ja312562d_si_001.pdf (390.73 kB)
Role of Sodium Doping in Lead Chalcogenide Thermoelectrics
journal contribution
posted on 2013-03-27, 00:00 authored by Jiaqing He, Li-Dong Zhao, Jin-Cheng Zheng, Jeff W. Doak, Haijun Wu, Hui-Qiong Wang, Yeseul Lee, Chris Wolverton, Mercouri G. Kanatzidis, Vinayak
P. DravidThe
solubility of sodium and its effects on phonon scattering in
lead chalcogenide PbQ (Q = Te, Se, S) family of thermoelectric materials
was investigated by means of transmission electron microscopy and
density
functional calculations. Among these three systems, Na has the highest
solubility limit (∼2 mol %) in PbS and the lowest ∼0.5
mol %) in PbTe. First-principles electronic structure calculations
support the observations, indicating that Na defects have the lowest
formation energy in PbS and the highest in PbTe. It was also found
that in addition to providing charge carriers (holes) for PbQ, Na
introduces point defects (solid solution formation) and nanoscale
precipitates; both reduce the lattice thermal conductivity by scattering
heat-carrying phonons. These results explain the recent reports of
high thermoelectric performance in p-type PbQ materials and may lead
to further advances in this class of materials.