Preparation and thermoelectric properties of InGaSb/Ag-nanoparticles

Abstract

Silver nanoparticles (Ag-NPs) were added to crystalline In0.5Ga0.5Sb alloy prepared by direct-melting synthesis at 1123 K. XRD, SEM, TEM and HRTEM analysis were used to study the crystal structure and morphology of the synthetized In0.5Ga0.5Sb/Agx samples (x = 0,0 0.05, 0.10, 0.15, 0.20, 0.25 wt%). Perfect crystalline single phase of InSb structure was observed for all samples. Investigations of the electrical conductivity were performed in the temperature range 273 K–473 K by the standard four probe method. A differential method using a laboratory made system was used to measure the Seebeck coefficient, over the temperature range 273 K–473 K. Typical semiconductor behavior of the prepared composites was observed over the whole temperature range. Low electrical conductivities were recorded for all samples with a notable increase with elevating temperature. The highest conductivity value was recorded for the parent In0.5Ga0.5Sb alloy, recorded at 70.85 (Ω m)−1 at 473 K, A maximum absolute value of the Seebeck coefficient |S| was recorded for the most Ag-doped alloy observed at room temperature at 366.6 μVK−1. One of the interesting findings of the current study is that the power factor (PF) of the doped samples is higher than that of the undoped alloys at higher temperatures. The maximum power factor was estimated at 2.3 μWm−1 K−2 for the parent sample at 273 K. Addition of Ag-NPs has improved the thermoelectric power factor due to the corresponding enhancement in the Seebeck coefficient of the studied materials. Such enhancement is attributed to the increment of the grain boundaries and the scattering of the carriers. Low thermal conductivity was revealed for the studied composites.