Low-Temperature Thermoelectric Properties of β -Ag 2 Se Synthesized by Hydrothermal Reaction

β -Ag 2 Se is a narrow-bandgap semiconductor with a high electrical conductivity, reasonably large Seebeck coefficient, and low thermal conductivity. It is regarded as a potential candidate for thermoelectric applications. In this work, we prepared powders of β -Ag 2 Se by hydrothermal reaction at 180°C. The spark plasma sintering technique was employed to form compact samples. The thermoelectric properties were measured in a temperature range between 20 K and 350 K. A maximum figure of merit of over 0.6 was found around room temperature. Theoretical calculations were carried out to estimate the Seebeck coefficient of β -Ag 2 Se, reproducing the experimental trend qualitatively.