Enhanced thermoelectric properties of p-type Ag2Te by Cu substitution†
Abstract
Enhanced thermoelectric properties of p-type Ag2Te have been achieved through partial substitution of Ag by Cu. The (Ag0.985−xCux)2Te alloy becomes a β-Ag2Te single-phase solid solution above the structural transition temperature, which is a superionic conductor with highly mobile ions and low lattice thermal conductivity. The substitution of Cu for Ag increases the band gap and hole concentration of the solid solution, leading to not only a suppressed bipolar effect but also greatly improved electrical transport properties. Meanwhile, a periodically modulated layered nanostructure is observed in (Ag0.985−xCux)2Te alloys, which may be attributed to the Cu substitution. As a result, the electrical conductivity increases with the Cu content, and the Seebeck coefficient at high temperature is substantially improved. Both the carrier and lattice thermal conductivities are decreased because of the suppressed bipolar effect and enhanced phonon scattering, respectively. The modified electrical and thermal transport properties enable a maximum ZT value of 1.39 for the sample with x = 0.3, indicating the great potential of superionic conductors as novel thermoelectric materials.
- This article is part of the themed collection: 2015 Journal of Materials Chemistry A Hot Papers