Zn 3 As 2 . This semiconducting phase (E g = 0.44 eV) adopts a Mn 2 O 3 -type structure (space group Ia 3, no. 206) and is one of several polymorphs of Zn 3 As 2 . Several other polymorphs of Zn 3 As 2 are known, including the room-temperature ↵ phase (I4 1 /acd), the high-temperature ↵ 0 phase (P 4 2 /nbc), another high-temperature phase (F m 3m), and the high-temperature, high-pressure ↵ 00 phase (P 4 2 /nmc). The TE properties of Cd 3 As 2 -Zn 3 As 2 alloys have been studied, but the transport properties of the Ia 3 phase has not been measured. There are three conduction bands that are close in energy and located at the Brillouin zone edges (Figure ), yielding a valley degeneracy N V,CB of 3. There are two valence bands close in energy at the -point, yielding a valley degeneracy N V,V B of 2. Despite a modest R of 2.9, the larger band gap (0.44 eV) facilitates a high TE performance. The lower performance compared to SrSb 2 is primarily due to the smaller .