The Order Disorder phase transition in Zn$_{4}$Sb$_{3}$

Zn$_{4}$Sb$_{3}$ has been widely investigated not only for its promise as a thermoelectric material, [1] but also for the unique transport properties it exhibits. Zn$_{4}$Sb$_{3}$ undergoes two distinct phase transitions (i) from $\alpha $ to $\beta $-phase at T$_{C} \quad \approx $ 250 K and (ii) from $\beta $ to $\gamma $-phase at T$_{C} \quad \approx $ 765 K. [2] We have performed electronic and thermal transport measurements exploring the structural phase transition at T $\approx $ 250 K from the ordered $\alpha $, to the disordered $\beta $ phase. The well-known $\alpha $ to $\beta $ phase transition manifests itself in anomalies in the resistivity, thermopower and specific heat measurements at T $\approx $ 250 K as well as a change in slope in the thermal conductivity, leading to a reduction in thermal conductivity as Zn$_{4}$Sb$_{3}$ changes phase from the ordered to the disordered state. Moreover, measurements of the elastic properties using resonant ultrasound spectroscopy (RUS) reveal dramatic changes at the order-disorder transition. \newline \newline [1] Snyder \textit{et al}., Nature Materials \textbf{3}, 458-463, (2004) \newline [2] Vuillard, G. \textit{et al.}, C.R. Seances Acad. Sci., Ser. C: Sci. Chim. \textbf{263}, 1018-1021, (1966)