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A2: Medium temperature materials

High thermoelectric performances of Ag-doped CdSb with intrinsic glasslike thermal conduction

Shanyu Wang, Jiong Yang, Lihua Wu, Ping Wei, Jihui Yang
Materials Science and Engineering Department, University of Washington, Seattle, WA 98195-2120, USA

In this study, Ag-doped p-type CdSb polycrystals were prepared by a melting-annealing followed by spark plasma sintering technique, and a combination of experimental and theoretical efforts was performed to understand the structure and property relation.  The unexpectedly low lattice thermal conductivity (κL) of ~1.0 W/m-K at 300 K originates from large lattice anharmonicity together with low phonon group velocity and low cut-off frequency of the longitudinal acoustical phonon branch. The features of lattice dynamics can be further traced to the unsaturated and soft bonding between Cd and Sb.  In addition, Ag-doping in CdSb, exerting negligible influence on band structure, effectively adjusts the hole concentration and significantly improves the electrical conductivity and power factor.  The maximum power factor reaches ~20 μW/cm-K2, which is comparable to those of PbTe-based materials.  The improved power factor in conjunction with low κL give rise to a maximum ZT of ~1.3 at 560 K and an average of 1.0 between 300 K and 600 K for 0.5 at.% Ag-doped samples, making Ag-doped CdSb an attractive candidate for low -medium temperature or multistage power generation material.