Chemical Flexibility of Mg in Pnictide Materials: Structure and Properties Diversity

Magnesium, element
no. 12 on the periodic table, is the second
member of the alkaline-earth metal family. Often, Mg is considered
as an electropositive metal like its heavier congeners, Ca, Sr, and
Ba. In this review, another important aspect of Mg chemistry, namely,
the ability to form covalent bonds to more electronegative elements,
is considered with a focus on pnictides. Magnesium’s flexible
coordination numbers and bond distances are similar to those of main
group elements (Al) or late- and post-transition metals (Mn, Cu, Zn,
Cd). In this work, selected Mg-pnictides are discussed to emphasize
the chemical and structural diversity of Mg which results in a variety
of physical properties. Thermoelectric, Mg-ion battery, and nonlinear
optical applications of select Mg-containing compounds are summarized,
providing examples on the exploitation of Mg chemical bonding flexibility
for the design of novel functional materials.