.68 and 0.78eV, respectively. This was

smaller than the value for either monovacancy.

Vacancies in Magnesium Silicide - Stoichiometric Vacancies Preferred?

T.E.M.Staab: Physica Status Solidi B, 2009, 246[7], 1587-9