Nanostructure engineering has improved the performance of thermoelectric materials, but the deteriorated stability of the materials at high temperatures shortens the service life of thermoelectric modules. Here, we realized a...

As one kind of superionic conductor, CuAgSe is a promising thermoelectric material due to its extremely low thermal conductivity and high electron mobility. In this study, the electrical and thermal...

The thermoelectric figure of merit (ZT) in LaPtBi shows an overall increase with increasing hydrostatic pressure.

In this study, a series of Cu2+x–y In y Se (−0.3 ≤ x ≤ 0.2 and 0 ≤ y ≤ 0.05) samples were prepared by melting and the spark plasma sintering method. X-ray diffraction measurements indicate that the Cu-deficient samples (x = −0.3 y = 0 and x = −0.2 y = 0) prefer to form the cubic phase (β-Cu2Se). Adding excessive Cu or introducing In atoms into the Cu2Se matrix triggers a phase transition from the β to α phase. Positron lifetime measurements confirm the reduction in Cu vacancy concentration by adding excessive Cu or introducing In atoms into Cu2Se, which causes a dramatic decrease in carrier concentration from 1.59 × 1021 to 5.0 × 1019 cm–3 at room temperature. The samples with In contents of 0.01 and 0.03 show a high power factor of about 1 mW m–1 K–2 at room temperature due to the optimization of the carrier concentration. Meanwhile, the excess Cu content and doping of In atoms also favor the formation of nanopores. These pores have strong interaction with phonons, leading to remarkable reduction in lattice thermal conductivity. Finally, a high ZT value of about 1.44 is achieved at 873 K in the Cu1.99In0.01Se (x = 0 and y = 0.01) sample, which is about twice that of the Cu-deficient sample (Cu1.7Se). Our work provides a viable insight into tuning vacancy defects to improve efficiently the electrical and thermal transport performance for copper-based thermoelectric materials.

In this study, polycrystalline SnSe was synthesized via a rapid, cost-effective, and large-scale synthesis route. The obtained SnSe powders were pressed into pellets via spark plasma sintering (SPS) at different temperatures. Powder X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) were used to characterize the crystal structures and morphology of the SnSe samples. The XRD results indicate that the orientation factors increase monotonously with the increase of sintering temperature. The FESEM images show that sintering temperatures have no obvious influence on the particle size. Positron annihilation measurements indicate that vacancy defects exist in all the sintered SnSe samples, and they recover gradually with increasing sintering temperatures. These vacancy defects are responsible for the lower lattice thermal conductivity in samples sintered at lower temperatures. The electrical conductivity, power factor, thermal conductivity, and figure of merit ZT show nearly the same variation trend, which increases initially with the increasing sintering temperature up to 550 °C then decreases with further increase of the sintering temperature, which is possibly due to slight oxidation of SnSe. A maximum ZT value of ∼0.47 at 430 °C was achieved for the 550 °C sintered sample, which is higher than those reported for undoped polycrystalline SnSe around this temperature. Thus, we provide a simple, energy-saving, and effective method to synthesize polycrystalline SnSe in large quantities, and SPS is an effective method to optimize thermoelectric performance.