Thermodynamic, Structural and Thermoelectric Properties of AgSbTe2 Thick Films Developed by Melt Spinning

Abstract

Cubic AgSbTe2 compound is a metastable phase within Ag2Te-Sb2Te3 pseudo-binary phase diagram and theoretically rapid cooling molten elements to room temperature may be an effective way to obtain it. In this work, thick films composed of 5–10 nm fine grains were developed by a melt spinning technique. The formation mechanism of the nanostructure and its influences on the thermoelectric properties have been studied and correlated. Differential scanning calorimetry (DSC) analysis shows that the as-prepared films exhibit distinct thermodynamic properties when prepared under different cooling rates and doping element. A small amount of Se doping is effectively capable of inhibiting the emergence of the Ag2Te impurity and optimizing the electrical transport properties. All films have positive large Seebeck coefficient, but rather small positive or negative Hall coefficient, indicating a multicarrier nature of transport consisting of both holes and electrons. A power factor of ~1.3 was achieved at 500 K for Se-doped film for its excellent electrical conductivities. This result confirms that a combination of Se doping and melting spinning technique is an effective way to obtain high phase-pure AgSbTe2 compound and reveal its intrinsic transport properties routinely masked by impurities in sintering or slow-cooling bulk samples.

Keywords

• thermoelectric properties
• AgSbTe2
• thick films
• rapid cooling
• melt spinning
• doping
• microstructure