Predicted Electronic and Thermodynamic Properties of a Newly Discovered Zn8Sb7 Phase

A new binary compound, Zn8Sb7, has recently been prepared in nanoparticulate form via solution synthesis. No such phase is known in the bulk phase diagram; instead, one would expect phase separation to the good thermoelectric semiconductors ZnSb and Zn4Sb3. Here, density functional calculations are employed to determine the free energies of formation, including effects from vibrations and configurational disorder, of the relevant phases, yielding insight into the phase stability of Zn8Sb7. Band structure calculations predict Zn8Sb7, much like ZnSb and Zn4Sb3, to be an intermetallic semiconductor with similar thermoelectric properties. If sufficient entropy or surface energy exists to stabilize the bulk material, it would be stable in a limited temperature window at high temperature.